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Molecular Microbiology

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https://www.readbyqxmd.com/read/28714556/non-canonical-activation-of-histidine-kinase-kdpd-by-phosphotransferase-protein-ptsn-through-interaction-with-the-transmitter-domain
#1
Markus Mörk-Mörkenstein, Ralf Heermann, Yvonne Göpel, Kirsten Jung, Boris Görke
The two-component system KdpD/KdpE governs K(+) homeostasis by controlling synthesis of the high affinity K(+) transporter KdpFABC. When sensing low environmental K(+) concentrations, the dimeric kinase KdpD autophosphorylates in trans and transfers the phosphoryl-group to the response regulator KdpE, which subsequently activates kdpFABC transcription. In Escherichia coli, KdpD can also be activated by interaction with the non-phosphorylated form of the accessory protein PtsN. PtsN stimulates KdpD kinase activity thereby increasing phospho-KdpE levels...
July 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28714554/type-ix-secretion-the-generation-of-bacterial-cell-surface-coatings-involved-in-virulence-gliding-motility-and-the-degradation-of-complex-biopolymers
#2
Paul D Veith, Michelle D Glew, Dhana G Gorasia, Eric C Reynolds
The Type IX Secretion System (T9SS) is present in over 1000 sequenced species/strains of the Fibrobacteres-Chlorobi-Bacteroidetes superphylum. Proteins secreted by the T9SS have an N-terminal signal peptide for translocation across the inner membrane via the SEC translocon and a C-terminal signal for secretion across the outer membrane via the T9SS. Nineteen protein components of the T9SS have been identified including three, SigP, PorX and PorY that are involved in regulation. The inner membrane proteins PorL and PorM and the outer membrane proteins PorK and PorN interact and a complex comprising PorK and PorN forms a large ring structure of 50 nm in diameter...
July 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28710887/elfamycins-inhibitors-of-elongation-factor-tu
#3
REVIEW
Samantha M Prezioso, Nicole E Brown, Joanna B Goldberg
Elfamycins are a relatively understudied group of antibiotics that target the essential process of translation through impairment of EF-Tu function. For the most part, the utility of these compounds has been as laboratory tools for the study of EF-Tu and the ribosome, as their poor pharmacokinetic profile and solubility has prevented implementation as therapeutic agents. However, due to the slowing of the antibiotic pipeline and the rapid emergence of resistance to approved antibiotics, this group is being reconsidered...
July 15, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28710872/gacs-gaca-activates-pyoluteorin-biosynthesis-through-gac-rsm-rsme-cascade-and-rsma-rsme-driven-feedback-loop-in-pseudomonas-protegens-h78
#4
Zheng Wang, Xianqing Huang, Yujie Liu, Guohuan Yang, Yang Liu, Xuehong Zhang
The Gac/Rsm regulatory pathway in Pseudomonas spp. activates the production of various secondary metabolites, such as antibiotics, siderophores, and exoenzymes. However, the biosynthesis of antifungal compound pyoluteorin (Plt) in Pseudomonas protegens H78 is almost entirely inhibited by double deletion of two csrA/rsmA family genes, namely, rsmA and rsmE. Here, we investigated the complicated regulatory mechanism of RsmA and RsmE in Plt biosynthesis in P. protegens H78. RsmE negatively regulated Plt biosynthesis and pltLABCDEFG expression by directly interacting with the mRNA leaders of pltR and pltAB...
July 15, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28710862/identification-of-elor-spr1851-as-a-regulator-of-cell-elongation-in-streptococcus-pneumoniae
#5
Gro Anita Stamsås, Daniel Straume, Anja Ruud Winther, Morten Kjos, Cyril Alexander Frantzen, Leiv Sigve Håvarstein
In a screen for mutations suppressing the lethal loss of PBP2b in Streptococcus pneumoniae we identified Spr1851 (named EloR), a cytoplasmic protein of unknown function whose inactivation removed the requirement for PBP2b as well as RodA. It follows from this that EloR and the two elongasome proteins must be part of the same functional network. This network also includes StkP, as this serine/threonine kinase phosphorylates EloR on threonine 89 (T89). We found that ΔeloR cells, and cells expressing the phosphoablative form of EloR (EloR(T89A) ), are significantly shorter than wild-type cells...
July 15, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28708335/heterogeneity-in-non-epitope-loop-sequence-and-outer-membrane-protein-complexes-alters-antibody-binding-to-the-major-porin-protein-porb-in-serogroup-b-neisseria-meningitidis
#6
Kathryn A Matthias, Michael Brad Strader, Hesham F Nawar, Yamei S Gao, Joonseong Lee, Dhilon S Patel, Wonpil Im, Margaret C Bash
PorB is a well-characterized outer membrane protein that is common among Neisseria species and is required for survival. A vaccine candidate, PorB induces antibody responses that are directed against six variable surface-exposed loops that differ in sequence depending on serotype. Although N. meningitidis is naturally competent and porB genetic mosaicism provides evidence for strong positive selection, the sequences of PorB serotypes commonly associated with invasive disease are often conserved, calling into question the interaction of specific PorB loop sequences in immune engagement...
July 14, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28692133/new-insights-into-enterocin-crl35-mechanism-of-action-and-immunity-revealed-by-heterologous-expression-in-escherichia-coli
#7
Daniela E Barraza, Natalia S Ríos Colombo, Adriana E Galván, Leonardo Acuña, Carlos J Minahk, Augusto Bellomio, Miriam C Chalón
The role of the class IIa bacteriocin membrane receptor protein remains unclear and two different mechanisms have been proposed: the bacteriocin could interact with the receptor changing it to an open conformation or the receptor might act as an anchor allowing subsequent bacteriocin insertion and membrane disruption. Bacteriocin-producing cells synthesize an immunity protein that forms an inactive bacteriocin-receptor-immunity complex. To better understand the molecular mechanism of enterocin CRL35, the peptide was expressed as the suicidal probe EtpM-enterocin CRL35 in Escherichia coli, a naturally insensitive microorganism since it does not express the receptor...
July 10, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28686341/three-regulators-of-g-protein-signaling-differentially-affect-mating-morphology-and-virulence-in-the-smut-fungus-ustilago-maydis
#8
Marino Moretti, Lei Wang, Pierre Grognet, Daniel Lanver, Hannes Link, Regine Kahmann
Regulators of G protein signaling (RGS) proteins modulate heterotrimeric G protein signaling negatively. To broaden an understanding of the roles of RGS proteins in fungal pathogens, we functionally characterized the three RGS protein-encoding genes (rgs1, rgs2 and rgs3) in the phytopathogenic fungus Ustilago maydis. We found that RGS proteins play distinct roles in the regulation of development and virulence. rgs1 had a minor role in virulence when deleted in a solopathogenic strain. In crosses, rgs1 was dispensable for mating and filamentation, but was required for teliospore production...
July 7, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28677124/myba-a-transcription-factor-involved-in-conidiation-and-conidial-viability-of-the-human-pathogen-aspergillus-fumigatus
#9
Isabel Valsecchi, Özlem Sarikaya Bayram, Joanne Wong Sak Hoi, Laetitia Muszkieta, John Gibbons, Marie-Christine Prevost, Adeline Mallet, Jacomina Krijnse-Locker, Oumaima Ibrahim-Granet, Isabelle Mouyna, Paul Carr, Michael Bromley, VishuKumar Aimanianda, Y Jae-Hyuk Yu, Antonis Rokas, Gerhard Braus, Cosmin Saveanu, Özgür Bayram, Jean Paul Latgé
Aspergillus fumigatus, a ubiquitous human fungal pathogen, produces asexual spores (conidia), which are the main mode of propagation, survival, and infection of this human pathogen. In this study, we present the molecular characterization of a novel regulator of conidiogenesis and conidial survival called MybA because the predicted protein contains a Myb DNA binding motif. Cellular localisation of the MybA::Gfp fusion and immunoprecipitation of the MybA::Gfp or MybA::3xHa protein showed that MybA is localised to the nucleus...
July 5, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28671286/structural-characterization-of-the-nap-the-major-adhesion-complex-of-the-human-pathogen-mycoplasma-genitalium
#10
Margot P Scheffer, Luis Gonzalez-Gonzalez, Anja Seybert, Mercè Ratera, Michael Kunz, José M Valpuesta, Ignacio Fita, Enrique Querol, Jaume Piñol, Jaime Martín-Benito, Achilleas S Frangakis
Mycoplasma genitalium, the causative agent of non-gonococcal urethritis and pelvic inflammatory disease in humans, is a small eubacterium that lacks a peptidoglycan cell wall. On the surface of its plasma membrane is the major surface adhesion complex, known as NAP, that is essential for adhesion and gliding motility of the organism. Here, we have performed cryo-electron tomography of intact cells and detergent permeabilized M. genitalium cell aggregates, providing sub-tomogram averages of free and cell-attached NAPs respectively, revealing a tetrameric complex with two-fold rotational (C2) symmetry...
July 3, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28665048/a-toxic-imbalance-of-hsp70s-in-saccharomyces-cerevisiae-is-caused-by-competition-for-cofactors
#11
Kathryn M Keefer, Heather L True
Molecular chaperones are responsible for managing protein folding from translation through degradation. These crucial machines ensure that protein homeostasis is optimally maintained for cell health. However, "too much of a good thing" can be deadly, and the excess of chaperones can be toxic under certain cellular conditions. For example, overexpression of Ssa1, a yeast Hsp70, is toxic to cells in folding-challenged states such as [PSI+]. We discovered that overexpression of the nucleotide exchange factor Sse1 can partially alleviate this toxicity...
June 30, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28665040/multifunctional-enzymes-from-reduced-genomes-model-proteins-for-simple-primordial-metabolism
#12
Burckhard Seelig
Billions of years of evolution have yielded today's complex metabolic networks driven by efficient and highly specialized enzymes. In contrast, the metabolism of the earliest cellular life forms was likely much simpler with only a few enzymes of comparatively low activity. It has been speculated that these early enzymes had low specificities and in turn were able to perform multiple functions. In this issue of Molecular Microbiology, Ferla et al. describe examples of enzymes that catalyze chemically distinct reactions while using the same active site...
June 30, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28657694/the-aspergillus-nidulans-velvet-interacting-protein-vipa-is-involved-in-light-stimulated-heme-biosynthesis
#13
Julian Röhrig, Zhenzhong Yu, Keon-Sang Chae, Jog-Hwa Kim, Kap-Hoon Han, Reinhard Fischer
Filamentous fungi are able to differentiate morphologically and adapt the metabolism to internal and external cues. One major regulator is the so-called velvet protein, VeA, best studied in Aspergillus nidulans. The protein interacts with several other proteins to regulate light sensing, the balance between asexual and sexual development, penicillin biosynthesis or mycotoxin production. Here, we characterized a novel VeA-interacting protein, VipA. The 334 amino acid long protein comprises a FAR1-like DNA-binding domain, known from plant transcription factors like FHY3 (Far-red elongated hypocotyl 3)...
June 28, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28657681/negative-regulation-of-filamentous-growth-in-candida-albicans-by-dig1p
#14
Hannah Regan, Christine Scaduto, Matthew P Hirakawa, Kearney Gunsalus, Tuana Oliveira Correia-Mesquita, Yuan Sun, Yaolin Chen, Carol A Kumamoto, Richard Bennett, Malcolm Whiteway
Transcriptional regulation involves both positive and negative regulatory elements. The Dig1 negative regulators are part of a fungal-specific module that includes a transcription factor (a Ste12 family member) and a Dig1 family member. In S. cerevisiae the post-genome-duplication Dig1/Dig2 proteins regulate MAP kinase controlled signaling pathways involved in mating and filamentous growth. We have identified the single Dig1 ortholog in the fungal pathogen Candida albicans. Genetic studies and transcriptional profiling experiments show that this single protein is implicated in regulation of MAP kinase-controlled processes involved in mating, filamentous growth and biofilm formation, and also influences cAMP-regulated processes...
June 28, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28657670/mapping-the-recognition-domains-of-pneumococcal-fibronectin-binding-proteins-pava-and-pavb-demonstrates-a-common-pattern-of-molecular-interactions-with-fibronectin-type-iii-repeats
#15
Sajida Kanwal, Inga Jensch, Gottfried J Palm, Mark Brönstrup, Manfred Rohde, Thomas P Kohler, Daniela Somplatzki, Werner Tegge, Howard F Jenkinson, Sven Hammerschmidt
Colonization of mucosal respiratory surfaces is a prerequisite for the human pathobiont Streptococcus pneumoniae (the pneumococcus) to cause severe invasive infections. The arsenal of pneumococcal adhesins interacts with a multitude of extracellular matrix proteins. A paradigm for pneumococci is their interaction with the adhesive glycoprotein fibronectin, which facilitates bacterial adherence to host cells. Here, we deciphered the molecular interaction between fibronectin and pneumococcal fibronectin-binding proteins (FnBPs) PavA and PavB, respectively...
June 28, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28640457/primordial-like-enzymes-from-bacteria-with-reduced-genomes
#16
Matteo P Ferla, Jodi L Brewster, Kelsi R Hall, Gary B Evans, Wayne M Patrick
The first cells probably possessed rudimentary metabolic networks, built using a handful of multifunctional enzymes. The promiscuous activities of modern enzymes are often assumed to be relics of this primordial era; however, by definition these activities are no longer physiological. There are many fewer examples of enzymes using a single active site to catalyze multiple physiologically-relevant reactions. Previously, we characterized the promiscuous alanine racemase (ALR) activity of Escherichia coli cystathionine β-lyase (CBL)...
June 22, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28636257/covalent-attachment-and-pro-pro-endopeptidase-ppep-1-mediated-release-of-clostridium-difficile-cell-surface-proteins-involved-in-adhesion
#17
REVIEW
Jeroen Corver, Valentina Cordo', Hans C van Leeuwen, Oleg I Klychnikov, Paul J Hensbergen
In the past decade, Clostridium difficile has emerged as an important gut pathogen. This anaerobic, Gram-positive bacterium is the main cause of infectious nosocomial diarrhea. Whereas much is known about the mechanism through which the C. difficile toxins cause diarrhea, relatively little is known about the dynamics of adhesion and motility, which is mediated by cell surface proteins. This review will discuss the recent advances in our understanding of the sortase-mediated covalent attachment of cell surface (adhesion) proteins to the peptidoglycan layer of C...
June 21, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28628249/defining-a-temporal-order-of-genetic-requirements-for-development-of-mycobacterial-biofilms
#18
Yong Yang, Joseph Thomas, Yunlong Li, Catherine Vilchèze, Keith M Derbyshire, William R Jacobs, Anil K Ojha
Most mycobacterial species spontaneously form biofilms, inducing unique growth physiologies and reducing drug sensitivity. Biofilm growth progresses through three genetically programmed stages: substratum attachment, intercellular aggregation and architecture maturation. Growth of Mycobacterium smegmatis biofilms requires multiple factors including a chaperonin (GroEL1) and a nucleoid-associated protein (Lsr2), although how their activities are linked remains unclear. Here we show that Lsr2 participates in intercellular aggregation, but substratum attachment of Lsr2 mutants is unaffected, thereby genetically distinguishing these developmental stages...
June 19, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28628237/wing-phosphorylation-is-a-major-functional-determinant-of-the-lrs14-type-biofilm-and-motility-regulator-abfr1-in-sulfolobus-acidocaldarius
#19
Lingling Li, Ankan Banerjee, Lisa Franziska Bischof, Hassan Ramadan Maklad, Lena Hoffmann, Anna-Lena Henche, Fabian Veliz, Wolfgang Bildl, Uwe Schulte, Alvaro Orell, Lars-Oliver Essen, Eveline Peeters, Sonja-Verena Albers
In response to a variety of environmental cues, prokaryotes can switch between a motile and a sessile, biofilm-forming mode of growth. The regulatory mechanisms and signaling pathways underlying this switch are largely unknown in archaea but involve small winged helix-turn-helix DNA-binding proteins of the archaea-specific Lrs14 family. Here, we study the Lrs14 member AbfR1 of Sulfolobus acidocaldarius. Small-angle X-ray scattering data are presented, which are consistent with a model of dimeric AbfR1 in which dimerization occurs via an antiparallel coiled coil as suggested by homology modeling...
June 19, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28621879/bactericidal-peptidoglycan-recognition-protein-induces-oxidative-stress-in-escherichia-coli-through-a-block-in-respiratory-chain-and-increase-in-central-carbon-catabolism
#20
Des R Kashyap, Marcin Kuzma, Dominik A Kowalczyk, Dipika Gupta, Roman Dziarski
Mammalian Peptidoglycan Recognition Proteins (PGRPs) kill both Gram-positive and Gram-negative bacteria through simultaneous induction of oxidative, thiol, and metal stress responses in bacteria. However, metabolic pathways through which PGRPs induce these bactericidal stress responses are unknown. We screened Keio collection of Escherichia coli deletion mutants and revealed that deleting genes for respiratory chain flavoproteins or for tricarboxylic acid (TCA) cycle resulted in increased resistance of E. coli to PGRP killing...
June 16, 2017: Molecular Microbiology
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