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Articles 1 - 18 of 18

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Principles For Enhancing Virus Capsid Capacity And Stability From A Thermophilic Virus Capsid Structure, Nicholas P. Stone, Gabriel Demo, Emily Agnello, Brian A. Kelch Jan 2019

Principles For Enhancing Virus Capsid Capacity And Stability From A Thermophilic Virus Capsid Structure, Nicholas P. Stone, Gabriel Demo, Emily Agnello, Brian A. Kelch

University of Massachusetts Medical School Faculty Publications

The capsids of double-stranded DNA viruses protect the viral genome from the harsh extracellular environment, while maintaining stability against the high internal pressure of packaged DNA. To elucidate how capsids maintain stability in an extreme environment, we used cryoelectron microscopy to determine the capsid structure of the thermostable phage P74-26. We find the P74-26 capsid exhibits an overall architecture that is very similar to those of other tailed bacteriophages, allowing us to directly compare structures to derive the structural basis for enhanced stability. Our structure reveals lasso-like interactions that appear to function like catch bonds. This architecture allows the capsid ...


Investigation Of Media Effects On Sinorhizobium Meliloti Glucose Minus, Roxana Apostol Jan 2017

Investigation Of Media Effects On Sinorhizobium Meliloti Glucose Minus, Roxana Apostol

Undergraduate Honors Theses

Although nitrogen fertilizers have certain benefits, the over application of such compounds often results in damages to the ecosystem. In this project, we focus our study on Sinorhizobiom meliloti, a species that lives in symbiosis with alfalfa plants, and through its nitrogen fixation capabilities, restores nitrogen levels in the soil. In our study we aim to gain a better understanding of the carbon metabolism in S. meliloti, mainly by looking at growth patterns in the presence of different carbon sources. Our research picked up on Erik Arvey’s discoveries which pointed out that sucrose inhibits growth of certain glucose minus ...


A Cytoplasmic Peptidoglycan Amidase Homologue Controls Mycobacterial Cell Wall Synthesis, Cara C. Boutte, Christina E. Baer, Kadamba Papavinasasundaram, Weiru Liu, Michael R. Chase, Xavier Meniche, Sarah M. Fortune, Christopher M. Sassetti, Thomas R. Ioerger, Eric J. Rubin Jun 2016

A Cytoplasmic Peptidoglycan Amidase Homologue Controls Mycobacterial Cell Wall Synthesis, Cara C. Boutte, Christina E. Baer, Kadamba Papavinasasundaram, Weiru Liu, Michael R. Chase, Xavier Meniche, Sarah M. Fortune, Christopher M. Sassetti, Thomas R. Ioerger, Eric J. Rubin

Open Access Articles

Regulation of cell wall assembly is essential for bacterial survival and contributes to pathogenesis and antibiotic tolerance in Mycobacterium tuberculosis (Mtb). However, little is known about how the cell wall is regulated in stress. We found that CwlM, a protein homologous to peptidoglycan amidases, coordinates peptidoglycan synthesis with nutrient availability. Surprisingly, CwlM is sequestered from peptidoglycan (PG) by localization in the cytoplasm, and its enzymatic function is not essential. Rather, CwlM is phosphorylated and associates with MurA, the first enzyme in PG precursor synthesis. Phosphorylated CwlM activates MurA ~30 fold. CwlM is dephosphorylated in starvation, resulting in lower MurA activity ...


Phi X 174, David J. Hall Jan 2013

Phi X 174, David J. Hall

Infectious Pathogens

Phi X 174 database number # 1CD3. Phi X 174 is a virus that infects bacteria and was the first DNA-based genome to be sequenced in 1977. This bacteriophage has a [+] circular single-stranded DNA genome. The assembly of the capsid has been successfully done in vitro and is the focus of many studies on self-assembly, drug delivery and nanotechnology.


Human Papilloma Virus 16, David J. Hall Jan 2013

Human Papilloma Virus 16, David J. Hall

Infectious Pathogens

Human Papilloma virus 16, database# 1DZL Infection by most papillomaviruses is either asymptomatic or causes small benign tumors, known as papillomas or warts (e.g. human papillomavirus HPV6 or HPV11). Papillomas caused by some types, however, such as human papillomaviruses 16 and 18, carry a risk of becoming cancerous. Human papilloma virus is a non-enveloped, double stranded, circular DNA virus.


Dengue Virus, David J. Hall Jan 2013

Dengue Virus, David J. Hall

Infectious Pathogens

Dengue virus, database # 1THD Dengue fever, is an infectious tropical disease caused by the dengue virus and transmitted by mosquito. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles. In a small proportion of cases the disease develops into the life-threatening dengue hemorrhagic fever. Dengue is a positive strand RNA virus that is part of the flavivirus family. Dengue is an enveloped virus meaning it has a nucleocapsid protecting the RNA and the nucleocapsid is surrounded by lipids (hence the name enveloped).


Hepatitis B, David J. Hall Jan 2013

Hepatitis B, David J. Hall

Infectious Pathogens

Hepatitis B, database # 2g33. Hepatitis B is an infectious inflammatory illness of the liver caused by the hepatitis B virus (HBV). Hepatitis B virus (HBV) is a member of the Hepadnavirus family.The virus particle, (virion) consists of an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. These virions are 42 nM in diameter. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity.


Biotechnological Improvements Of Bio-Based Fuels And Lubricants: Characterization Of Genes For Branched Chain Fatty Acids And Mono-Acyl Esters, Yuqin Jin Jan 2007

Biotechnological Improvements Of Bio-Based Fuels And Lubricants: Characterization Of Genes For Branched Chain Fatty Acids And Mono-Acyl Esters, Yuqin Jin

Retrospective Theses and Dissertations

The goals of the research in this dissertation are to generate the fundamental technologies that can be used to improve the production and quality of vegetable-oil based biodiesel and biolubricants. Specifically, we sought to test the hypothesis that branched chain fatty acids (BCFAs) can substitute for unsaturated fatty acids in maintaining fluidityin an organism. Toward this goal, we examined the utility of two Bacillus keto-acyl synthase III (KASIII) coding genes (yhfB and yjaX) in producing BCFAs. In conducting this research it was necessary to examine if the E. coli KASIII gene (fabH) was essential for initiating fatty acid biosynthesis and ...


Methanobactin And The Membrane-Associated Methane Monooxygenase In Methanotrophy: A Tale Of Two Proteins, Dongwon Choi Jan 2007

Methanobactin And The Membrane-Associated Methane Monooxygenase In Methanotrophy: A Tale Of Two Proteins, Dongwon Choi

Retrospective Theses and Dissertations

No abstract provided.


In Vitro Expression And Purification Of Class I Mhc Molecules, Loi Cheng May 2006

In Vitro Expression And Purification Of Class I Mhc Molecules, Loi Cheng

Honors Scholar Theses

The major histocompatibility complex (MHC) is a gene family responsible for many critical functions of the immune system in most vertebrates. The MHC consists of three classes differentiated by their structure and function, and MHC class I encodes antigen binding proteins as well as chaperone and accessory proteins such as tapasin. The purpose of this project is to reconstitute several human MHC class I molecules in their peptide-filled and peptide-deficient forms, and to purify these proteins for biochemical study. The expressed proteins include wild type and mutant variants of the fusion protein human leukocyte antigen HLA-B*0801-fos, and human beta-2-microglobulin ...


X-Ray Crystallographic Studies On Adenylosuccinate Synthetase From Escherichia Coli , Zhenglin Hou Jan 1998

X-Ray Crystallographic Studies On Adenylosuccinate Synthetase From Escherichia Coli , Zhenglin Hou

Retrospective Theses and Dissertations

Adenylosuccinate synthetase catalyzes the first committed step in de novo biosyntheses of AMP from IMP and aspartate, using GTP as the energy source. Metal cations, ligand-induced conformational transitions and metabolic effectors significantly influence the catalytic potential of the synthetase. The Mg2+, Mn2+, or Ca 2+ bind to the same site, coordinating alpha-, beta-, and gamma-phosphoryl groups of GTP. The level of catalysis supported by each cation is linked to its influence on the basicity of Asp13, a residue which abstracts the proton from N1 of IMP. Zn2+, a potent inhibitor of the synthetase, coordinates the beta- and gamma-phosphoryl groups of ...


Investigation Of The Gtp-Binding Consensus Sequences In Escherichia Coli Adenylosuccinate Synthetase And The Enzyme's Reaction Mechanism , Chulhun Kang Jan 1995

Investigation Of The Gtp-Binding Consensus Sequences In Escherichia Coli Adenylosuccinate Synthetase And The Enzyme's Reaction Mechanism , Chulhun Kang

Retrospective Theses and Dissertations

In this dissertation, on the basis of the similarities in sequence and structure between GTP-binding proteins and AMPSase, it was of interest to determine whether or not the GTP-binding consensus sequences have similar functions. It will be shown that the GTP-binding consensus sequences found in AMPSase play similar roles to those of the GTPase superfamily. The kinetic results show that Lys331 interacts with GTP through hydrophobic interactions between its linear side chain and the aromatic ring of the guanine base of GTP. Also, structural characterization of the G15V mutant using circular dichroism (CD) spectrometry, NMR spectroscopy, and spectrofluorometry indicated that ...


A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane Dec 1993

A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane

Electronic Theses and Dissertations

Extraction of the lipids of Legionella pneumophila yields phases unlike those produced from other Gram-negative bacteria. A viscous interface forms between the aqueous (wash) and organic phases. More than half of the hydroxylated fatty acids were found distributed between the aqueous phase and the interfacial material, fractions in which such constituents have not been reported in other Gram-negative species. It was further observed that after the material from the aqueous/interfacial phase was dissolved in methanol or chloroform/methanol (2:1 (V/V)), the addition of acetone would create a white, flocculent precipitate. Analyses showed that the supernatant contained fatty ...


Acceptor Reactions And Mechanism Of Leuconostoc Mesenteroides B-512fm Dextransucrase , Aziz Tanriseven Jan 1993

Acceptor Reactions And Mechanism Of Leuconostoc Mesenteroides B-512fm Dextransucrase , Aziz Tanriseven

Retrospective Theses and Dissertations

Although Hanes-Woolf plot showed that methyl [alpha]-D-glucopyranoside was an apparent competitive inhibitor for dextransucrase, a Michaelis-Menten plot using methyl [alpha]-D-glucopyranoside in the presence of high concentration of sucrose showed that it was not a real competitive inhibitor. We have also found that methyl 6-deoxy-[alpha]-D-glucopyranoside and methyl 6-deoxy-6-fluoro-[alpha]-D-glucopyranoside were weak inhibitors, whereas the corresponding sucrose analogues 6-deoxysucrose and 6-deoxy-6-fluorosucrose are very potent inhibitors for dextransucrase. From these findings, it is concluded that the acceptor, methyl [alpha]-D-glucopyranoside, does not compete with sucrose for the sucrose binding-sites and it binds at a separate acceptor binding-site;A ...


The 5Å Resolution Crystal Structure Of Adenylosuccinate Synthetase From Escherichia Coli , Michael Alan Serra Jan 1990

The 5Å Resolution Crystal Structure Of Adenylosuccinate Synthetase From Escherichia Coli , Michael Alan Serra

Retrospective Theses and Dissertations

The technique of X-ray crystallography has been employed to determine the structure of adenylosuccinate synthetase from Escherichia coli to a resolution of 5A. Three crystalline forms of the enzyme have been obtained. The structure determination of the P21 crystal form was pursued due to its excellent diffraction properties and its rapid and reproducible growth. The P21 form crystallizes as a dimer. Unit cell parameters are as follows: a = 73.31(9)A, b = 72.23(7)A, c = 82.87(9)A, [beta] = 108.59°(6). The unit cell volume is 416,700(1,200)A[superscript]3.;A suitable ...


Role Of Carbon Dioxide In The Synthesis Of Amino Acids By A Photosynthetic Bacterium In The Dark , Daniel Hartz Hug Jan 1956

Role Of Carbon Dioxide In The Synthesis Of Amino Acids By A Photosynthetic Bacterium In The Dark , Daniel Hartz Hug

Retrospective Theses and Dissertations

The photosynthetic bacterium, Rhodospirillium rubrum, requires carbon dioxide for aerobic growth in the dark in a medium containing acetate. Resting cells do not oxidize acetate in the dark in the absence CO 2. Dark oxidation of acetate is stimulated by catalytic amounts of malate;Rhodospirillium rubrum when grown in a medium containing malate in the presence of radioactive carbon dioxide yields the following radioactive amino acids: aspartate, glutamate, arginine, tryptophan, proline, threonine, glycine, leucines, tyrosine, serine, methionine, valine, cystine, and lysine; hydroxyproline is tentatively identified. Aspartate, glutamate, alanine, and arginine account for 45 percent of the activity in the cationic ...


The Fixation Of Atmospheric Nitrogen By Yeast , Leo M. Christensen Jan 1926

The Fixation Of Atmospheric Nitrogen By Yeast , Leo M. Christensen

Retrospective Theses and Dissertations

No abstract provided.


Temperature And The Growth Of Yeast , Frank F. Sherwood Jan 1924

Temperature And The Growth Of Yeast , Frank F. Sherwood

Retrospective Theses and Dissertations

No abstract provided.