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Full-Text Articles in Cell Biology

Lattice Arrangement Of Myosin Filaments Correlates With Fiber Type In Rat Skeletal Muscle, Weikang Ma, Kyounghwan Lee, Shixin Yang, Thomas C. Irving, Roger Craig Dec 2019

Lattice Arrangement Of Myosin Filaments Correlates With Fiber Type In Rat Skeletal Muscle, Weikang Ma, Kyounghwan Lee, Shixin Yang, Thomas C. Irving, Roger Craig

Radiology Publications and Presentations

The thick (myosin-containing) filaments of vertebrate skeletal muscle are arranged in a hexagonal lattice, interleaved with an array of thin (actin-containing) filaments with which they interact to produce contraction. X-ray diffraction and EM have shown that there are two types of thick filament lattice. In the simple lattice, all filaments have the same orientation about their long axis, while in the superlattice, nearest neighbors have rotations differing by 0 degrees or 60 degrees . Tetrapods (amphibians, reptiles, birds, and mammals) typically have only a superlattice, while the simple lattice is confined to fish. We have performed x-ray diffraction and electron microscopy ...


Structural Organization Of The C1a-E-C Supercomplex Within The Ciliary Central Apparatus, Gang Fu, Lei Zhao, Erin Dymek, Yuqing Hou, Kangkang Song, Nhan Phan, Zhiguo Shang, Elizabeth F. Smith, George B. Witman, Daniela Nicastro Oct 2019

Structural Organization Of The C1a-E-C Supercomplex Within The Ciliary Central Apparatus, Gang Fu, Lei Zhao, Erin Dymek, Yuqing Hou, Kangkang Song, Nhan Phan, Zhiguo Shang, Elizabeth F. Smith, George B. Witman, Daniela Nicastro

Radiology Publications and Presentations

Nearly all motile cilia contain a central apparatus (CA) composed of two connected singlet microtubules with attached projections that play crucial roles in regulating ciliary motility. Defects in CA assembly usually result in motility-impaired or paralyzed cilia, which in humans causes disease. Despite their importance, the protein composition and functions of the CA projections are largely unknown. Here, we integrated biochemical and genetic approaches with cryo-electron tomography to compare the CA of wild-type Chlamydomonas with CA mutants. We identified a large ( > 2 MD) complex, the C1a-e-c supercomplex, that requires the PF16 protein for assembly and contains the CA components FAP76 ...


Extensive Ribosome And Rf2 Rearrangements During Translation Termination, Egor Svidritskiy, Gabriel Demo, Anna B. Loveland, Chen Xu, Andrei A. Korostelev Sep 2019

Extensive Ribosome And Rf2 Rearrangements During Translation Termination, Egor Svidritskiy, Gabriel Demo, Anna B. Loveland, Chen Xu, Andrei A. Korostelev

Open Access Articles

Protein synthesis ends when a ribosome reaches an mRNA stop codon. Release factors (RFs) decode the stop codon, hydrolyze peptidyl-tRNA to release the nascent protein, and then dissociate to allow ribosome recycling. To visualize termination by RF2, we resolved a cryo-EM ensemble of E. coli 70S*RF2 structures at up to 3.3 A in a single sample. Five structures suggest a highly dynamic termination pathway. Upon peptidyl-tRNA hydrolysis, the CCA end of deacyl-tRNA departs from the peptidyl transferase center. The catalytic GGQ loop of RF2 is rearranged into a long beta-hairpin that plugs the peptide tunnel, biasing a nascent ...


Hyaluronan At The Brain-Environment Interface, Donald M. Thevalingam Sep 2019

Hyaluronan At The Brain-Environment Interface, Donald M. Thevalingam

All Dissertations, Theses, and Capstone Projects

Hyaluronan (HA; Hyaluronic Acid), a primary scaffolding component of the brain extracellular matrix, serves as an integral structural component to the brain extracellular space (ECS). The fossorial African naked mole-rat (Heterocephalus glaber; NM-R), a mammal which lives in a low-oxygen environment and is capable of tolerating hypoxia and hypercapnia, has been shown to synthesize and sustain a unique high-molecular-mass variant of hyaluronan macromolecule (HMM-HA). This body of work highlights HA’s role in mediating the interplay between brain ECM composition, ECS structure, and cell viability.

Here we employ the NM-R as a unique animal model to observe the role of ...


Non-Contact Trapping And Stretching Of Biological Cells Using Dual-Beam Optical Stretcher On Microfluidic Platform, Aotuo Dong, Balaadithya Uppalapati, Shariful Islam, Brandon Gibbs, Ganesan Kamatchi, Sacharia Albin, Makarand Deo Jan 2019

Non-Contact Trapping And Stretching Of Biological Cells Using Dual-Beam Optical Stretcher On Microfluidic Platform, Aotuo Dong, Balaadithya Uppalapati, Shariful Islam, Brandon Gibbs, Ganesan Kamatchi, Sacharia Albin, Makarand Deo

Electrical & Computer Engineering Faculty Publications

Optical stretcher is a tool in which two counter-propagating, slightly diverging, and identical laser beams are used to trap and axially stretch microparticles in the path of light. In this work, we utilized the dual-beam optical stretcher setup to trap and stretch human embryonic kidney (HEK) cells and mammalian breast cancer (MBC) cells. Experiments were performed by exposing the HEK cells to counter-propagating laser beams for 30 seconds at powers ranging from 100 mW to 561 mW. It was observed that the percentage of cell deformation increased from 16.7% at 100 mW to 40.5% at 561 mW optical ...


Data On Spectrum-Based Fluorescence Resonance Energy Transfer Measurement Of E. Coli Multidrug Transporter Acrb, Yuguang Cai, Thomas E. Wilkop, Yinan Wei Dec 2018

Data On Spectrum-Based Fluorescence Resonance Energy Transfer Measurement Of E. Coli Multidrug Transporter Acrb, Yuguang Cai, Thomas E. Wilkop, Yinan Wei

Chemistry Faculty Publications

This paper presented the dataset of correction parameters used in the determination of the energy transfer efficiencies from the spectrum-based fluorescence resonance energy transfer (FRET) measurement in a trimeric membrane protein AcrB. The cyan fluorescent protein (CFP) and yellow fluorescent protein (YPet) were used as the donor and acceptor, respectively. Two AcrB fusion proteins were constructed, AcrB-CFP and AcrB-YPet. The proteins were co-expressed in Escherichia coli cells, and energy transfer efficiency were determined in live cells. To obtain reliable energy transfer data, a complete set of correction parameters need to be first determined to accommodate for factors such as background ...


Combined High-Speed Single Particle Tracking Of Membrane Proteins And Super-Resolution Of Membrane-Associated Structures, Hanieh Mazloom Farsibaf, Keith A. Lidke Nov 2018

Combined High-Speed Single Particle Tracking Of Membrane Proteins And Super-Resolution Of Membrane-Associated Structures, Hanieh Mazloom Farsibaf, Keith A. Lidke

Shared Knowledge Conference

Many experiments have shown that the diffusive motion of lipids and membrane proteins are slower on the cell surface than those in artificial lipid bilayers or blebs. One hypothesis that may partially explain this mystery is the effect of the cytoskeleton structures on the protein dynamics. A model proposed by Kusumi [1] is the Fence-Picket Model which describes the cell membrane as a set of compartment regions, each ~ 10 to 200 nm in size, created by direct or indirect interaction of lipids and proteins with actin filaments just below the membrane. To test this hypothesis, we have assembled a high-speed ...


Characterization Of A Variant Of Tuberous Sclerosis Complex 2 And Its Interaction With Rheb, Sowmya Sivakumar Aug 2018

Characterization Of A Variant Of Tuberous Sclerosis Complex 2 And Its Interaction With Rheb, Sowmya Sivakumar

Theses and Dissertations

Protein-protein interactions are vital in maintaining proper function and homeostasis in cells. Some signaling pathways are regulated by G-proteins that work like switches to activate and deactivate pathways. Mutations in these proteins, their effectors or the interaction between proteins may cause dysregulation of signals that can lead to many diseases.

Rheb, Ras homology enriched in brain, is a Ras family GTPase that is vital in regulation of the mTOR (mammalian target of rapamycin) pathway that signals cell proliferation and growth. Due to the low intrinsic GTPase activity of Rheb, a GTPase activating protein (GAP), Tuberous Sclerosis Complex 2 (TSC2) down ...


Developing Droplet Based 3d Cell Culture Methods To Enable Investigations Of The Chemical Tumor Microenvironment, Jacqueline A. De Lora Jul 2018

Developing Droplet Based 3d Cell Culture Methods To Enable Investigations Of The Chemical Tumor Microenvironment, Jacqueline A. De Lora

Biomedical Sciences ETDs

Adaptation of cancer cells to changes in the biochemical microenvironment in an expanding tumor mass is a crucial aspect of malignant progression, tumor metabolism, and drug efficacy. In vitro, it is challenging to mimic the evolution of biochemical gradients and the cellular heterogeneity that characterizes cancer tissues found in vivo. It is well accepted that more realistic and controllable in vitro 3D model systems are required to improve the overall cancer research paradigm and thus improve on the translation of results, but multidisciplinary approaches are needed for these advances. This work develops such approaches and demonstrates that new droplet-based cell-encapsulation ...


Ras Hyperactivation Versus Overexpression: Lessons From Ras Dynamics In Candida Albicans, Vavilala A. Pratyusha, Guiliana Soraya Victoria, Mohammad Firoz Khan, Dominic T. Haokip, Bhawna Yadav, Nibedita Pal, Subhash Chandra Sethi, Priyanka Jain, Sneh Lata Singh, Sobhan Sen, Sneha Sudha Komath Mar 2018

Ras Hyperactivation Versus Overexpression: Lessons From Ras Dynamics In Candida Albicans, Vavilala A. Pratyusha, Guiliana Soraya Victoria, Mohammad Firoz Khan, Dominic T. Haokip, Bhawna Yadav, Nibedita Pal, Subhash Chandra Sethi, Priyanka Jain, Sneh Lata Singh, Sobhan Sen, Sneha Sudha Komath

Open Access Articles

Ras signaling in response to environmental cues is critical for cellular morphogenesis in eukaryotes. This signaling is tightly regulated and its activation involves multiple players. Sometimes Ras signaling may be hyperactivated. In C. albicans, a human pathogenic fungus, we demonstrate that dynamics of hyperactivated Ras1 (Ras1G13V or Ras1 in Hsp90 deficient strains) can be reliably differentiated from that of normal Ras1 at (near) single molecule level using fluorescence correlation spectroscopy (FCS). Ras1 hyperactivation results in significantly slower dynamics due to actin polymerization. Activating actin polymerization by jasplakinolide can produce hyperactivated Ras1 dynamics. In a sterol-deficient hyperfilamentous GPI mutant of C ...


Inactivation Of Myeloma Cancer Cells By Helium And Argon Plasma Jets: The Effect Comparison And The Key Reactive Species, Zeyu Chen, Qingjie Cui, Chen Chen, Dehui Xu, Dingxin Liu, H. L. Chen, Michael G. Kong Feb 2018

Inactivation Of Myeloma Cancer Cells By Helium And Argon Plasma Jets: The Effect Comparison And The Key Reactive Species, Zeyu Chen, Qingjie Cui, Chen Chen, Dehui Xu, Dingxin Liu, H. L. Chen, Michael G. Kong

Bioelectrics Publications

In plasma cancer therapy, the inactivation of cancer cells under plasma treatment is closely related to the reactive oxygen and nitrogen species (RONS) induced by plasmas. Quantitative study on the plasma-induced RONS that related to cancer cells apoptosis is critical for advancing the research of plasma cancer therapy. In this paper, the effects of several reactive species on the inactivation of LP-1 myeloma cancer cells are comparatively studied with variable working gas composition, surrounding gas composition, and discharge power. The results show that helium plasma jet has a higher cell inactivation efficiency than argon plasma jet under the same discharge ...


Cargo Specific Regulation Of Cytoplasmic Dynein By Effector Proteins, Mara Olenick Jan 2018

Cargo Specific Regulation Of Cytoplasmic Dynein By Effector Proteins, Mara Olenick

Publicly Accessible Penn Dissertations

Axonal transport is vital for the development and survival of neurons. The transport of cargo and organelles from the axon to the cell body is driven almost completely by the molecular motor, cytoplasmic dynein. Yet, it remains unclear how dynein is spatially and temporally regulated given the variety of cargo that must be properly localized to maintain cellular function. Previous work has suggested that adaptor proteins provide a mechanism for cargo-specific regulation of motors. During my thesis work, I have investigated the role of mammalian Hook proteins, Hook1 and Hook3, as potential motor adaptors. Using optogenetic and single molecule assays ...


Coordination Of Different Ligands To Copper(Ii) And Cobalt(Iii) Metal Centers Enhances Zika Virus And Dengue Virus Loads In Both Arthropod Cells And Human Keratinocytes, Shovan Dutta, Michael J. Celestine, Supreet Khanal, Alexis Huddleston, Colin Simms, Jessa Faye Arca, Amlam Mitra, Loree Heller, Piotr Kraj, Michael Ledizet, John F. Anderson, Girish Neelakanta, Alvin A. Holder, Hameeda Sultana Jan 2018

Coordination Of Different Ligands To Copper(Ii) And Cobalt(Iii) Metal Centers Enhances Zika Virus And Dengue Virus Loads In Both Arthropod Cells And Human Keratinocytes, Shovan Dutta, Michael J. Celestine, Supreet Khanal, Alexis Huddleston, Colin Simms, Jessa Faye Arca, Amlam Mitra, Loree Heller, Piotr Kraj, Michael Ledizet, John F. Anderson, Girish Neelakanta, Alvin A. Holder, Hameeda Sultana

Biological Sciences Faculty Publications

Trace elements such as copper and cobalt have been associated with virus-host interactions. However, studies to show the effect of conjugation of copper(II) or cobalt(III) metal centers to thiosemicarbazone ligand(s) derived from either food additives or mosquito repellent such as 2-acetylethiazole or citral, respectively, on Zika virus (ZIKV) or dengue virus (serotype 2; DENV2) infections have not been explored. In this study, we show that four compounds comprising of thiosemicarbazone ligand derived from 2-acetylethiazole viz., (E)-N-ethyl-2-[1-(thiazol-2-yl)ethylidene]hydrazinecarbothioamide (acetylethTSC) (compound 1), a copper(II) complex with acetylethTSC as a ligand (compound 2), a thiosemicarbazone ...


Evaluation Of Extracellular Matrix Composition And Rheology As Determinants Of Growth, Invasion, And Response To Photodynamic Therapy In 3d Cell Culture Models Of Pancreatic Ductal Adenocarcinoma, Gwendolyn M. Cramer Dec 2017

Evaluation Of Extracellular Matrix Composition And Rheology As Determinants Of Growth, Invasion, And Response To Photodynamic Therapy In 3d Cell Culture Models Of Pancreatic Ductal Adenocarcinoma, Gwendolyn M. Cramer

Graduate Doctoral Dissertations

Pancreatic ductal adenocarcinoma (PDAC) is a notoriously lethal disease characterized by prominent stromal involvement, which plays complex roles in regulating tumor growth and therapeutic response. The extracellular matrix (ECM)-rich stroma has been implicated as a barrier to drug penetration, although stromal depletion strategies have had mixed clinical success. It remains less clear how biophysical interactions with the ECM regulate invasive progression and susceptibilities to specific therapies. Here, an integrative approach combining 3D cell culture and quantitative imaging techniques is used to evaluate invasive behavior and motility as determinants of response to classical chemotherapy and photodynamic therapy (PDT), in which ...


Investigating Structural And Functional Defects In Als-Causing Profilin 1 Variants, Sivakumar Boopathy Sep 2017

Investigating Structural And Functional Defects In Als-Causing Profilin 1 Variants, Sivakumar Boopathy

GSBS Dissertations and Theses

Mutations in profilin 1 (PFN1) cause amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease that targets motor neurons. PFN1 is a 15 kDa protein that is best known for its role in actin dynamics. However, little is known about the pathological mechanisms of PFN1 in ALS. In this dissertation, it is demonstrated that certain familial ALS-linked mutations severely destabilize the native conformation of PFN1 in vitro and cause accelerated turnover of the PFN1 protein in neuronal cells. This mutation-induced destabilization can account for the high propensity of ALS-linked variants to aggregate and also provides rationale for their reported functional defects ...


Calibrated Brightfield-Based Imaging For Measuring Intracellular Protein Concentration, Nathan Mudrak, Priyanka S. Rana, Michael A. Model Mar 2017

Calibrated Brightfield-Based Imaging For Measuring Intracellular Protein Concentration, Nathan Mudrak, Priyanka S. Rana, Michael A. Model

Undergraduate Research Symposium

Intracellular protein concentration is an essential cell characteristic which manifests itself through the refractive index. The latter can be measured from two or more mutually defocused brightfield images analyzed using the TIE (transport-of-intensity equation). In practice, however, TIE does not always achieve quantitatively accurate results on biological cells. Therefore, we have developed a calibration procedure that involves successive imaging of cells in solutions containing different amounts of added protein. This allows one to directly relate the output of TIE (T) to intracellular protein concentration C (g/l). The resultant relationship has a simple form: C ≈ 1.0(T/V), where ...


Biophysical Tools To Study Cellular Mechanotransduction, Ismeel Muhamed, Farhan Chowdhury, Venkat Maruthamuthu Feb 2017

Biophysical Tools To Study Cellular Mechanotransduction, Ismeel Muhamed, Farhan Chowdhury, Venkat Maruthamuthu

Mechanical & Aerospace Engineering Faculty Publications

The cell membrane is the interface that volumetrically isolates cellular components from the cell's environment. Proteins embedded within and on the membrane have varied biological functions: reception of external biochemical signals, as membrane channels, amplification and regulation of chemical signals through secondary messenger molecules, controlled exocytosis, endocytosis, phagocytosis, organized recruitment and sequestration of cytosolic complex proteins, cell division processes, organization of the cytoskeleton and more. The membrane's bioelectrical role is enabled by the physiologically controlled release and accumulation of electrochemical potential modulating molecules across the membrane through specialized ion channels (e.g., Na, Ca2+, K channels). The ...


Engineering And Evaluating Fluorescent Tools For Endoplasmic Reticulum Zinc, Kyle Pierce Carter Jan 2017

Engineering And Evaluating Fluorescent Tools For Endoplasmic Reticulum Zinc, Kyle Pierce Carter

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Zinc (Zn2+) is an essential micronutrient for human health. However, excess Zn2+ is toxic and Zn2+ deficiency can be fatal, so the concentration of this ion must be carefully controlled within cells. Highlighting the importance of Zn2+ is the observation that approximately 10 % of the genes in the human genome potentially code for a Zn2+-binding protein. The Palmer lab has developed a suite of genetically-encoded biosensors for Zn2+ that use Förster Resonance Energy Transfer (FRET) to provide a readout of Zn2+ concentration within human cells. Measurements with these sensors have revealed heterogeneous ...


Dissecting Molecular Pathways That Ensure Proper Chromosome Segregation And Cell Division, Anna Ye Jan 2017

Dissecting Molecular Pathways That Ensure Proper Chromosome Segregation And Cell Division, Anna Ye

Doctoral Dissertations

Equal segregation of the genome is a prerequisite for cell survival. During cell division the duplicated DNA is compacted into chromosomes and a multi-protein macrostructure, known as the kinetochore (Kt), is assembled on each copy of compacted DNA. Simultaneously, the mitotic spindle, which is made up of microtubules (MTs), is built to facilitate the equal distribution of the chromosomes between the resulting daughter cells. Kinetochores mediate the interaction between the MTs and the chromosomes, properly positioning them for segregation. To ensure that the DNA is equally divided in every cell division, cells have built a surveillance system to detect any ...


Engineered Cytoskeletal Arrays Reveal Mechanisms Of Membrane Transport And Tubulation, Betsy Buechler Mcintosh Jan 2017

Engineered Cytoskeletal Arrays Reveal Mechanisms Of Membrane Transport And Tubulation, Betsy Buechler Mcintosh

Publicly Accessible Penn Dissertations

Within the cell, cytoskeletal molecular motors transport and remodel membrane-bound cargos along microtubule and actin filament tracks. Typically, there are multiple actin and microtubule motors attached to the same cargo, which must coordinate to navigate a complex cytoskeletal environment and deliver their cargos to specific locations. We used an engineering, in vitro reconstitution, approach to investigate the interplay between a processive, microtubule-based motor, kinesin-1, and a non-processive, actin filament-based motor, Myo1c, in a simplified environment with increasing physiological complexity. First, we examined the interplay between purified motors attached to a membrane-coated bead at individual actin filament/microtubule intersections on the ...


Defining The Role Of Phosphorylation And Dephosphorylation In The Regulation Of Gap Junction Proteins, Hanjun Li Dec 2016

Defining The Role Of Phosphorylation And Dephosphorylation In The Regulation Of Gap Junction Proteins, Hanjun Li

Theses & Dissertations

Gap junctions are intercellular channels that permit the free passage of ions, small metabolites, and signaling molecules between neighboring cells. In the diseased human heart, altered ventricular gap junction organization and connexin expression (i.e., remodeling) are key contributors to rhythm disturbances and contractile dysfunction. Connexin43 (Cx43) is the dominant gap junction protein isoform in the ventricle which is under tight regulation by serine/tyrosine phosphorylation. Phosphorylation and dephosphorylation regulate many aspects of Cx43 function including trafficking, assembly and disassembly, electrical and metabolic coupling at the plaque, as well as to modulate the interaction with other proteins.

Serine phosphorylation has ...


Influence Of Ph And Acidic Side Chain Charges On The Behavior Of Designed Model Peptides In Lipid Bilayer Membranes, Venkatesan Rajagopalan Dec 2016

Influence Of Ph And Acidic Side Chain Charges On The Behavior Of Designed Model Peptides In Lipid Bilayer Membranes, Venkatesan Rajagopalan

Theses and Dissertations

The molecular properties of transmembrane proteins and their interactions with lipids regulate biological function. Of particular interest are interfacial aromatic residues and charged residues in the core helix whose functions range from stabilizing the native structure to regulating ion channels. This dissertation addresses the pH dependence and influence of potentially negatively charged tyrosine, glutamic acid or aspartic acid side chains. We have employed GWALP23 (acetyl-GGALW5LALALALALALALW19LAGA-amide) as favorable host peptide framework. We have substituted W5 with Tyr (Y5GWALP23) and Leu residues with Glu (L12E, L14E or L16E) or Asp (L14D or L16D), and have incorporated specific 2H-labeled alanine residues within the ...


Id4 Acts As A Tumor Suppressor Via P53: Mechanistic Insight, Derrick J. Morton Jr. May 2016

Id4 Acts As A Tumor Suppressor Via P53: Mechanistic Insight, Derrick J. Morton Jr.

Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University

Overexpression of tumor-derived mutant p53 is a common event in tumorigenesis, suggesting an advantageous selective pressure in cancer initiation and progression. Given that p53 is found to be mutated in 50% of all human cancers, restoration of mutant p53 to its wild type biological function has been a widely sought after avenue for cancer therapy. Most research efforts have largely focused on restoration of mutant p53 by artificial means given that p53 has some degree of conformational flexibility allowing for introduction of short peptides and artificial compounds. Recently, theoretical modeling and studies focused on restoration of mutant p53 by physiological ...


Mechanism Of Calcium-Dependent Chloride Channel Activation By The Secreted Regulator Clca1, Zeynep Yurtsever May 2016

Mechanism Of Calcium-Dependent Chloride Channel Activation By The Secreted Regulator Clca1, Zeynep Yurtsever

Arts & Sciences Electronic Theses and Dissertations

The calcium-activated chloride channel regulator (CLCA) proteins are key signaling molecules, which are implicated in various diseases through their tissue-specific expression. Human CLCA1 protein, overexpressed in airway epithelia under pathophysiological conditions, is centrally involved in the manifestation of IL-13-driven mucus cell metaplasia (MCM), a hallmark feature of asthma and chronic obstructive pulmonary disease (COPD), for which there are currently no available therapeutics. Elucidating the poorly understood molecular basis of CLCA1 function is thus required to design specific inhibitors of CLCA1 activity to treat MCM in asthma and COPD.

Originally misannotated as ion channels, CLCA proteins are secreted soluble proteins that ...


Biophysical Studies Of Cell Division Protein Localization Mechanisms In Escherichia Coli, Matthew Wayne Bailey May 2016

Biophysical Studies Of Cell Division Protein Localization Mechanisms In Escherichia Coli, Matthew Wayne Bailey

Doctoral Dissertations

How nanometer-scale proteins position accurately within micron-scale bacteria has intrigued both biologists and physicists alike. A critical process requiring precise protein localization is cell division. In most bacteria, cell division starts with the self-assembly of the FtsZ proteins into filaments that form a ring-like structure encircling the cell at its middle, the Z-ring. The Z-ring is a scaffold for additional proteins that synthesize the lateral cell wall which separates the two daughter cells. If division planes are misplaced relative to bacterial chromosomes, also called nucleoids, daughter cells with incomplete genetic material can be produced. In Escherichia coli, research carried out ...


Phosphorylation And Calcium Antagonistically Tune Myosin-Binding Protein C'S Structure And Function, Michael J. Previs, Ji Young Mun, Arthur J. Michalek, Samantha Beck Previs, James Gulick, Jeffrey Robbins, David M. Warshaw, Roger Craig Mar 2016

Phosphorylation And Calcium Antagonistically Tune Myosin-Binding Protein C'S Structure And Function, Michael J. Previs, Ji Young Mun, Arthur J. Michalek, Samantha Beck Previs, James Gulick, Jeffrey Robbins, David M. Warshaw, Roger Craig

Cell and Developmental Biology Publications

During each heartbeat, cardiac contractility results from calcium-activated sliding of actin thin filaments toward the centers of myosin thick filaments to shorten cellular length. Cardiac myosin-binding protein C (cMyBP-C) is a component of the thick filament that appears to tune these mechanochemical interactions by its N-terminal domains transiently interacting with actin and/or the myosin S2 domain, sensitizing thin filaments to calcium and governing maximal sliding velocity. Both functional mechanisms are potentially further tunable by phosphorylation of an intrinsically disordered, extensible region of cMyBP-C's N terminus, the M-domain. Using atomic force spectroscopy, electron microscopy, and mutant protein expression, we ...


Spatial And Temporal Dynamics Of Receptor For Advanced Glycation Endproducts, Integrins, And Actin Cytoskeleton As Probed With Fluorescence-Based Imaging Techniques, Aleem Syed Jan 2016

Spatial And Temporal Dynamics Of Receptor For Advanced Glycation Endproducts, Integrins, And Actin Cytoskeleton As Probed With Fluorescence-Based Imaging Techniques, Aleem Syed

Graduate Theses and Dissertations

Systematic spatial and temporal fluctuations are a fundamental part of any biological process. For example, lateral diffusion of membrane proteins is one of the key mechanisms in their cellular function. Lateral diffusion governs how membrane proteins interact with intracellular, transmembrane, and extracellular components to achieve their function. Herein, fluorescence-based techniques are used to elucidate the dynamics of receptor for advanced glycation end-products (RAGE) and integrin membrane proteins.

RAGE is a transmembrane protein that is being used as a biomarker for various diseases. RAGE dependent signaling in numerous pathological conditions is well studied. However, RAGE lateral diffusion in the cell membrane ...


Molecular And Cellular Approaches Toward Understanding Dynein-Driven Motility, Swathi Ayloo Jan 2016

Molecular And Cellular Approaches Toward Understanding Dynein-Driven Motility, Swathi Ayloo

Publicly Accessible Penn Dissertations

Active transport is integral to organelle localization and their distribution within the cell. Kinesins, myosins and dynein are the molecular motors that drive this long range transport on the actin and microtubule cytoskeleton. Although several families of kinesins and myosins have evolved, there is only one form of cytoplasmic dynein driving active retrograde transport in cells. While dynactin is an essential co-factor for most cellular functions of dynein, the mechanistic basis for this evolutionarily well conserved interaction remains unclear. Here, I use single molecule approaches with purified dynein to reconstitute processes in vitro, and implement an optogenetic tool in neurons ...


Response Of Bacterial Cells To Fluctuating Environment, Sudip Nepal Dec 2015

Response Of Bacterial Cells To Fluctuating Environment, Sudip Nepal

Theses and Dissertations

We have studied morphological and genomic variations occurring in a mesophilic bacterium Escherichia coli (E. coli) in a wide range of continuous and fluctuating hydrostatic pressures. For all the studies here the temperature is maintained at 37◦C, the optimal growth tem- perature of E. coli at atmospheric pressure. Cell division is inhibited at high hydrostatic pressures resulting in an increase of cell length. The increase of cell-length depends on the extent and duration of the stress applied on bacterial cells. We have studied the effect of high pressure stress in three different conditions – (i) Wild-type cells (almost no genetic ...


An Invertebrate Smooth Muscle With Striated Muscle Myosin Filaments, Guidenn Sulbaran, Lorenzo Alamo, Antonio Pinto, Gustavo Marquez, Franklin Mendez, Raul Padron, Roger Craig Oct 2015

An Invertebrate Smooth Muscle With Striated Muscle Myosin Filaments, Guidenn Sulbaran, Lorenzo Alamo, Antonio Pinto, Gustavo Marquez, Franklin Mendez, Raul Padron, Roger Craig

Cell and Developmental Biology Publications

Muscle tissues are classically divided into two major types, depending on the presence or absence of striations. In striated muscles, the actin filaments are anchored at Z-lines and the myosin and actin filaments are in register, whereas in smooth muscles, the actin filaments are attached to dense bodies and the myosin and actin filaments are out of register. The structure of the filaments in smooth muscles is also different from that in striated muscles. Here we have studied the structure of myosin filaments from the smooth muscles of the human parasite Schistosoma mansoni. We find, surprisingly, that they are indistinguishable ...