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Journal of Bacteriology

Gail G Hardy, Evelyn Toh, Cécile Berne, Yves V Brun
Attachment is essential for microorganisms to establish interactions with both biotic and abiotic surfaces. Stable attachment of Caulobacter crescentus to surfaces requires an adhesive polysaccharide holdfast, but the exact composition of holdfast is unknown. The holdfast is anchored to the cell envelope by outer membrane proteins HfaA, HfaB and HfaD. Holdfast anchor gene mutations result in holdfast shedding and reduced cell adherence. Translocation of HfaA and HfaD to the cell surface requires HfaB. The Wzx homolog, HfsF, is predicted to be a bacterial polysaccharide flippase...
November 20, 2017: Journal of Bacteriology
Amy E Rohlfing, Kathryn M Ramsey, Simon L Dove
The alarmone ppGpp is a critical regulator of virulence gene expression in Francisella tularensis In this intracellular pathogen ppGpp is thought to work in concert with the putative DNA-binding protein PigR and the SspA protein family members MglA and SspA to control a common set of genes. MglA and SspA form a complex that interacts with RNA polymerase (RNAP) and PigR functions by interacting with the RNAP-associated MglA-SspA complex. Prior work suggested that ppGpp exerts its regulatory effects in F. tularensis indirectly by promoting the accumulation of polyphosphate in the cell, which in turn was required for formation of the MglA-SspA complex...
November 20, 2017: Journal of Bacteriology
Melanie J Barnett, Sharon R Long
Sinorhizobium meliloti is a soil-dwelling α-proteobacterium that engages in a nitrogen-fixing root nodule symbiosis with leguminous plants. Cell surface polysaccharides are important for both adapting to stresses in the soil and development of an effective symbiotic interaction. Among the polysaccharides characterized to date, the acidic exopolysaccharides EPS-I (succinoglycan) and EPS-II (galactoglucan) are particularly important for protection from abiotic stresses, biofilm formation, root colonization, and infection of plant roots...
November 20, 2017: Journal of Bacteriology
Gaurav Sharma, Indu Khatri, Srikrishna Subramanian
The chemosensory system (CSS) is amongst the most complex organizations of proteins functioning cooperatively to regulate bacterial motility and other cellular activities. These systems have been studied extensively in bacteria and usually, they are present as a single system. Eight CSS, the highest number in bacteria, have been reported in Myxococcus xanthus DK1622 which are involved in coordinating diverse functions. Here, we have explored and compared the CSS in all available genomes of order Myxococcales...
November 20, 2017: Journal of Bacteriology
Tracy L Raivio
Proteolysis is carefully regulated to prevent untimely destruction of critical proteins. In this issue of the Journal of Bacteriology, Kim and colleagues identify YjfN as a proteolytic regulator that stimulates the activity of the DegP/HtrA protease of Escherichia coli The suicide destruction and transcriptional regulation of YjfN limit its activity to conditions where there are likely to be many misfolded substrate proteins present.
November 6, 2017: Journal of Bacteriology
G Brett Moreau, Aiping Qin, Barbara J Mann
Zinc is an essential nutrient for bacterial growth. Because host cells can restrict pathogen access to zinc as an antimicrobial defense mechanism, intracellular pathogens such as Francisella must sense their environment and acquire zinc in response. In many bacteria, the conserved transcription factor Zur is a key regulator of zinc acquisition. To identify mechanisms of zinc uptake in Francisella novicida U112, RNA sequencing was performed on wild-type and putative zur mutant bacteria. Only three genes were confirmed by quantitative RT-PCR as directly regulated by Zur and zinc limitation...
November 6, 2017: Journal of Bacteriology
Lauren R Walling, J Scott Butler
Type II toxin-antitoxin (TA) systems play a critical role in the establishment and maintenance of bacterial dormancy. They are composed of a protein toxin and its cognate protein antitoxin. They function to regulate growth during conditions of stress, such as starvation or antibiotic treatment. As cellular proteases degrade the antitoxin, which normally binds and neutralizes the toxin, this frees the toxin to act on its cellular targets and arrest bacterial growth. TA systems are of particular concern in pathogenic organisms such as nontypeable Haemophilus influenzae (NTHi), as dormancy may lead to chronic infections and failure of antibiotic treatment...
November 6, 2017: Journal of Bacteriology
Chong Liu, Chong Wai Liew, Yee Hwa Wong, Siok Thing Tan, Wee Han Poh, Sony M S Manimekalai, Sreekanth Rajan, Lingyi Xin, Zhao-Xun Liang, Gerhard Grüber, Scott A Rice, Julien Lescar
RbdA is a positive Regulator of biofilm dispersal of Pseudomonas aeruginosa Its cytoplasmic region (cRbdA) comprises a N-terminal PAS domain followed by a diguanylate cyclase (GGDEF) and an EAL domain, whose phosphodiesterase activity is allosterically stimulated by GTP binding to the GGDEF domain. We report crystal structures of cRbdA and of two binary complexes: with GTP/Mg(2+) bound to the GGDEF active site and with the EAL domain bound to the c-di-GMP substrate. These structures unveil a 2-fold symmetric dimer, stabilized by a closely packed N-terminal PAS domain and a non-canonical EAL dimer...
November 6, 2017: Journal of Bacteriology
Robert C Shields, Greg O'Brien, Natalie Maricic, Alexandria Kesterson, Megan Grace, Stephen J Hagen, Robert A Burne
A network of genes and at least two peptide signaling molecules tightly control when Streptococcus mutans becomes competent to take up DNA from its environment. Widespread changes in the expression of genes occur when S. mutans is presented with competence signal peptides in vitro, including increased production of the alternative sigma factor, ComX, which activates late competence genes. Still, the way that gene products that are regulated by competence peptides influence DNA uptake and cellular physiology are not well understood...
November 6, 2017: Journal of Bacteriology
Joseph J Johnston, Abhishek Shrivastava, Mark J McBride
Flavobacterium johnsoniae exhibits rapid gliding motility over surfaces. At least twenty genes are involved in this process. Seven of these, gldK, gldL, gldM, gldN, sprA, sprE, and sprT encode proteins of the type IX protein secretion system (T9SS). The T9SS is required for surface localization of the motility adhesins SprB and RemA, and for secretion of the soluble chitinase ChiA. Here we demonstrate that the gliding motility proteins GldA, GldB, GldD, GldF, GldH, GldI and GldJ are also essential for secretion...
November 6, 2017: Journal of Bacteriology
Federica A Falchi, Elisa A Maccagni, Simone Puccio, Clelia Peano, Cristina De Castro, Angelo Palmigiano, Domenico Garozzo, Alessandra M Martorana, Alessandra Polissi, Gianni Dehò, Paola Sperandeo
In Gram-negative bacteria, lipopolysaccharide (LPS) contributes to the robust permeability barrier of the outer membrane (OM), preventing the entry of toxic molecules such as detergents and antibiotics. LPS is transported from the inner membrane (IM) to the OM by the Lpt multiprotein machinery. Defects in LPS transport compromise LPS assembly at the OM and result in increased antibiotic sensitivity. LptA is a key component of the Lpt machine that interacts with the IM protein LptC and chaperons LPS through the periplasm...
November 6, 2017: Journal of Bacteriology
Stephanie Gilbert, LaChae Hood, Stephen Y K Seah
The heteromeric acyl-CoA dehydrogenase, FadE28-FadE29 and the enoyl CoA hydratase ChsH1-ChsH2, encoded by genes within the intracellular growth (igr) operon of Mycobacterium tuberculosis, catalyze the dehydrogenation of the 3-carbon side chain cholesterol metabolite, 3-OPC-CoA, and subsequent hydration of the product 3-oxo-4,17-pregnadiene-20-carboxyl-CoA (3-OPDC-CoA) to form 17-hydroxy-3-oxo-4-pregnene-20-carboxyl-CoA (17-HOPC-CoA). The gene downstream of chsH2, ltp2, was expressed in recombinant Rhodococcus jostii RHA1 in combination with other genes within the igr operon...
November 6, 2017: Journal of Bacteriology
Thomas J Silhavy
The Journal of Bacteriology (JB) is a prestigious periodical that publishes research articles that probe fundamental processes in bacteria, archaea, and their viruses, and the molecular mechanisms by which they interact with each other and with their hosts and their environments.….
October 30, 2017: Journal of Bacteriology
Iain D Hay, Matthew J Belousoff, Rhys A Dunstan, Rebecca S Bamert, Trevor Lithgow
The β-barrel assembly machinery (BAM) complex is the core machinery for the assembly of β-barrel membrane proteins, and inhibition of BAM complex activity is lethal to bacteria. Discovery of integral membrane proteins that are key to pathogenesis yet do not require assistance from the BAM complex raises the question of how these proteins assemble into bacterial outer membranes. Here we address this question through a structural analysis of the type 2 secretion system (T2SS) secretin from enteropathogenic Escherichia coli O127:H6 strain E2348/69...
October 30, 2017: Journal of Bacteriology
George A O'Toole
The genetic disease cystic fibrosis (CF) is associated with chronic airway infections that are a proximal cause of death in many patients with this affliction. Classic microbiology studies focusing on canonical pathogens resulted in the development of a common set of views regarding the nature of the airway infections associated with this disease, and these ideas have influenced everything from the way infections are treated to how clinical trials for new CF-targeted antibiotics are designed and the focus of CF-related research topics...
October 30, 2017: Journal of Bacteriology
Maria Peñil Cobo, Silvia Libro, Nils Marechal, David D'Entremont, David Peñil Cobo, Mehmet Berkmen
Capturing microbial growth at the macroscopic scale is of great importance to further our understanding of microbial life. However, methods for macroscale imaging microbial life at millimeter to centimeter scale are often limited by designs that have poor environmental control, resulting in dehydration of the agar plate within just a few days. Here, we created MOCHA (MicrObial CHAmber), a simple yet effective chamber that permits the user to study microbial growth for extended periods of time, lasting weeks within a stable environment...
October 30, 2017: Journal of Bacteriology
Justin R Randall, William G Hirst, Lyle A Simmons
We tested the activity of four predicated RNase H enzymes including two RNase HI-type enzymes in addition to RNase HII (RnhB) and RNase HIII (RnhC) on several RNA:DNA hybrid substrates with different divalent metal cations. We found that the two RNase HI-type enzymes YpdQ and YpeP failed to show activity on the three substrates tested. RNase HII and RNase HIII cleaved all substrates tested although activity was dependent on the metal made available. We show that B. subtilis RNase HII and RNase HIII are both able to incise 5' to a single rNMP...
October 30, 2017: Journal of Bacteriology
Kou-San Ju, Xiafei Zhang, Marie A Elliot
Streptomyces have an extensive natural product repertoire, including most of the naturally-derived antibiotics. Understanding the control of natural product biosynthesis is central to antibiotic discovery and production optimization. Here, Hou et al., report the identification and characterization of a novel regulator - LmbU - that functions primarily as an activator of lincomycin production in Streptomyces lincolnensis Importantly, members of this new regulator family are associated with natural product biosynthetic clusters throughout the streptomycetes and their actinomycete relatives...
October 30, 2017: Journal of Bacteriology
Justin P Hawkins, Patricia A Ordonez, Ivan J Oresnik
Sinorhizobium meliloti is a Gram-negative α-proteobacteria that can enter a symbiotic relationship with Medicago sativa and M. truncatula Previous work had determined that a mutation in the gene tkt2, a putative transketolase, could prevent medium acidification associated with a mutant strain unable to metabolize galactose. Since the pentose phosphate pathway in S. meliloti is not well studied, strains carrying mutations in either tkt2 and tal, a putative transaldolase, were characterized. Carbon metabolism phenotypes revealed that both mutants are impaired in growth on erythritol and ribose...
October 30, 2017: Journal of Bacteriology
Daniel Vega Mendoza, William Margolin
ZipA is essential for cell division in Escherichia coli, acting early in the process to anchor polymers of FtsZ to the cytoplasmic membrane. Along with FtsA, FtsZ and ZipA form a proto-ring at midcell that recruits additional proteins to eventually build the division septum. Cells carrying the thermosensitive zipA1 allele divide fairly normally at 30°C in rich medium but cease dividing at temperatures above 34°C, forming long filaments. In a search for suppressors of zipA1, we found that deletions of specific genes involved in amino acid biosynthesis could partially cell rescue growth and division at 34°C or 37°C, but not at 42°C...
October 23, 2017: Journal of Bacteriology
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