Life Sciences Commons^™

Physical And Structural Basis For The Strong Interactions Of The -Impy- Central Pairing Motif In The Polyamide F-Impyim, K. Buchmueller, S. Bailey, D. Matthews, Z. Taherbhai, J. Register, Z. Davis, Chrystal Bruce, C. O'Hare, J. Hartley, M. Lee

Chrystal D. Bruce

The polyamide f-ImPyIm has a higher affinity for its cognate DNA than either the parent analogue, distamycin A (10-fold), or the structural isomer, f-PyImIm (250-fold), has for its respective cognate DNA sequence. These findings have led to the formulation of a two-letter polyamide “language” in which the -ImPy- central pairings associate more strongly with Watson−Crick DNA than -PyPy-, -PyIm-, and -ImIm-. Herein, we further characterize f-ImPyIm and f-PyImIm, and we report thermodynamic and structural differences between -ImPy- (f-ImPyIm) and -PyIm- (f-PyImIm) central pairings. DNase I footprinting studies confirmed that f-ImPyIm is a stronger binder than distamycin A and f-PyImIm ...

The Exoribonuclease Xrn4 Is A Component Of The Ethylene Response Pathway In Arabidopsis, Brad Binder, Thomas Potuschak, Amérin Vansiri, Esther Lechner, Richard Vierstra, Pascal Genschik

Brad M. Binder

EXORIBONUCLEASE4 (XRN4), the Arabidopsis thaliana homolog of yeast XRN1, is involved in the degradation of several unstable mRNAs. Although a role for XRN4 in RNA silencing of certain transgenes has been reported, xrn4 mutant plants were found to lack any apparent visible phenotype. Here, we show that XRN4 is allelic to the unidentified components of the ethylene response pathway ETHYLENE-INSENSITIVE5/ACC-INSENSITIVE1 (EIN5/AIN1) and EIN7. xrn4 mutant seedlings are ethylene-insensitive as a consequence of the upregulation of EIN3 BINDING F-BOX PROTEIN1 (EBF1) and EBF2 mRNA levels, which encode related F-box proteins involved in the turnover of EIN3 protein, a crucial ...

Ethylene-Stimulated Nutations Do Not Require Etr1 Receptor Histidine Kinase Activity, Brad Binder

Brad M. Binder

Ethylene influences the growth and development of plants through the action of receptors that have homology to bacterial two-component receptors. In bacteria these receptors function via autophosphorylation of a His residue in the kinase domain followed by phosphotransfer to a conserved Asp residue in a response regulator protein. In Arabidopsis, two of the five receptor isoforms are capable of His kinase activity. However, the role of His kinase activity and phosphotransfer is unclear in ethylene signaling. A previous study showed that ethylene stimulates nutations of the hypocotyl in etiolated Arabidopsis seedlings that are dependent on the ETR1 receptor isoform. The ...

A Genomic Approach To Identify Regulatory Nodes In The Transcriptional Network Of Systemic Acquired Resistance In Plants, Dong Wang, Nita Amornsiripanitch, Xinnian Dong

Dong Wang

Many biological processes are controlled by intricate networks of transcriptional regulators. With the development of microarray technology, transcriptional changes can be examined at the whole-genome level. However, such analysis often lacks information on the hierarchical relationship between components of a given system. Systemic acquired resistance (SAR) is an inducible plant defense response involving a cascade of transcriptional events induced by salicylic acid through the transcription cofactor NPR1. To identify additional regulatory nodes in the SAR network, we performed microarray analysis on Arabidopsis plants expressing the NPR1-GR (glucocorticoid receptor) fusion protein. Since nuclear translocation of NPR1-GR requires dexamethasone, we were able ...

Reconstitution Of Protein Targeting To The Inner Envelope Membrane Of Chloroplasts, Ming Li, Danny Schnell

Danny Schnell

The chloroplast envelope plays critical roles in the synthesis and regulated transport of key metabolites, including intermediates in photosynthesis and lipid metabolism. Despite this importance, the biogenesis of the envelope membranes has not been investigated in detail. To identify the determinants of protein targeting to the inner envelope membrane (IM), we investigated the targeting of the nucleus-encoded integral IM protein, atTic40. We found that pre-atTic40 is imported into chloroplasts and processed to an intermediate size (int-atTic40) before insertion into the IM. Int-atTic40 is soluble and inserts into the IM from the internal stromal compartment. We also show that atTic40 and ...

The Structure Of Escherichia Coli Signal Recognition Particle Revealed By Scanning Transmission Electron Microscopy, Lain L. Mainprize, Daniel R. Beniac, Elena Falkovskaia, Robert M. Cleverley, Lila Gierasch, F. Peter Ottensmeyer, David W. Andrews

Lila Gierasch

Structural studies on various domains of the ribonucleoprotein signal recognition particle (SRP) have not converged on a single complete structure of bacterial SRP consistent with the biochemistry of the particle. We obtained a three-dimensional structure for Escherichia coli SRP by cryoscanning transmission electron microscopy and mapped the internal RNA by electron spectroscopic imaging. Crystallographic data were fit into the SRP reconstruction, and although the resulting model differed from previous models, they could be rationalized by movement through an interdomain linker of Ffh, the protein component of SRP. Fluorescence resonance energy transfer experiments determined interdomain distances that were consistent with our ...

A Comprehensive Structure–Function Analysis Of Arabidopsis Sni1 Defines Essential Regions And Transcriptional Repressor Activity, Rebecca Mosher, Wendy Durrant, Dong Wang, Jungi Song, Xinnian Dong

Dong Wang

The expression of systemic acquired resistance (SAR) in plants involves the upregulation of many Pathogenesis-Related (PR) genes, which work in concert to confer resistance to a broad spectrum of pathogens. Because SAR is a costly process, SAR-associated transcription must be tightly regulated. Arabidopsis thaliana SNI1 (for Suppressor of NPR1, Inducible) is a negative regulator of SAR required to dampen the basal expression of PR genes. Whole genome transcriptional profiling showed that in the sni1 mutant, Nonexpresser of PR genes (NPR1)–dependent benzothiadiazole S-methylester–responsive genes were specifically derepressed. Interestingly, SNI1 also repressed transcription when expressed in yeast, suggesting that it ...

Activation In Neural Networks Controlling Ingestive Behaviors: What Does It Mean, And How Do We Map And Measure It?, Alan G. Watts, Arshad M. Khan, Graciela Sanchez-Watts, Dawna Salter, Christina M. Neuner

Arshad M. Khan, Ph.D.

No abstract provided.

Biochemical Characterization Of The Major Sorghum Grain Peroxidase, Mamoudou H. Dicko, Harry Gruppen, Riet Hilhorst, Alphons G. J. Voragen, Willen W. H. Van Berkel

Pr. Mamoudou H. DICKO, PhD

Mid-Ir Biosensor:  Detection And Fingerprinting Of Pathogens On Gold Island Functionalized Chalcogenide Films, Chenxu Yu, Ashtosh Ganjoo, H. Jain, C. G. Pantano, Joseph Irudayaraj

Chenxu Yu

Antibody (human IgG, anti-E. coli O157:H7, and anti-Salmonella) complexes on the surface of IR-transparent Ge-containing chalcogenide glass films were formed via thiol chemistry on 20-nm-thick gold islands. As a first step, the protocol was validated by monitoring fluorescently tagged targets to validate binding. FT-IR spectroscopy confirmed that the coating of the films with 20-nm gold did not have a significant effect on the propagation and penetration of IR evanescent waves through the film. The films functionalized with anti-E. coli O157:H7 and anti-Salmonella antibodies were used to detect E. coli O157:H7 and S. enteriditis through label-free IR fingerprinting ...

The Importance Of Maltose In Transitory Starch Breakdown, Yan Lu, Thomas Sharkey

Yan Lu

No abstract provided.

Dna Damage Responses In Progeroid Syndromes Arise From Defective Maturation Of Prelamin A, Michael Sinensky, Y. Liu, A. Rusinol, Y. Wang, Y. Zou

Michael Sinensky

The genetic diseases Hutchinson-Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD) arise from accumulation of farnesylated prelamin A because of defects in the lamin A maturation pathway. Both of these diseases exhibit symptoms that can be viewed as accelerated aging. The mechanism by which accumulation of farnesylated prelamin A leads to these accelerated aging phenotypes is not understood. Here we present evidence that in HGPS and RD fibroblasts, DNA damage checkpoints are persistently activated because of the compromise in genomic integrity. Inactivation of checkpoint kinases Ataxia-telangiectasia-mutated (ATM) and ATR (ATM- and Rad3-related) in these patient cells can partially overcome their ...

Farnesylated Lamins, Progeroid Syndromes And Farnesyl Transferase Inhibitors, Michael Sinensky, A. E. Rusinol

Michael Sinensky

Three mammalian nuclear lamin proteins, lamin B1, lamin B2 and the lamin A precursor, prelamin A, undergo canonical farnesylation and processing at CAAX motifs. In the case of prelamin A, there is an additional farnesylation-dependent endoproteolysis, which is defective in two congenital diseases: Hutchinson-Gilford progeria (HGPS) and restrictive dermopathy (RD). These two diseases arise respectively from defects in the prelamin A substrate and the enzyme (ZmpSte24) that processes it. Recent work has shed light on the roles of the lamin proteins and the enzymes involved in their farnesylation-dependent maturation. Other experimental work, including mouse model studies, have examined the possibility ...

A Simple Atomic Force Microscopy Method The Visualization Of Polar And Non-Polar Parts Organic Films, A.A. Yu, P.R. Stoney, J.E. Norvillez, M. Vaughn, E.J. Pascial, Barry Bruce, M. Baldo, F. Stellacci

Barry D. Bruce

Here we present a scanning probe microscopy method that allows for the identification of regions of different polarity (i.e. hydrophilicity) in thin organic films. This technique is based on the analysis of the difference between phase images generated at different applied bias voltages in tapping-mode atomic force microscopy. We show that, without any chemical modification of the microscope tip, it is possible to investigate surface properties of complex macromolecular layers, yielding new insight into the functional properties of the photosynthetic electron transport macromolecular complex, Photosystem I.

Cellular And Organ Level Localization Of Maltose In Maltose-Excess Arabidopsis Mutants, Yan Lu, Jon Steichen, Sean Weise, Thomas Sharkey

Yan Lu

No abstract provided.

The Role Of Cytosolic A-Glucan Phosphorylase In Maltose Metabolism And The Comparison Of Amylomaltose In Arabidopsis And E. Coli, Yan Lu, Jon Steichen, Jian Yao, Thomas Sharkey

Yan Lu

No abstract provided.

Identification Of Important Regions For Ethylene Binding And Signaling In The Transmembrane Domain Of The Etr1 Ethylene Receptor Of Arabidopsis, Brad Binder, Wuyi Wang, Jeff Esch, Shin-Han Shiu, Hasi Agula, Caren Chang, Sara Patterson, Anthony Bleecker

Brad M. Binder

The ethylene binding domain (EBD) of the Arabidopsis thaliana ETR1 receptor is modeled as three membrane-spanning helices. We surveyed ethylene binding activity in different kingdoms and performed a bioinformatic analysis of the EBD. Ethylene binding is confined to land plants, Chara, and a group of cyanobacteria but is largely absent in other organisms, consistent with our finding that EBD-like sequences are overrepresented among plant and cyanobacterial species. We made amino acid substitutions in 37 partially or completely conserved residues of the EBD and assayed their effects on ethylene binding and signaling. Mutations primarily in residues in Helices I and II ...

Interfacial Properties And Structural Conformation Of Thermosonicated Bovice Serum Albumin, D. Guzey, I. Gulseren, Barry Bruce, J. Weiss

Barry D. Bruce

Aqueous Bovine Serum Albumin (BSA) solutions were treated with high-intensity ultrasound (20 W cm⁻²) for 15, 30 and 45 min at temperatures of up to 85 °C. The equilibrium and dynamic surface tension of native and ultrasonicated BSA at the air-solution interface was measured using drop shape analysis. The effect of ultrasound on the secondary structure of BSA was monitored by circular dichroism spectroscopy. Surface pressure of BSA at the air-solvent interface increased as a consequence of sonication treatment at 20 °C. Both the rate of surface pressure increase and the equilibrium surface pressure of sonicated BSA were significantly ...

Soluble Fibrin Inhibits Monocyte Adherence And Cytotoxicity Against Tumor Cells: Implications For Cancer Metastasis, John Biggerstaff, Brandy Weidow, Jacqueline Vidosh, Judith Dexheimer, Shonak Patel, Pretesh Patel

John Biggerstaff

Background Soluble fibrin (sFn) is a marker for disseminated intravascular coagulation and may have prognostic significance, especially in metastasis. However, a role for sFn in the etiology of metastatic cancer growth has not been extensively studied. We have reported that sFn cross-linked platelet binding to tumor cells via the major platelet fibrin receptor αIIbβ3, and tumor cell CD54 (ICAM-1), which is the receptor for two of the leukocyte β2 integrins (αLβ2 and aMβ2). We hypothesized that sFn may also affect leukocyte adherence, recognition, and killing of tumor cells. Furthermore, in a rat experimental metastasis model sFn pre-treatment of tumor cells ...

Ethylene Stimulates Nutations That Are Dependent On The Etr1 Receptor, Brad M. Binder, Ronan C. O'Malley, Wuyi Wang, Tobias C. Zutz, Anthony B. Bleeker

Brad M. Binder

Ethylene influences a number of processes in Arabidopsis (Arabidopsis thaliana) through the action of five receptors. In this study, we used high-resolution, time-lapse imaging to examine the long-term effects of ethylene on growing, etiolated Arabidopsis seedlings. These measurements revealed that ethylene stimulates nutations of the hypocotyls with an average delay in onset of over 6 h. The nutation response was constitutive in ctr1-2 mutants maintained in air, whereas ein2-1 mutants failed to nutate when treated with ethylene. Ethylene-stimulated nutations were also eliminated in etr1-7 loss-of-function mutants. Transformation of the etr1-7 mutant with a wild-type genomic ETR1 transgene rescued the nutation ...

Exchange Coupling And Contribution Of Induced Orbital Angular Momentum Of Low-Spin Fe^3+ Ions To Magnetic Anisotropy In Cyanide-Bridged Fe2m2 Molecular Magnets: Spin-Polarized Density-Functional Calculations, Stephen Holmes, Kyungwha Park

Stephen Holmes