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Full-Text Articles in Life Sciences

Weak Interactions Between Salmonella Enterica Flhb And Other Flagellar Export Apparatus Proteins Govern Type Iii Secretion Dynamics, Jonathan L. Mcmurry, Tohru Minamino, Yukio Furukawa, Joshua W. Francis Aug 2015

Weak Interactions Between Salmonella Enterica Flhb And Other Flagellar Export Apparatus Proteins Govern Type Iii Secretion Dynamics, Jonathan L. Mcmurry, Tohru Minamino, Yukio Furukawa, Joshua W. Francis

Faculty and Research Publications

The bacterial flagellum contains its own type III secretion apparatus that coordinates protein export with assembly at the distal end. While many interactions among export apparatus proteins have been reported, few have been examined with respect to the differential affinities and dynamic relationships that must govern the mechanism of export. FlhB, an integral membrane protein, plays critical roles in both export and the substrate specificity switching that occurs upon hook completion. Reported herein is the quantitative characterization of interactions between the cytoplasmic domain of FlhB (FlhBC) and other export apparatus proteins including FliK, FlhAC and FliI. FliK and FlhAC bound …


A Synthetic Lethal Screen Identifies A Role For Lin-44/Wnt In C.Elegans Embryogenesis, Samanth N. Hartin, Martin L. Hudson, Curtis Yingling, Brian D. Ackley May 2015

A Synthetic Lethal Screen Identifies A Role For Lin-44/Wnt In C.Elegans Embryogenesis, Samanth N. Hartin, Martin L. Hudson, Curtis Yingling, Brian D. Ackley

Faculty and Research Publications

Background The C. elegans proteins PTP-3/LAR-RPTP and SDN-1/Syndecan are conserved cell adhesion molecules. Loss-of-function (LOF) mutations in either ptp-3 or sdn-1 result in low penetrance embryonic developmental defects. Work from other systems has shown that syndecans can function as ligands for LAR receptors in vivo. We used double mutant analysis to test whether ptp-3 and sdn-1 function in a linear genetic pathway during C. elegans embryogenesis. Results We found animals with LOF in both sdn-1 and ptp-3 exhibited a highly penetrant synthetic lethality (SynLet), with only a small percentage of animals surviving to adulthood. Analysis of the survivors demonstrated that …


Characterization Of Myxococcus Xanthus Mazf And Implications For A New Point Of Regulation, Tye O. Boynton, Jonathan L. Mcmurry, Lawrence J. Shimkets Mar 2013

Characterization Of Myxococcus Xanthus Mazf And Implications For A New Point Of Regulation, Tye O. Boynton, Jonathan L. Mcmurry, Lawrence J. Shimkets

Faculty and Research Publications

During development, Myxococcus xanthus cells undergo programmed cell death (PCD) whereby 80% of vegetative cells die. Previously, the MazF RNA interferase has been implicated in this role. Recently, it was shown that deletion of the mazF gene does not eliminate PCD in wild-type strain DK1622 as originally seen in DZF1. To clarify the role of MazF, recombinant enzyme was characterized using a highly sensitive assay in the presence and absence of the proposed antitoxin MrpC. In contrast to previous reports that MrpC inhibits MazF activity, the hydrolysis rate was enhanced in a concentration-dependent manner with MrpC or MrpC2, an N-terminally …


Bacteriophage Ecology In A Commercial Cucumber Fermentation, Jean Lu, Ilenys M. Perez-Diaz, Janet S. Hayes, Fred Bredit Jr. Dec 2012

Bacteriophage Ecology In A Commercial Cucumber Fermentation, Jean Lu, Ilenys M. Perez-Diaz, Janet S. Hayes, Fred Bredit Jr.

Faculty and Research Publications

To reduce high-salt waste from cucumber fermentations, low-salt fermentations are under development. These fermentations may require the use of starter cultures to ensure normal fermentations. Because potential phage infection can cause starter culture failure, it is important to understand phage ecology in the fermentations. This study investigated the phage ecology in a commercial cucumber fermentation. Brine samples taken from a fermentation tank over a 90-day period were plated onto deMan-Rogosa-Sharpe agar plates. A total of 576 lactic acid bacterial isolates were randomly selected to serve as potential hosts for phage isolation. Filtered brine served as a phage source. Fifty-seven independent …


Helicobacter Pylori Hydrogenase Accessory Protein Hypa And Urease Accessory Protein Ureg Compete With Each Other For Uree Recognition, Stéphane L. Benoit, Jonathan L. Mcmurry, Stephanie A. Hill, Robert J. Maier Oct 2012

Helicobacter Pylori Hydrogenase Accessory Protein Hypa And Urease Accessory Protein Ureg Compete With Each Other For Uree Recognition, Stéphane L. Benoit, Jonathan L. Mcmurry, Stephanie A. Hill, Robert J. Maier

Faculty and Research Publications

Background: The gastric pathogen Helicobacter pylori relies on nickel-containing urease and hydrogenase enzymes in order to colonize the host. Incorporation of Ni2+ into urease is essential for the function of the enzyme and requires the action of several accessory proteins, including the hydrogenase accessory proteins HypA and HypB and the urease accessory proteins UreE, UreF, UreG and UreH. Methods: Optical biosensing methods (biolayer interferometry and plasmon surface resonance) were used to screen for interactions between HypA, HypB, UreE and UreG. Results: Using both methods, affinity constants were found to be 5nM and 13nM for HypA–UreE and 8μM and 14μM for …


Studies Of Food Thickeners In Nigeria For Contamination By Aflatoxigenic Forms Of Aspergillus And Their Detection By Pcr, G. I. Okwu, Premila Achar, Michael J. Ikenebomeh, S. Y. Sreenivasa Aug 2011

Studies Of Food Thickeners In Nigeria For Contamination By Aflatoxigenic Forms Of Aspergillus And Their Detection By Pcr, G. I. Okwu, Premila Achar, Michael J. Ikenebomeh, S. Y. Sreenivasa

Faculty and Research Publications

This paper reports the contamination of ready-to-use food thickeners, collected from the South-East geo-political zone in Nigeria, by aflatoxigenic form of Aspergillus species. A total of 150 samples from different open markets were observed for fungal contamination by using serial dilution-spread plate method. Although, Aspergillus, Fusarium and Penicillium were the most frequently isolated fungi, Aspergillus species were found to be the most prevalent in all the samples. Furthermore, Aspergillus flavus and Aspergillus parasiticus produced aflatoxin on yeast extract sucrose (YES) media incubated for 10 to 15 days at 27°C in a CO2 incubator. Aspergillus niger showed no sign of …


Quantification Of Aflatoxin B1 In Ready-To-Use Food Thickeners In South-East Geo-Political Zone In Nigeria, G. I. Okwu, Premila N. Achar, Santosh K. Sharma Aug 2010

Quantification Of Aflatoxin B1 In Ready-To-Use Food Thickeners In South-East Geo-Political Zone In Nigeria, G. I. Okwu, Premila N. Achar, Santosh K. Sharma

Faculty and Research Publications

A total of 150 ready to use food thickeners were randomly collected from various markets in both urban and rural settings. Four of the samples tested Achi (Brachystegia eurycoma), Akpalata (Afzelia africana), Ofor (Detarium microcarpum), and Ukpo (Mucuna flagellipes) were contaminated with fungal flora. The most common and prevalent fungi observed on incubated powdered form of food thickeners on media, were the Aspergillus group namely Aspergillus flavus, Aspergillus parasiticus and Aspergillus niger. Pure isolates of A. flavus and A. parasiticus from various food thickeners from open markets in Nigeria were screened for their potential to produce aflatoxin B-1 (AFB(1)) on …


Flagellar Formation In C-Ring-Defective Mutants By Overproduction Of Flii, The Atpase Specific For Flagellar Type Iii Secretion, Manabu Konishi, Masaomi Kanbe, Jonathan L. Mcmurry, Shin-Ichi Aizawa Oct 2009

Flagellar Formation In C-Ring-Defective Mutants By Overproduction Of Flii, The Atpase Specific For Flagellar Type Iii Secretion, Manabu Konishi, Masaomi Kanbe, Jonathan L. Mcmurry, Shin-Ichi Aizawa

Faculty and Research Publications

The flagellar cytoplasmic ring (C ring), which consists of three proteins, FliG, FliM, and FliN, is located on the cytoplasmic side of the flagellum. The C ring is a multifunctional structure necessary for flagellar protein secretion, torque generation, and switching of the rotational direction of the motor. The deletion of any one of the fliG, fliM, and fliN genes results in a Fla - phenotype. Here, we show that the overproduction of the flagellum-specific ATPase FliI overcomes the inability of basal bodies with partial C-ring structures to produce complete flagella. Flagella made upon FliI overproduction were paralyzed, indicating that an …


The Helicobacter Pylori Anti-Sigma Factor Flgm Is Predominantly Cytoplasmic And Cooperates With The Flagellar Basal Body Protein Flha, Melanie Rust, Sophie Borchert, Eike Niehus, Sarah A. Gripp, Afrodita Bajceta, Jonathan L. Mcmurry, Sebastian Suerbaum, Kelly T. Hughes, Christine Josenhans Aug 2009

The Helicobacter Pylori Anti-Sigma Factor Flgm Is Predominantly Cytoplasmic And Cooperates With The Flagellar Basal Body Protein Flha, Melanie Rust, Sophie Borchert, Eike Niehus, Sarah A. Gripp, Afrodita Bajceta, Jonathan L. Mcmurry, Sebastian Suerbaum, Kelly T. Hughes, Christine Josenhans

Faculty and Research Publications

Helicobacter pylori requires flagellar motility and orientation to persist actively in its habitat. A particular feature of flagella in most Helicobacter species including H. pylori is a membraneous flagellar sheath. The anti-sigma factor FlgM of H. pylori is unusual, since it lacks an N-terminal domain present in other FlgM homologs, e.g., FlgM of Salmonella spp., whose regulatory function is intimately coupled to its secretion through the flagellar type III secretion system. The aim of the present study was to characterize the localization and secretion of the short H. pylori FlgM in the presence of a flagellar sheath and to elucidate …