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Molecular Microbiology

Yidong Yu, Adriana Blachowicz, Cornelia Will, Edyta Szewczyk, Steven Glenn, Sabrina Gensberger-Reigl, Minou Nowrousian, Clay C C Wang, Sven Krappmann
In the human pathogenic mold Aspergillus fumigatus, sexual identity is determined by the mating-type idiomorphs MAT1-1 and MAT1-2 residing at the MAT locus. Upon crossing of compatible partners, a heterothallic mating is executed to eventually form cleistothecia that contain recombinant ascospores. Given that the MAT1 gene products are DNA binding master regulators that govern this complex developmental process, we monitored the MAT1-driven transcriptomes of A. fumigatus by conditional overexpression of either MAT1 gene followed by RNA-seq analyses...
September 21, 2018: Molecular Microbiology
Natalie Stoian, James Kaganjo, Jill Zeilstra-Ryalls
Strains of the phototrophic alpha-proteobacterium Rhodobacter sphaeroides vary in the number of enzymes catalyzing the formation of 5-aminolevulinic acid (ALA synthases) that are encoded in their genomes. All have hemA, but not all have hemT. This study compared transcription of these genes, and also properties of their products among three wild type strains; 2.4.3 has hemA alone, 2.4.1 and 2.4.9 have both hemA and hemT. Using lacZ reporter plasmids all hemA genes were found to be upregulated under anaerobic conditions, but induction amplitudes differ...
September 19, 2018: Molecular Microbiology
Jaana Männik, Bryant E Walker, Jaan Männik
FtsZ is the key regulator of bacterial cell division. It initiates division by forming a dynamic ring-like structure, the Z-ring, at the mid-cell. What triggers the formation of the Z-ring during the cell cycle is poorly understood. In Escherichia coli, the common view is that FtsZ concentration is constant throughout its doubling time and therefore regulation of assembly is controlled by some yet-to-be-identified protein-protein interactions. Using a newly developed functional, fluorescent FtsZ reporter, we performed a quantitative analysis of the FtsZ concentration throughout the cell cycle under slow growth conditions...
September 19, 2018: Molecular Microbiology
Victoria Dyer, Holger Brüggemann, Meike Sörensen, Anja A Kühl, Kirstin Hoffman, Volker Brinkmann, Maria Del Mar Reines, Stephanie Zimmerman, Thomas F Meyer, Manuel Koch
The human gastric pathogen Helicobacter pylori occurs in two basic variants, either exhibiting a functional cagPAI-encoded type-4-secretion-system (T4SS) or not. Only a few cagPAI positive strains have been successfully adapted for long-term infection of mice, including the pre-mouse Sydney strain 1 (PMSS1). Here we confirm that PMSS1 induces gastric inflammation and neutrophil infiltration in mice, progressing to intestinal metaplasia. Complete genome analysis of PMSS1 revealed 1,423 coding sequences, encompassing the cagPAI gene cluster and, unusually, location of the cytotoxin-associated gene A (cagA) approximately 15 kb downstream of the island...
September 19, 2018: Molecular Microbiology
Sebastian S Broendum, Ashley M Buckle, Sheena McGowan
Bacteriophage-encoded endolysins can recognize and bind specific bacteria, and act to cleave the glycosidic and/or amide bonds in the peptidoglycan bacterial cell wall. Cleavage of the cell wall generally results in the death of the bacteria. Their utility as bacteriolytic agents could be exploited for human and veterinary medicines and as well as various biotechnological applications. As interest grows in the commercial uses of these proteins, there has been much effort to successfully employ rational design and engineering to produce endolysins with bespoke properties...
September 19, 2018: Molecular Microbiology
Lu Liang, Ian F Connerton
The carrier state is an alternative bacteriophage life cycle by which virulent bacteriophage can persist in association with host bacteria. Campylobacter jejuni carrier state strains exhibit growth phase dependent motility due to a truncated flagella phenotype. Genome sequencing identified a T368A substitution in the G3 domain of the SRP-like GTPase FlhF from C. jejuni PT14CP30A carrier state strains, which we hypothesized to be the cause of the complex motility phenotype. We have analyzed the role of this mutation in C...
September 19, 2018: Molecular Microbiology
Raquel S Negreiros, Noelia Lander, Guozhong Huang, Ciro D Cordeiro, Stephanie A Smith, James H Morrissey, Roberto Docampo
Inorganic polyphosphate (polyP) is a polymer of three to hundreds of phosphate units bound by high-energy phosphoanhydride bonds and present from bacteria to humans. Most polyP in trypanosomatids is concentrated in acidocalcisomes, acidic calcium stores that possess a number of pumps, exchangers, and channels, and are important for their survival. In this work, using polyP as bait we identified > 25 putative protein targets in cell lysates of both Trypanosoma cruzi and T. brucei. Gene ontology analysis of the binding partners found a significant over-representation of nucleolar and glycosomal proteins...
September 19, 2018: Molecular Microbiology
Lucas A Meirelles, Dianne K Newman
Pseudomonas aeruginosa, an opportunistic pathogen, produces redox-active pigments called phenazines. Pyocyanin (PYO, the blue phenazine) plays an important role during biofilm development. Paradoxically, PYO auto-poisoning can stimulate cell death and release of extracellular DNA (eDNA), yet PYO can also promote survival within biofilms when cells are oxidant-limited. Here we identify the environmental and physiological conditions in planktonic culture that promote PYO-mediated cell death. We demonstrate that PYO auto-poisoning is enhanced when cells are starved for carbon...
September 19, 2018: Molecular Microbiology
Mareike Lembke, Nina Pennetzdorfer, Sarah Tutz, Michael Koller, Dina Vorkapic, Jun Zhu, Stefan Schild, Joachim Reidl
In Vibrio cholerae, virulence gene expression is regulated by a transmembrane-localized transcription factor complex designated as ToxRS. ToxR harbours two cysteines in the periplasmic domain that can form inter- and intramolecular disulfide bonds. In this study, we investigated the σE -dependent inner membrane proteolysis of ToxR, which occurs via the periplasmic-localized proteases DegS and DegP. Both proteases respond to the redox state of the two cysteine thiol groups of ToxR. Interestingly, in the presence of sodium deoxycholate, ToxR proteolysis is blocked independently of ToxS, whereas ToxR activation by bile salts requires ToxS function...
September 14, 2018: Molecular Microbiology
Margarita Kalamara, Mihael Špacapan, Ines Mandic-Mulec, Nicola R Stanley-Wall
Here we review the multiple mechanisms that the Gram-positive bacterium Bacillus subtilis uses to allow it to communicate between cells and establish community structures. The modes of action that are used are highly varied and include routes that sense pheromone levels during quorum sensing and control gene regulation, the intimate coupling of cells via nanotubes to share cytoplasmic contents, and long range electrical signalling to couple metabolic processes both within and between biofilms. We explore the ability of B...
September 14, 2018: Molecular Microbiology
Shanti Swaroop Srivastava, Rajeev Raman, Uday Kiran, Rupsi Garg, Swathi Chadalawada, Asmita D Pawar, Rajan Sankaranarayanan, Yogendra Sharma
We describe a set of proteins in which a βγ-crystallin domain pairs with an Ig-like domain, and which are confined to microbes, like bacteria, slime molds, and fungi. DdCAD-1 (Ca2+ -dependent cell adhesion molecule-1) and APP (Abundant Perithecial Protein) represent this class of molecules. Using the crystal structure of APP-NTD (N-terminal domain of APP), we describe its mode of Ca2+ binding and provide a generalized theme for correct identification of the Ca2+ -binding site within this class of molecules...
September 14, 2018: Molecular Microbiology
Christin Köbler, Siri-Jasmin Schultz, Dominik Kopp, Karsten Voigt, Annegret Wilde
Cyanobacteria exhibit rhythmic gene expression with a period length of 24 hours to adapt to daily environmental changes. In the model organism Synechococcus elongatus PCC 7942 the central oscillator consists of the three proteins KaiA, KaiB and KaiC and utilizes the histidine kinase SasA and its response regulator RpaA as output-signaling pathway. Synechocystis sp. PCC 6803 contains in addition to the canonical kaiAB1C1 gene cluster two further homologs of the kaiB and kaiC genes. Here we demonstrate that the SasA-RpaA system interacts with the KaiAB1C1 core oscillator only...
September 14, 2018: Molecular Microbiology
Roxie C Girardin, Guangchun Bai, Jie He, Haixin Sui, Kathleen A McDonough
Gene regulatory networks used by Mycobacterium tuberculosis (Mtb) during infection include many genes of unknown function, confounding efforts to determine their roles in Mtb biology. Rv1265 encodes a conserved hypothetical protein that is expressed during infection and in response to elevated levels of cyclic AMP. Here, we report that Rv1265 is a novel auto-inhibitory ATP-binding transcription factor that up-regulates expression of the small non-coding RNA Mcr11, and propose that Rv1265 be named ATP-binding mcr11 regulator (AbmR)...
September 12, 2018: Molecular Microbiology
Stephen Hayes, Renaud Vincentelli, Jennifer Mahony, Arjen Nauta, Laurie Ramond, Gabriele A Lugli, Marco Ventura, Douwe van Sinderen, Christian Cambillau
With increasing numbers of 3D structures of bacteriophage components, combined with powerful in silico predictive tools, it has become possible to decipher the structural assembly and associated functionality of phage adhesion devices. Recently, decorations have been reported in the tail and neck passage structures of members of the so-called 936 group of lactococcal siphophages. In the current report, using bioinformatic analysis we identified a conserved carbohydrate binding module (CBM) among many of the virion baseplate Dit components, in addition to the CBM present in the 'classical' receptor binding proteins (RBPs)...
September 11, 2018: Molecular Microbiology
Wiphawee Leesutthiphonchai, Howard S Judelson
MADS-box transcription factors play significant roles in eukaryotes, but have not yet been characterized in oomycetes. Here, we describe a MADS-box protein from Phytophthora infestans, which causes late blight of potato. P. infestans and most other oomycetes express a single MADS-box gene. PiMADS is not transcribed during vegetative growth, but is induced early during asexual sporulation. Its mRNA levels oscillate in response to light, which suppresses sporulation. The protein was not detected in nonsporulating mycelia, but was found in sporulating mycelia and spores...
September 8, 2018: Molecular Microbiology
Nicole R Ratib, Erich Y Sabio, Carolina Mendoza, Melanie J Barnett, Sarah B Clover, Jesus A Ortega, Francesca M Dela Cruz, David Balderas, Holly White, Sharon R Long, Esther J Chen
ExoS/ChvI two-component signaling in the nitrogen-fixing α-proteobacterium Sinorhizobium meliloti is required for symbiosis and regulates exopolysaccharide production, motility, cell envelope integrity, and nutrient utilization in free-living bacteria. However, identification of many ExoS/ChvI direct transcriptional target genes has remained elusive. Here, we performed chromatin immunoprecipitation followed by microarray analysis (chIP-chip) to globally identify DNA regions bound by ChvI protein in S. meliloti...
September 7, 2018: Molecular Microbiology
Hao Yu, Guang Liu, Gong Zhao, Wenyue Hu, Geng Wu, Zixin Deng, Xinyi He
Streptomyces species have been valuable models for understanding the phenomenon of DNA phosphorothioation in which sulfur replaces a non-bridging oxygen in the phosphate backbone of DNA. We previously reported that the restriction endonuclease ScoMcrA from S. coelicolor cleaves phosphorothioate DNA and Dcm-methylated DNA at sites 16-28 nucleotides away from the modification sites. However, cleavage of modified DNA by ScoMcrA is always incomplete and accompanied by severe promiscuous activity on unmodified DNA...
September 5, 2018: Molecular Microbiology
Matthew J Bush
The WhiB-like (Wbl) family of proteins are exclusively found in Actinobacteria. Wbls have been shown to play key roles in virulence and antibiotic resistance in Mycobacteria and Corynebacteria, reflecting their importance during infection by the human pathogens Mycobacterium tuberculosis, Mycobacterium leprae and Corynebacterium diphtheriae. In the antibiotic-producing Streptomyces, several Wbls have important roles in the regulation of morphological differentiation, including WhiB, a protein that controls the initiation of sporulation septation and the founding member of the Wbl family...
September 4, 2018: Molecular Microbiology
Filipa Nunes, Catarina Fernandes, Carolina Freitas, Eleonora Marini, Mónica Serrano, Charles P Moran, Patrick Eichenberger, Adriano O Henriques
During sporulation in Bacillus subtilis, a group of mother cell-specific proteins guides the assembly of the coat, a multiprotein structure that protects the spore and influences many of its environmental interactions. SafA and CotE behave as party hubs, governing assembly of the inner and outer coat layers. Targeting of coat proteins to the developing spore is followed by encasement. Encasement by SafA and CotE requires E, a region of 11 amino acids in the encasement protein SpoVID, with which CotE interacts directly...
August 31, 2018: Molecular Microbiology
Youngchang Kim, Gekleng Chhor, Ching-Sung Tsai, James B Winans, Robert Jedrzejczak, Andrzej Joachimiak, Stephen C Winans
LysR-type transcriptional regulators (LTTRs) generally bind to target promoters in two conformations, depending on the availability of inducing ligands. OccR is an LTTR that regulates the octopine catabolism operon of Agrobacterium tumefaciens. OccR binds to a site located between the divergent occQ and occR promoters. Octopine triggers a conformational change that activates the occQ promoter, and does not affect autorepression. This change shortens the length of bound DNA and relaxes a high-angle DNA bend...
August 31, 2018: Molecular Microbiology
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