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Molecular Microbiology

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https://www.readbyqxmd.com/read/28925530/the-role-of-a-cytoplasmic-loop-of-mota-in-load-dependent-assembly-and-disassembly-dynamics-of-the-mota-b-stator-complex-in-the-bacterial-flagellar-motor
#1
Seyedeh Noorolhoda Shajari Pourjaberi, Naoya Terahara, Keiichi Namba, Tohru Minamino
The proton-driven flagellar motor of Salmonella enterica can accommodate a dozen MotA/B stators in a load-dependent manner. The C-terminal periplasmic domain of MotB acts as a structural switch to regulate the number of active stators in the motor in response to load change. The cytoplasmic loop termed MotAC is responsible for the interaction with a rotor protein, FliG. Here, to test if MotAC is responsble for stator assembly around the rotor in a load-dependent manner, we analyzed the effect of MotAC mutations, M76V, L78W, Y83C, Y83H, I126F, R131L, A145E and E155K, on motor performance over a wide range of external load...
September 19, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28925527/one-gene-two-proteins-coordinated-production-of-a-copper-chaperone-by-differential-transcript-formation-and-translational-frameshifting-in-escherichia-coli
#2
Steffen Lorenz Drees, Birgit Klinkert, Stefan Helling, Dominik Fabian Beyer, Katrin Marcus, Franz Narberhaus, Mathias Lübben
Programmed ribosomal frameshifting (PRF) is a translational anomaly causing the ribosome to shift into an alternative reading frame. PRFs are common in viral genomes, using a single nucleotide sequence to code for two proteins in overlapping frames. In bacteria and eukaryota, PRFs are less frequent. We report on a PRF in the copper detoxification system of Escherichia coli where a metallochaperone is generated out of the first 69 amino acids and a C-terminal out-of-frame glycine of the gene copA. copA besides codes for the P1B -ATPase CopA, a membrane-integral protein and principal interaction target of the chaperone...
September 19, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28925526/sub1-has-photoreceptor-dependent-and-independent-functions-in-sexual-development-and-secondary-metabolism-in-trichoderma-reesei
#3
Hoda Bazafkan, Sabrina Beier, Eva Stappler, Stefan Böhmdorfer, Josua T Oberlerchner, Michael Sulyok, Monika Schmoll
Light dependent processes are involved in the regulation of growth, development and enzyme production in Trichoderma reesei. The photoreceptors BLR1, BLR2 and ENV1 exert crucial functions in these processes. We analyzed the involvement of the transcription factor SUB1 in sexual development as well as secondary metabolism and its position in the light signaling cascade. SUB1 influences growth and in contrast to its homologue in N. crassa, SUB1 is not essential for fruiting body formation and male fertility in T...
September 19, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28922502/the-three-component-system-esrisr-regulates-a-cell-envelope-stress-response-in-corynebacterium-glutamicum
#4
Britta Kleine, Ava Chattopadhyay, Tino Polen, Daniela Pinto, Thorsten Mascher, Michael Bott, Melanie Brocker, Roland Freudl
When the cell envelope integrity is compromised, bacteria trigger signaling cascades resulting in the production of proteins that counteract these extracytoplasmic stresses. Here, we show that the two-component system EsrSR regulates a cell envelope stress response in the Actinobacterium Corynebacterium glutamicum. The sensor kinase EsrS possesses an amino-terminal phage shock protein C (PspC) domain, a property that sets EsrSR apart from all other two-component systems characterized so far. An integral membrane protein, EsrI, whose gene is divergently transcribed to the esrSR gene locus and which interestingly also possesses a PspC domain, acts as an inhibitor of EsrSR under non-stress conditions...
September 18, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28922497/mutual-independence-of-alkaline-and-calcium-mediated-signalling-in-aspergillus-fumigatus-refutes-the-existence-of-a-conserved-druggable-signalling-nexus
#5
Omar Loss, Margherita Bertuzzi, Yu Yan, Natalie Fedorova, Bethany L McCann, Darius Armstrong-James, Eduardo A Espeso, Nick D Read, William C Nierman, Elaine M Bignell
Functional coupling of calcium- and alkaline responsive signalling occurs in multiple fungi to afford efficient cation homeostasis. Host microenvironments exert alkaline stress and potentially toxic concentrations of Ca(2+) , such that highly conserved regulators of both calcium- (Crz) and pH- (PacC/Rim) responsive signalling are crucial for fungal pathogenicity. Drugs targeting calcineurin are potent antifungal agents but also perturb human immunity thereby negating their use as anti-infectives, abrogation of alkaline signalling has therefore been postulated as an adjunctive antifungal strategy...
September 18, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28906060/novel-coordination-of-lipopolysaccharide-modifications-in-vibrio-cholerae-promotes-camp-resistance
#6
Carmen M Herrera, Jeremy C Henderson, Alexander A Crofts, M Stephen Trent
In the environment and during infection, the human intestinal pathogen Vibrio cholerae must overcome noxious compounds that damage the bacterial outer membrane. The El Tor and classical biotypes of O1 V. cholerae show striking differences in their resistance to membrane disrupting cationic antimicrobial peptides (CAMPs), such as polymyxins. The classical biotype is susceptible to CAMPs, but current pandemic El Tor biotype isolates gain CAMP resistance by altering the net charge of their cell surface through glycine modification of lipid A...
September 14, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28906055/the-role-of-genomic-location-and-flanking-3-utr-in-the-generation-of-functional-levels-of-variant-surface-glycoprotein-in-trypanosoma-brucei
#7
Sophie Ridewood, Cher-Pheng Ooi, Belinda Hall, Anna Trenaman, Nadina Vasileva Wand, Georgios Sioutas, Iris Scherwitzl, Gloria Rudenko
Trypanosoma brucei faces relentless immune attack in the mammalian bloodstream, where it is protected by an essential coat of Variant Surface Glycoprotein (VSG) comprising ∼10% total protein. The active VSG gene is in a Pol I-transcribed telomeric expression site (ES). We investigated factors mediating these extremely high levels of VSG expression by inserting ectopic VSG117 into VSG221 expressing T. brucei. Mutational analysis of the ectopic VSG 3'UTR demonstrated the essentiality of a conserved 16-mer for mRNA stability...
September 14, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28906045/actinorhodin-is-a-redox-active-antibiotic-with-a-complex-mode-of-action-against-gram-positive-cells
#8
Stefanie Mak, Justin R Nodwell
Actinorhodin is a blue-pigmented, redox-active secondary metabolite that is produced by the bacterium Streptomyces coelicolor. Although actinorhodin has been used as a model compound for studying secondary metabolism, its biological activity is not well understood. Indeed, redox-active antibiotics in general have not been widely investigated at the mechanistic level. In this work, we have conducted a comprehensive chemical genetic investigation of actinorhodin's antibacterial effect on target organisms. We find that actinorhodin is a potent, bacteriostatic, pH-responsive antibiotic...
September 14, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28898511/mutations-in-the-major-gas-vesicle-protein-gvpa-and-impacts-on-gas-vesicle-formation-in-haloferax-volcanii
#9
Regine Knitsch, Marie Schneefeld, Kerstin Weitzel, Felicitas Pfeifer
Gas vesicles are proteinaceous, gas-filled nanostructures produced by some bacteria and archaea. The hydrophobic major structural protein GvpA forms the ribbed gas vesicle wall. An in-silico 3D-model of GvpA of the predicted coil-α1-β1-β2-α2-coil structure is available and implies that the two β-chains constitute the hydrophobic interior surface of the gas vesicle wall. To test the importance of individual amino acids in GvpA we performed 85 single substitutions and analysed these variants in Haloferax volcanii ΔA+Amut transformants for their ability to form gas vesicles (Vac(+) phenotype)...
September 12, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28898501/growth-of-pseudomonas-aeruginosa-in-zinc-poor-environments-is-promoted-by-a-nicotianamine-related-metallophore
#10
Maria Chiara Mastropasqua, Melania D'Orazio, Mauro Cerasi, Francesca Pacello, Angelo Gismondi, Antonella Canini, Lorena Canuti, Ada Consalvo, Domenico Ciavardelli, Barbara Chirullo, Paolo Pasquali, Andrea Battistoni
Previous studies have suggested that P. aeruginosa possesses redundant zinc uptake systems. To identify uncharacterized zinc transporters, we analyzed the genome-wide transcriptional responses of P. aeruginosa PA14 to zinc restriction. This approach led to the identification of an operon (zrmABCD) regulated by the zinc uptake regulator Zur, that encodes for a metallophore-mediated zinc import system. This operon includes the genes for an uncharacterized TonB-dependent Outer Membrane Protein (ZrmA) and for a putative nicotianamine synthase (ZrmB)...
September 12, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28898487/structural-and-thermodynamic-characterization-of-metal-binding-in-vps29-from-entamoeba-histolytica-implication-in-retromer-function
#11
Vijay Kumar Srivastava, Rupali Yadav, Watanabe Natsuki, Priya Tomar, Madhumita Mukherjee, Samudrala Gourinath, Kumiko Nakada-Tsukui, Tomoyoshi Nozaki, Sunando Datta
Vps29 is the smallest subunit of retromer complex with metallo-phosphatase fold. Although the role of metal in Vps29 is in quest, its metal binding mutants has been reported to affect the localization of the retromer complex in human cells. In this study, we report the structural and thermodynamic consequences of these mutations in Vps29 from the protozoan parasite, Entamoeba histolytica (EhVps29). EhVps29 is a zinc binding protein as revealed by X-ray crystallography and isothermal titration calorimetry. The metal binding pocket of EhVps29 exhibits marked differences in its 3-dimensional architecture and metal coordination in comparison to its human homologs and other metallo-phosphatases...
September 12, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28887826/job-contenders-roles-of-the-%C3%AE-barrel-assembly-machinery-and-the-translocation-and-assembly-module-in-autotransporter-secretion
#12
REVIEW
Cécile Albenne, Raffaele Ieva
In Gram-negative bacteria, autotransporters secrete effector protein domains that are linked to virulence. Although they were once thought to be simple and autonomous secretion machines, mounting evidence reveals that multiple factors of the bacterial envelope are necessary for autotransporter assembly. Secretion across the outer membrane of their soluble effector "passenger domain" is promoted by the assembly of an outer membrane-spanning "β-barrel domain". Both reactions require BamA, an essential component of the β-barrel assembly machinery (BAM complex) that catalyzes the final reaction step by which outer membrane proteins are integrated into the lipid bilayer...
September 8, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28884498/aldo-keto-reductase-and-alcohol-dehydrogenase-contribute-to-benznidazole-natural-resistance-in-trypanosoma-cruzi
#13
Laura González, Paola García-Huertas, Omar Triana-Chávez, Gabriela Andrea García, Silvane Maria Fonseca Murta, Ana M Mejía-Jaramillo
The improvement of Chagas disease treatment is focused not only on the development of new drugs but also in understanding mechanisms of action and resistance to drugs conventionally used. Thus, some strategies aim to detect specific changes in proteins between sensitive and resistant parasites and to evaluate the role played in these processes by functional genomics. In this work, we used a natural Trypanosoma cruzi population resistant to benznidazole, which has clones with different susceptibilities to this drug without alterations in the NTR I gene...
September 7, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28884488/uniqueness-of-entamoeba-sulfur-metabolism-sulfolipid-metabolism-that-plays-pleiotropic-roles-in-the-parasitic-life-cycle
#14
Fumika Mi-Ichi, Tomofumi Miyamoto, Hiroki Yoshida
Sulfur metabolism is ubiquitous and terminally synthesizes various biomolecules that are crucial for organisms, such as sulfur-containing amino acids and co-factors, sulfolipids, and sulfated saccharides. Entamoeba histolytica, a protozoan parasite responsible for amoebiasis, possesses the unique sulfur metabolism features of atypical localization and its terminal product being limited to sulfolipids. Here, we present an overall scheme of E. histolytica sulfur metabolism by relating all sulfotransferases and sulfatases to their substrates and products...
September 7, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28876489/structural-mechanistic-insights-into-the-efficacy-of-non-classical-%C3%AE-lactamase-inhibitors-against-extensively-drug-resistant-stenotrophomonas-maltophilia-clinical-isolates
#15
Karina Calvopiña, Philip Hinchliffe, Jürgen Brem, Kate J Heesom, Samar Johnson, Ricky Cain, Christopher T Lohans, Colin W G Fishwick, Christopher J Schofield, James Spencer, Matthew B Avison
Clavulanic acid and avibactam are clinically deployed serine β-lactamase inhibitors, important as a defence against antibacterial resistance. Bicyclic boronates are recently discovered inhibitors of serine and some metallo β-lactamases. Here we show that avibactam and a bicyclic boronate inhibit L2 (serine β-lactamase) but not L1 (metallo β-lactamase) from the extensively drug resistant human pathogen Stenotrophomonas maltophilia. X-ray crystallography revealed that both inhibitors bind L2 by covalent attachment to the nucleophilic serine...
September 6, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28868744/a-putative-spermidine-synthase-interacts-with-flagellar-switch-protein-flim-and-regulates-motility-in-helicobacter-pylori
#16
Huawei Zhang, Kwok Ho Lam, Wendy Wai Ling Lam, Sandra Yuen Yuen Wong, Vera Sau Fong Chan, Shannon Wing Ngor Au
The flagellar motor is an important virulence factor in infection by many bacterial pathogens. Motor function can be modulated by chemotactic proteins and recently-appreciated proteins that are not part of the flagellar or chemotaxis systems. How these latter proteins affect flagellar activity is not fully understood. Here, we identified spermidine synthase SpeE as an interacting partner of switch protein FliM in Helicobacter pylori using pull-down assay and mass spectrometry. To understand how SpeE contributes to flagellar motility, a speE-null mutant was generated and its motility behavior was evaluated...
September 4, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28862774/deinococcus-radiodurans-dr1088-is-a-novel-recf-interacting-protein-that-stimulates-single-stranded-dna-annealing
#17
Kaiying Cheng, Guangzhi Xu, Hong Xu, Ye Zhao, Yuejin Hua
RecF, together with the recombination mediators RecO and RecR, is required in the RecFOR homologous recombination repair pathway in bacteria. In this study, a recF-dr1088 operon, which is highly conserved in the Deinococcus-Thermus phylum, was identified in Deinococcus radiodurans. Interaction between DRRecF and DR1088 was confirmed by yeast two-hybrid and pull-down assays. DR1088 exhibited some RecO-like biochemical properties including single/double-stranded DNA binding activity, ssDNA binding protein (SSB) replacement ability and ssDNA (with or without SSB) annealing activity...
September 1, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28861914/a-novel-mas-iii-selective-arsr-transcriptional-repressor
#18
Jian Chen, Venkadesh Sarkarai Nadar, Barry P Rosen
Microbial expression of genes for resistance to heavy metals and metalloids is usually transcriptionally regulated by the toxic ions themselves. Arsenic is a ubiquitous, naturally occurring toxic metalloid widely distributed in soil and groundwater. Microbes biotransform both arsenate (As(V)) and arsenite (As(III)) into more toxic methylated metabolites methylarsenite (MAs(III)) and dimethylarsenite (DMAs(III)). Environmental arsenic is sensed by members of the ArsR/SmtB family. The arsR gene is autoregulated and is typically part of an operon that contains other ars genes involved in arsenic detoxification...
September 1, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28857357/aspergillus-nidulans-baph-is-a-rab11-effector-that-connects-membranes-in-the-spitzenk%C3%A3-rper-with-basal-autophagy
#19
Mario Pinar, Miguel A Peñalva
Using affinity chromatography we identified the Aspergillus nidulans F-BAR-and-PH domain-containing protein BapH as a RabE(RAB11) effector. BapH localizes to the Spitzenkörper (SPK) in an F-actin- and Sec7-dependent manner, becoming cytosolic after inactivation of Trs120 in TRAPPII, the oligomeric GEF for RabE(RAB11) . Therefore RabE(RAB11) contributes to the recruitment of BapH to secretory vesicles in vivo. BapH has a close homologue, SlmA, which is related to yeast Slm1p/Slm2p, localizes to eisosomes and does not bind RabE(RAB11) ...
August 30, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28836704/a-novel-lipoate-attachment-enzyme-is-shared-by-plasmodium-and-chlamydia-species
#20
Gustavo A Afanador, Alfredo J Guerra, Russell P Swift, Ryan E Rodriguez, David Bartee, Krista A Matthews, Arne Schön, Ernesto Freire, Caren L Freel Meyers, Sean T Prigge
Lipoate is an essential cofactor for enzymes that are important for central metabolism and other processes. In malaria parasites, scavenged lipoate from the human host is required for survival. The Plasmodium falciparum mitochondrion contains two enzymes (PfLipL1 and PfLipL2) that are responsible for activating mitochondrial proteins through the covalent attachment of lipoate (lipoylation). Lipoylation occurs via a novel redox-gated mechanism that remains poorly understood. We show that PfLipL1 functions as a redox switch that determines which downstream proteins will be activated...
August 24, 2017: Molecular Microbiology
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