Microbiology Commons^™

Mscs-Like Mechanosensitive Channels In Plants And Microbes, Margaret E. Wilson, Grigory Maksaev, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

The challenge of osmotic stress is something all living organisms must face as a result of environmental dynamics. Over the past three decades, innovative research and cooperation across disciplines have irrefutably established that cells utilize mechanically gated ion channels to release osmolytes and prevent cell lysis during hypoosmotic stress. Early electrophysiological analysis of the inner membrane of Escherichia coli identified the presence of three distinct mechanosensitive activities. The subsequent discoveries of the genes responsible for two of these activities, the mechanosensitive channels of large (MscL) and small (MscS) conductance, led to the identification of two diverse families of mechanosensitive channels. …

Characterization Of Phycoerythrin Physiology In Low-Light Adapted Prochlorococcus Ecotypes, Kathryn H. Roache-Johnson

Electronic Theses and Dissertations

The marine cyanobacteria Prochlorococcus and Synechococcus are the most abundant phototrophs in the oceans. They cohabit the oligotrophic ocean and thus have coevolved together, yet they have distinctly different methods for harvesting light. Synechococcus, like other cyanobacteria, possess phycobilisomes with various combinations of phycobiliproteins to capture wavelengths of light not otherwise available to chlorophyll. Prochlorococcus lack phycobilisomes and use divinyl chlorophyll b (Chl b2) as their primary accessory pigment to divinyl chlorophyll a (Chl a2) to capture light energy. In addition to the divinyl chlorophylls, Prochlorococcus has genes associated with the phycobiliprotein phycoerythrin (PE), the role of which is still …

Function And X-Ray Crystal Structure Of Escherichia Coli Yfde, Elwood A. Mullins, Kelly L. Sullivan, T. Joseph Kappock

T. Joseph Kappock

Many food plants accumulate oxalate, which humans absorb but do not metabolize, leading to the formation of urinary stones. The commensal bacterium Oxalobacter formigenes consumes oxalate by converting it to oxalyl-CoA, which is decarboxylated by oxalyl-CoA decarboxylase (OXC). OXC and the class III CoA-transferase formyl-CoA:oxalate CoA-transferase (FCOCT) are widespread among bacteria, including many that have no apparent ability to degrade or to resist external oxalate. The EvgA acid response regulator activates transcription of the Escherichia coli yfdXWUVE operon encoding YfdW (FCOCT), YfdU (OXC), and YfdE, a class III CoA-transferase that is ~30% identical to YfdW. YfdW and YfdU are necessary …

Cooperative Effects Of Drug-Resistance Mutations In The Flap Region Of Hiv-1 Protease, Jennifer Foulkes-Murzycki, Christina Rosi, Nese Yilmaz, Robert Shafer, Celia Schiffer

Celia A. Schiffer

Understanding the interdependence of multiple mutations in conferring drug resistance is crucial to the development of novel and robust inhibitors. As HIV-1 protease continues to adapt and evade inhibitors while still maintaining the ability to specifically recognize and efficiently cleave its substrates, the problem of drug resistance has become more complicated. Under the selective pressure of therapy, correlated mutations accumulate throughout the enzyme to compromise inhibitor binding, but characterizing their energetic interdependency is not straightforward. A particular drug resistant variant (L10I/G48V/I54V/V82A) displays extreme entropy-enthalpy compensation relative to wild-type enzyme but a similar variant (L10I/G48V/I54A/V82A) does not. Individual mutations of sites …

Physiological Effects Of Nickel Chloride On The Freshwater Cyanobacterium Synechococcus Sp. Iu 625, Brian Nohomovich, Bao T. Nguyen, Michael Quintanilla, Lee H. Lee, Sean R. Murray, Tin-Chun Chu

Tinchun Chu, Ph.D.

Novobiocin As An Allosteric Modulator Of Ste2p, Jeffrey K. Rymer, Melinda Hauser, Jeffrey M. Becker

EURēCA: Exhibition of Undergraduate Research and Creative Achievement

G protein-coupled receptors (GPCRs) are the target of 30-50% of all prescribed drugs for human medicine and are therefore the subject of intense study by the scientific community. It has been recognized recently that compounds called allosteric modulators can regulate GPCR activity by binding a GPCR at sites not occupied by the normal receptor-activating molecule. Such allosteric compounds are desirable drug candidates as they may produce fewer toxic side-effects than standard drugs that target GPCRs. The purpose of this study was to determine the interaction of different allosteric modulators with Ste2p, a model GPCR expressed in the yeast Saccharomyces cerevisiae. …

The Role Of Bacterial Microcompartments In The Fermentation Of D-Arabinose In Clostridium Phytofermentans, Megan A. Strough

Masters Theses 1911 - February 2014

Bacterial microcompartments, or BMCs, are 80-200nm, enzyme-encompassing organelles composed of interlocking proteins that form cyclical hexamers with a small central pore. Clostridium phytofermentans or Cphy, is a Gram-positive, rod shaped, anaerobic soil microbe that has the ability to not only break down multiple polysaccharides simultaneously but also proceeds to ferment them into biofuels. The genome of Cphy contains 3 BMC loci. During growth on fucose and rhamnose, one of these loci is highly expressed and microcompartments can be viewed using TEM. Under these growth conditions, three products, ethanol, propanol and propionate, which could potentially be highly useful in the biofuel …

Sustainable Biofuels Production Through Understanding Fundamental Bacterial Pathways Involved In Biomass Degradation And Sugar Utilization, James Cm Hayes

Masters Theses 1911 - February 2014

Genomic analysis and physiological experiments conducted on the lignocellulosic biomass degrading bacterium C. phytofermentans, indicates that it can degrade and utilize a wide-range of carbohydrates as possible growth substrates. Previous experiments characterized gene expression using custom whole genome oligonucleotide microarrays. The results indicated that C. phytofermentans utilizes ATP-binding cassette (ABC) transporters for carbohydrate uptake and does not use the sole phosphoenolpyruvate-phosphotransferase system (PTS) for any of the tested substrates.Distinct sets of Carbohydrate Active Enzymes (CAZy) genes were also up-regulated on specific substrates indicative of C. phytofermentans ability to selectively degrade lignocellulosic biomass. We also identified a highly expressed cluster of …

Phenotypic And Genotypic Characterization Of Escherichia Coli Isolated From Untreated Surface Waters, Steven L. Daniel, Kai F. Hung, Kristopher J. Janezic, Blake Ferry, Eric W. Hendricks, Brian A. Janiga, Tiffany Johnson, Samantha Murphy, Morgan E. Roberts, Sarah M. Scott, Alexandra N. Theisen

Steven L. Daniel

A common member of the intestinal microbiota in humans and animals is Escherichia coli. Based on the presence of virulence factors, E. coli can be potentially pathogenic. The focus of this study was to isolate E. coli from untreated surface waters (37 sites) in Illinois and Missouri and determine phenotypic and genotypic diversity among isolates. Water samples positive for fecal coliforms based on the Colisure® test were streaked directly onto Eosin Methylene Blue (EMB) agar (37°C) or transferred to EC broth (44.5°C). EC broth cultures producing gas were then streaked onto EMB agar. Forty-five isolates were identified as E. coli …

The Effects Of Uv Light On The Antimicrobial Activities Of Cave Actinomycetes, Devon Rule, Naowarat Cheeptham

International Journal of Speleology

The goal of this study was to determine whether actinomycetes isolated from a volcanic cave in western Canada could produce novel antimicrobial compounds against six multidrugresistant pathogens when exposed to UV light. One hundred and seventy-six actinomycete strains isolated from Helmcken Falls Cave, Wells Gray Provincial Park, BC, were screened against six pathogens using the “plug assay” in UV light and no light conditions. Of the 176 strains tested, 100 or 57% of the cave actinomycete strains had antimicrobial activities against the pathogens in 124 different instances: 35 instances when exposed to UV and no light, 30 when exposed to …

A Bacterial Symbiont Is Converted From An Inedible Producer Of Beneficial Molecules Into Food By A Single Mutation In The Gaca Gene, Pierre Stallforth, Debra A. Brock, Alexandra M. Cantley, Xiangjun Tian, David C. Queller, Joan E. Strassmann, Jon Clardy

Biology Faculty Publications & Presentations

Stable multipartite mutualistic associations require that all partners benefit. We show that a single mutational step is sufficient to turn a symbiotic bacterium from an inedible but host-beneficial secondary metabolite producer into a host food source. The bacteria's host is a "farmer" clone of the social amoeba Dictyostelium discoideum that carries and disperses bacteria during its spore stage. Associated with the farmer are two strains of Pseudomonas fluorescens, only one of which serves as a food source. The other strain produces diffusible small molecules: pyrrolnitrin, a known antifungal agent, and a chromene that potently enhances the farmer's spore production and …