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Molecular Microbiology

Sara Manzanares-Estreder, Joan Espí-Bardisa, Benito Alarcón, Amparo Pascual-Ahuir, Markus Proft
Peroxisomes are dynamic organelles and the sole location for fatty acid β-oxidation in yeast cells. Here we report that peroxisomal function is crucial for the adaptation to salt stress, especially upon sugar limitation. Upon stress, multiple layers of control regulate the activity and the number of peroxisomes. Activated Hog1 MAP kinase triggers the induction of genes encoding enzymes for fatty acid activation, peroxisomal import and β-oxidation through the Adr1 transcriptional activator, which transiently associates with genes encoding fatty acid metabolic enzymes in a stress- and Hog1-dependent manner...
March 21, 2017: Molecular Microbiology
Alex Dajkovic, Benoit Tesson, Smita Chauhan, Pascal Courtin, Ruth Keary, Pierre Flores, Christian Marlière, Sergio Felipe, Marie-Pierre Chapot-Chartier, Rut Carballido-Lopez
The ability of excess Mg(2+) to compensate the absence of cell wall related genes in Bacillus subtilis has been known for a long time, but the mechanism has remained obscure. Here, we show that the rigidity of wild-type cells remains unaffected with excess Mg(2+) , but the proportion of amidated meso-diaminopimelic (mDAP) acid in their peptidoglycan (PG) is significantly reduced. We identify the amidotransferase AsnB as responsible for mDAP amidation and show that the gene encoding it is essential without added Mg(2+) ...
March 20, 2017: Molecular Microbiology
Shuang Sun, Bo Chen, Zi-Jing Jin, Lian Zhou, Yun-Ling Fang, Chitti Thawai, Giordano Rampioni, Ya-Wen He
Phenazines are important secondary metabolites that have been found to affect a broad spectrum of organisms. Two almost identical gene clusters phz1 and phz2 are responsible for phenazines biosynthesis in the rhizobacterium Pseudomonas aeruginosa PA1201. Here we show that the transcriptional regulator RsaL is a potent repressor of phenazine-1-carboxylic acid (PCA) biosynthesis. RsaL negatively regulates phz1 expression and positively regulates phz2 expression via multiple mechanisms. First, RsaL binds to a 25-bp DNA region within the phz1 promoter to directly repress phz1 expression...
March 18, 2017: Molecular Microbiology
Emilisa Frirdich, Jacob Biboy, Steven Huynh, Craig T Parker, Waldemar Vollmer, Erin C Gaynor
Campylobacter jejuni helical shape is important for colonization and host interactions with straight mutants having altered biological properties. Passage on calcofluor white (CFW) resulted in C. jejuni 81-176 isolates with morphology changes: either a straight morphology from frameshift mutations and single nucleotide polymorphisms in peptidoglycan hydrolase genes pgp1 or pgp2 or a reduction in curvature due a frameshift mutation in cjj81176_1105, a putative peptidoglycan endopeptidase. Shape defects were restored by complementation...
March 18, 2017: Molecular Microbiology
Marat R Sadykov, Jong-Sam Ahn, Todd J Widhelm, Valerie M Eckrich, Jennifer L Endres, Adam Driks, Gregory E Rutkowski, Kevin L Wingerd, Kenneth W Bayles
Numerous bacteria accumulate poly(3-hydroxybutyrate) (PHB) as an intracellular reservoir of carbon and energy in response to imbalanced nutritional conditions. In Bacillus spp., where PHB biosynthesis precedes the formation of the dormant cell type called the spore (sporulation), the direct link between PHB accumulation and efficiency of sporulation was observed in multiple studies. Although the idea of PHB as an intracellular carbon and energy source fueling sporulation was proposed several decades ago, the mechanisms underlying PHB contribution to sporulation have not been defined...
March 16, 2017: Molecular Microbiology
Andrew W Tanner, Valerie J Carabetta, Ryan J Martinie, Ameya A Mashruwala, Jeffrey M Boyd, Carsten Krebs, David Dubnau
During times of environmental insult, Bacillus subtilis undergoes developmental changes leading to biofilm formation, sporulation and competence. Each of these states is regulated in part by the phosphorylated form of the master response regulator Spo0A (Spo0A∼P). The phosphorylation state of Spo0A is controlled by a multi-component phosphorelay. RicA, RicF and RicT (previously YmcA, YlbF and YaaT) have been shown to be important regulatory proteins for multiple developmental fates. These proteins directly interact and form a stable complex, which has been proposed to accelerate the phosphorelay...
March 15, 2017: Molecular Microbiology
Gina L Lipscomb, Gerrit J Schut, Robert A Scott, Michael W W Adams
The sulfur response regulator, SurR, is among a handful of known redox-active transcriptional regulators. First characterized from the hyperthermophile Pyrococcus furiosus, it is unique to the archaeal order Thermococcales. P. furiosus has two modes of electron disposal. Hydrogen gas is produced when the organism is grown in the absence of elemental sulfur (S(0) ) and H2 S is produced when grown in its presence. Switching between these metabolic modes requires a rapid transcriptional response and this is orchestrated by SurR...
March 15, 2017: Molecular Microbiology
Miriam Rodríguez-González, Laura Kawasaki, Nancy Velázquez-Zavala, Eunice Domínguez-Martín, Abraham Trejo-Medecigo, Natalia Martagón, Emilio Espinoza-Simón, Araceli Vázquez-Ibarra, Laura Ongay-Larios, Dimitris Georgellis, Eulàlia de Nadal, Francesc Posas, Roberto Coria
The Kluyveromyces lactis SLN1 phosphorelay system includes the osmosensor histidine kinase Sln1, the phosphotransfer protein Ypd1 and the response regulator Ssk1. Here we show that K. lactis has a functional phosphorelay system. In vitro assays, using a heterolougus histidine kinase, show that the phosphate group is accepted by KlYpd1 and transfer to KlSsk1. Upon hyperosmotic stress the phosphorelay is inactivated, KlYpd1 is dephosphorylated in a KlSln1 dependent manner, and only the version of KlSsk1 that lacks the phosphate group interacts with the MAPKKK KlSsk2...
March 13, 2017: Molecular Microbiology
Facundo Rodriguez Ayala, Carlos Bauman, Marco Bartolini, Ester Saball, Marcela Salvarrey, Cecilia Leñini, Sebastián Cogliati, Mark Strauch, Roberto Grau
Bacterial adherence to extracellular matrix proteins (ECMp) plays important roles during host-pathogen interaction, however its genetic regulation remains poorly understood. yloA of the model bacterium Bacillus subtilis shows high homology to genes encoding fibronectin-binding proteins of Gram-positive pathogens. Here, we characterized the regulatory network of YloA-dependent adhesive properties of the probiotic B. subtilis natto (Bsn). YloA-proficient, but not YloA-deficient, Bsn specifically bound to ECMp in a concentration-dependent manner and were proficient in biofilm formation...
March 13, 2017: Molecular Microbiology
Matthew J Bush, Govind Chandra, Kim C Findlay, Mark J Buttner
BldD-(c-di-GMP) sits on top of the regulatory network that controls differentiation in Streptomyces, repressing a large regulon of developmental genes when the bacteria are growing vegetatively. In this way, BldD functions as an inhibitor that blocks the initiation of sporulation. Here we report the identification and characterization of BldO, an additional developmental repressor that acts to sustain vegetative growth and prevent entry into sporulation. However, unlike the pleiotropic regulator BldD, we show that BldO functions as the dedicated repressor of a single key target gene, whiB, and that deletion of bldO or constitutive expression of whiB is sufficient to induce precocious hypersporulation...
March 8, 2017: Molecular Microbiology
Kathryn J Turnbull, Kenn Gerdes
Antitoxins encoded by type II toxin - antitoxin (TA) modules neutralize cognate toxins by direct protein - protein contact and in addition, regulate TA operon transcription by binding to operators in the promoter regions. On top of the simple negative feed-back regulation, canonical type II TA operons are regulated by a mechanism called "Conditional Cooperativity" (CC). In CC, the cellular toxin:antitoxin (T:A) ratio controls the transcription-rate such that low T:A ratios favour repression and high T:A ratios favour de-repression of TA operon transcription...
March 7, 2017: Molecular Microbiology
Laura Teichmann, Chiliang Chen, Tamara Hoffmann, Sander H J Smits, Lutz Schmitt, Erhard Bremer
The ABC-transporters OpuB and OpuC from Bacillus subtilis function as osmoprotectant import systems. Their structural genes have most likely evolved through a duplication event but the two transporters are remarkably different in their substrate profile. OpuB possesses narrow substrate specificity, while OpuC is promiscuous. We assessed the functionality of hybrids between these two ABC-transporters by reciprocally exchanging the coding regions for the OpuBC and OpuCC substrate-binding proteins between the corresponding opuB and opuC operons...
March 3, 2017: Molecular Microbiology
Johan Paulsson, Meriem El Karoui, Monica Lindell, Diarmaid Hughes
Gene conversion, non-reciprocal transfer from one homologous sequence to another, is a major force in evolutionary dynamics, promoting co-evolution in gene families, and maintaining similarities between repeated genes. However, the properties of the transfer - where it initiates, how far it proceeds, and how the resulting conversion tracts are affected by mismatch repair - are not well understood. Here we use the duplicate tuf genes in Salmonella as a quantitatively tractable model system for gene conversion...
March 3, 2017: Molecular Microbiology
Megumi Nagano-Shoji, Yuma Hamamoto, Yuta Mizuno, Ayuka Yamada, Masaki Kikuchi, Mikako Shirouzu, Takashi Umehara, Minoru Yoshida, Makoto Nishiyama, Saori Kosono
Protein Nε-acylation is emerging as a ubiquitous post-translational modification. In Corynebacterium glutamicum, which is utilized for industrial production of L-glutamate, the levels of protein acetylation and succinylation change drastically under the conditions that induce glutamate overproduction. Here, we characterized the acylation of phosphoenolpyruvate carboxylase (PEPC), an anaplerotic enzyme that supplies oxaloacetate for glutamate overproduction. We showed that acetylation of PEPC at lysine 653 decreased enzymatic activity, leading to reduced glutamate production...
March 3, 2017: Molecular Microbiology
Koichiro Akiyama, Yohei Hizukuri, Yoshinori Akiyama
RseP, an Escherichia coli S2P family intramembrane cleaving protease, is involved in regulation of the extracytoplasmic stress response and membrane quality control through specific cleavage of substrates. Recent research suggested that the PDZ domains and the MRE β-loop (membrane-reentrant β-loop) are involved in substrate discrimination; the former would serve to prevent cleavage of substrates with a large periplasmic domain, whereas the latter would directly interact with the substrate's transmembrane segment and induce its conformational change...
March 3, 2017: Molecular Microbiology
Hannes Breddermann, Karin Schnetz
LeuO is a conserved LysR-type transcription factor of pleiotropic function in Enterobacteria. Regulation of the leuO gene has been best studied in Escherichia coli and Salmonella enterica. Its expression is silenced by the nucleoid-associated proteins H-NS and StpA, autoregulated by LeuO, and in E. coli activated by the transcription regulator BglJ-RcsB. However, signals which induce leuO expression remain unknown. Here we show that LrhA, a conserved LysR-type transcription regulator, activates leuO in E. coli...
March 2, 2017: Molecular Microbiology
Julia E Martin, Katherine A Edmonds, Kevin E Bruce, Gregory C Campanello, Bart A Eijkelkamp, Erin B Brazel, Christopher A McDevitt, Malcolm E Winkler, David P Giedroc
Zinc is an essential trace element that serves as a catalytic cofactor in metalloenzymes and a structural element in proteins involved in general metabolism and cellular defenses of pathogenic bacteria. Despite its importance, high zinc levels can impair cellular processes, inhibiting growth of many pathogenic bacteria, including the major respiratory pathogen Streptococcus pneumoniae. Zinc intoxication is prevented in S. pneumoniae by expression of the zinc exporter CzcD, whose expression is activated by the novel TetR-family transcriptional zinc-sensing regulator SczA...
March 1, 2017: Molecular Microbiology
Jackson A Buss, Nick T Peters, Jie Xiao, Thomas G Bernhardt
Cell division in Escherichia coli begins with the polymerization of FtsZ into a ring-like structure, the Z-ring, at midcell. All other division proteins are thought to require the Z-ring for recruitment to the future division site. Here, we report that the Z-ring associated proteins ZapA and ZapB form FtsZ-independent structures at midcell. Upon Z-ring disruption by the FtsZ polymerization antagonist SulA, ZapA remained at midcell as a cloud-like accumulation. Using ZapA(N60Y), a variant defective for interaction with FtsZ, it was established that these ZapA structures form without a connection to the Z-ring...
March 1, 2017: Molecular Microbiology
Rafael Luis Kessler, Víctor Tulio Contreras, Newmar Pinto Marliére, Alessandra Aparecida Guarneri, Luz Helena Villamizar Silva, Giovanny Augusto Camacho Antevere Mazzarotto, Michel Batista, Vanete Thomaz Soccol, Marco Aurelio Krieger, Christian Macagnan Probst
Trypanosoma cruzi, the etiologic agent of Chagas disease, has a complex life cycle in which four distinct developmental forms alternate between the insect vector and the mammalian host. It is assumed that replicating epimastigotes present in the insect gut are not infective to mammalian host, a paradigm corroborated by the widely acknowledged fact that only this stage is susceptible to the complement system. In the present work, we establish a T. cruzi in vitro and in vivo epimastigogenesis model to analyze the biological aspects of recently differentiated epimastigotes (rdEpi)...
February 27, 2017: Molecular Microbiology
Cassandra Terry, Shuo Jiang, David S Radford, Wan Qiang, Svetomir Tzokov, Anne Moir, Per A Bullough
Bacteria of the genera Bacillus and Clostridium form highly resistant spores, which in the case of some pathogens act as the infectious agents. An exosporium forms the outermost layer of some spores; it plays roles in protection, adhesion, dissemination, host targeting in pathogens, and germination control. The exosporium of the Bacillus cereus group, including the anthrax pathogen, contains a 2D-crystalline basal layer, overlaid by a hairy nap. BclA and related proteins form the hairy nap, and require ExsFA (BxpB) for their localisation on the basal layer...
February 18, 2017: Molecular Microbiology
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