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Molecular Microbiology

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https://www.readbyqxmd.com/read/28544028/subcellular-compartmentation-interdependency-and-dynamics-of-the-cyclic-amp-dependent-pka-subunits-during-pathogenic-differentiation-in-rice-blast
#1
Poonguzhali Selvaraj, Tham Hong Fai, Ravikrishna Ramanujam, Naweed I Naqvi
The cAMP-dependent PKA signaling plays a central role in growth, asexual development and pathogenesis in fungal pathogens. Here, we functionally characterized RPKA, the regulatory subunit of cAMP/PKA and studied the dynamics and organization of the PKA subunits in the rice blast pathogen Magnaporthe oryzae. The RPKA subunit was essential for proper vegetative growth, asexual sporulation and surface hydrophobicity in M. oryzae. A spontaneous suppressor mutation, SMR19, that restored growth and conidiation in the RPKA deletion mutant was isolated and characterized...
May 20, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28517364/a-cryptic-pigment-biosynthetic-pathway-uncovered-by-heterologous-expression-is-essential-for-conidial-development-in-pestalotiopsis-fici
#2
Peng Zhang, Xiuna Wang, Aili Fan, Yanjing Zheng, Xingzhong Liu, Shihua Wang, Huixi Zou, Berl R Oakley, Nancy P Keller, Wen-Bing Yin
Spore pigmentation is very common in the fungal kingdom. The best studied pigment in fungi is melanin which coats the surface of single cell spores. What and how pigments function in a fungal species with multiple cell conidia is poorly understood. Here, we identified and deleted a polyketide synthase (PKS) gene PfmaE and showed that it is essential for multicellular conidial pigmentation and development in a plant endophytic fungus, Pestalotiopsis fici. To further characterize the melanin pathway, we utilized an advanced Aspergillus nidulans heterologous system for the expression of the PKS PfmaE and the Pfma gene cluster...
May 18, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28517109/the-studies-of-para-and-parb-dynamics-reveal-asymmetry-of-chromosome-segregation-in-mycobacteria
#3
Katarzyna Ginda, Isabella Santi, Djenet Bousbaine, Jolanta Zakrzewska-Czerwińska, Dagmara Jakimowicz, John McKinney
Active segregation of bacterial chromosomes usually involves the action of ParB proteins, which bind in proximity of chromosomal origin (oriC) regions forming nucleoprotein complexes - segrosomes. Newly duplicated segrosomes are moved either uni- or bidirectionally by the action of ATPases - ParA proteins. In Mycobacterium smegmatis the oriC region is located in an off-centred position and newly replicated segrosomes are segregated toward cell poles. The elimination of M. smegmatis ParA and/or ParB leads to chromosome segregation defects...
May 18, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28513100/function-of-bacteriophage-g7c-esterase-tailspike-in-host-cell-adsorption
#4
Nikolai S Prokhorov, Cristian Riccio, Evelina L Zdorovenko, Mikhail M Shneider, Christopher Browning, Yuriy A Knirel, Petr G Leiman, Andrey V Letarov
Bacteriophages recognize and bind to their hosts with the help of receptor-binding proteins (RBPs) that emanate from the phage particle in the form of fibers or tailspikes. RBPs show a great variability in their shapes, sizes, and location on the particle. Some RBPs are known to depolymerize surface polysaccharides of the host while others show no enzymatic activity. Here we report that both RBPs of podovirus G7C - tailspikes gp63.1 and gp66 - are essential for infection of its natural host bacterium E. coli 4s that populates the equine intestinal tract...
May 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28513097/evidence-for-a-peptidoglycan-like-structure-in-orientia-tsutsugamushi
#5
Sharanjeet Atwal, Suparat Giengkam, Suwittra Chaemchuen, Jack Dorling, Nont Kosaisawe, Michael VanNieuwenhze, Somponnat Sampattavanich, Peter Schumann, Jeanne Salje
Bacterial cell walls are composed of the large cross-linked macromolecule peptidoglycan, which maintains cell shape and is responsible for resisting osmotic stresses. This is a highly conserved structure and the target of numerous antibiotics. Obligate intracellular bacteria are an unusual group of organisms that have evolved to replicate exclusively within the cytoplasm or vacuole of a eukaryotic cell. They tend to have reduced amounts of peptidoglycan, likely due to the fact that their growth and division takes place within an osmotically protected environment, and also due to a drive to reduce activation of the host immune response...
May 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28509398/the-multi-component-antirestriction-system-of-phage-p1-is-linked-to-capsid-morphogenesis
#6
Denish Piya, Leonardo Vara, William K Russell, Ry Young, Jason J Gill
Bacterial Type I restriction-modification (R-M) systems present a major barrier to foreign DNA entering the bacterial cell. The temperate phage P1 packages several proteins into the virion that protect the phage DNA from host restriction. Isogenic P1 deletion mutants were used to reconstitute the previously described restriction phenotypes associated with darA and darB. While P1ΔdarA and P1ΔdarB produced the expected phenotypes, deletions of adjacent genes hdf and ddrA also produced darA-like phenotypes and deletion of ulx produced a darB-like phenotype, implicating several new proteins of previously unknown function in the P1 dar antirestriction system...
May 16, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28509393/nmea-a-novel-efflux-transporter-specific-for-nucleobases-and-nucleosides-contributes-to-metal-resistance-in-aspergillus-nidulans
#7
Sofia Balaska, Vassilios Myrianthopoulos, Martha Tselika, Dimitris G Hatzinikolaou, Emmanuel Mikros, George Diallinas
Through Minos transposon mutagenesis we obtained A. nidulans mutants resistant to 5-fluorouracil due to insertions into the upstream region of the uncharacterized gene nmeA, encoding a Major Facilitator Superfamily (MFS) transporter. Minos transpositions increased nmeA transcription, which is otherwise extremely low under all conditions tested. To dissect the function of NmeA we used strains overexpressing or genetically lacking the nmeA gene. Strains overexpressing NmeA are resistant to toxic purine analogues, but also, to cadmium, zinc and borate, whereas an isogenic nmeAΔ null mutant exhibits increased sensitivity to these compounds...
May 16, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28508453/tetr-dependent-gene-regulation-in-intracellular-listeria-monocytogenes-demonstrates-the-spatiotemporal-surface-distribution-of-acta
#8
Sibylle Schmitter, Lars Fieseler, Jochen Klumpp, Ralph Bertram, Martin J Loessner
To enable specific and tightly controlled gene expression both in-vitro and during the intracellular lifecycle of the pathogen Listeria monocytogenes, a TetR-dependent genetic induction system was developed. Highest concentration of cytoplasmic TetR and best repression of tetO-controlled genes was obtained by tetR expression from the synthetic promoter Pt17 . Anhydrotetracycline (ATc) as inducer permitted concentration-dependent, fine-tuned expression of genes under control of the tetO operator and a suitable promoter...
May 15, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28508421/subversion-of-host-kinases-a-key-network-in-cellular-signaling-hijacked-by-helicobacter-pylori-caga
#9
REVIEW
Nicole Tegtmeyer, Matthias Neddermann, Carmen Isabell Asche, Steffen Backert
Helicobacter pylori is a paradigm of persistent pathogens and major risk factor for developing severe diseases including adenocarcinoma in the human stomach. An important bacterial factor linked to gastric disease progression is the cag pathogenicity island-encoded type-IV secretion system (T4SS) effector protein CagA. Translocated CagA undergoes tyrosine phosphorylation at EPIYA-motifs and then activates or inactivates multiple host signaling proteins in a phosphorylation-dependent and phosphorylation-independent fashion...
May 15, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28486768/the-trans-envelope-architecture-and-function-of-the-type-2-secretion-system-new-insights-raising-new-questions
#10
REVIEW
Jenny-Lee Thomassin, Javier Santos Moreno, Ingrid Guilvout, Guy Tran Van Nhieu, Olivera Francetic
Nanomachines belonging to the type IV filament (Tff) superfamily serve a variety of cellular functions in prokaryotes, including motility, adhesion, electrical conductance, competence and secretion. The type 2 secretion system (T2SS) Tff member assembles a short filament called pseudopilus that promotes the secretion of folded proteins from the periplasm across the outer membrane of Gram-negative bacteria. A combination of structural, biochemical, imaging, computational and in vivo approaches had led to a working model for the assembled nanomachine...
May 9, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28470834/the-n-succinyl-l-l-diaminopimelic-acid-desuccinylase-dape-acts-through-zapb-to-promote-septum-formation-in-escherichia-coli
#11
Shishen Du, Joe Lutkenhaus
Spatial regulation of cell division in E. coli occurs at the stage of Z ring formation. It consists of negative (the Min and NO systems) and positive (Ter signal mediated by MatP/ZapA/ZapB) regulators. Here, we find that N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) facilitates functional Z ring formation by strengthening the Ter signal via ZapB. DapE depends on ZapB to localize to the Z ring and its overproduction suppresses the division defect caused by loss of both the Min and NO systems. DapE shows a strong interaction with ZapB and requires the presence of ZapB to exert its function in division...
May 4, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28470798/alternative-pathways-for-escherichia-coli-biofilm-formation-revealed-by-srna-overproduction
#12
Ashley Parker, Suanur Cureoglu, Nicholas De Lay, Nadim Majdalani, Susan Gottesman
Small regulatory RNAs have major roles in many regulatory circuits in Escherichia coli and other bacteria, including the transition from planktonic to biofilm growth. We tested Hfq-dependent sRNAs in E. coli for their ability, when overproduced, to inhibit or stimulate biofilm formation, in two different growth media. We identify two mutually exclusive pathways for biofilm formation. In LB, PgaA, encoding an adhesion export protein, played a critical role; biofilm was independent of the general stress factor RpoS or CsgD, regulator of curli and other biofilm genes...
May 4, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28464471/chemical-activation-of-adenylyl-cyclase-rv1625c-inhibits-growth-of-mycobacterium-tuberculosis-on-cholesterol-and-modulates-intramacrophage-signaling
#13
Richard M Johnson, Guangchun Bai, Christopher M DeMott, Nilesh K Banavali, Christine R Montague, Caroline Moon, Alexander Shekhtman, Brian VanderVen, Kathleen A McDonough
Mycobacterium tuberculosis (Mtb) uses a complex 3', 5'-cyclic AMP (cAMP) signaling network to sense and respond to changing environments encountered during infection, so perturbation of cAMP signaling might be leveraged to disrupt Mtb pathogenesis. However, understanding of cAMP signaling pathways is hindered by the presence of at least 15 distinct adenylyl cyclases (ACs). Recently, the small molecule V-58 was shown to inhibit Mtb replication within macrophages and stimulate cAMP production in Mtb. Here we determined that V-58 rapidly and directly activates Mtb AC Rv1625c to produce high levels of cAMP regardless of the bacterial environment or growth medium...
May 2, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28464377/bile-salts-and-alkaline-ph-reciprocally-modulate-the-interaction-between-the-periplasmic-domains-of-vibrio-cholerae-toxr-and-toxs
#14
Charles R Midgett, Salvador Almagro-Moreno, Maria Pellegrini, Ronald K Taylor, Karen Skorupski, F Jon Kull
ToxR is a transmembrane transcription factor that is essential for virulence gene expression and human colonization by Vibrio cholerae. ToxR requires its operon partner ToxS, a periplasmic integral membrane protein, for full activity. These two proteins are thought to interact through their respective periplasmic domains, ToxRp and ToxSp. In addition, ToxR is thought to be responsive to various environmental cues, such as bile salts and alkaline pH, but how these factors influence ToxR is not yet understood...
May 2, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28452085/use-of-chimeric-type-iv-secretion-systems-to-define-contributions-of-outer-membrane-subassemblies-for-contact-dependent-translocation
#15
Jay E Gordon, Tiago R D Costa, Roosheel S Patel, Christian Gonzalez-Rivera, Mayukh K Sarkar, Elena V Orlova, Gabriel Waksman, Peter J Christie
Recent studies have shown that conjugation systems of Gram-negative bacteria are composed of distinct inner and outer membrane core complexes (IMCs and OMCCs, respectively). Here, we functionally characterized the OMCC, focusing first on a cap domain that forms a channel across the outer membrane. Strikingly, the OMCC caps of the Escherichia coli pKM101 Tra and Agrobacterium tumefaciens VirB/VirD4 systems are completely dispensable for substrate transfer, but required for formation of conjugative pili. The pKM101 OMCC cap and extended pilus also are dispensable for activation of a Pseudomonas aeruginosa type VI secretion system (T6SS)...
April 27, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28431199/staphylococcus-aureus-nitric-oxide-synthase-sanos-modulates-aerobic-respiratory-metabolism-and-cell-physiology
#16
Austin B Mogen, Ronan K Carroll, Kimberly L James, Genevy Lima, Dona Silva, Jeffrey A Culver, Christopher Petucci, Lindsey N Shaw, Kelly C Rice
Nitric oxide (NO) is generated from arginine and oxygen via NO synthase (NOS). Staphylococcus aureus NOS (saNOS) has previously been shown to affect virulence and resistance to exogenous oxidative stress, yet the exact mechanism is unknown. Herein, a previously undescribed role of saNOS in S. aureus aerobic physiology was reported. Specifically, aerobic S. aureus nos mutant cultures presented with elevated endogenous reactive oxygen species (ROS) and superoxide levels, as well as increased membrane potential, increased respiratory dehydrogenase activity and slightly elevated oxygen consumption...
April 21, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28431189/to-cure-or-not-to-cure-differential-effects-of-the-chaperone-sorting-factor-cur1-on-yeast-prions-are-mediated-by-the-chaperone-sis1
#17
Yury A Barbitoff, Andrew G Matveenko, Svetlana E Moskalenko, Olga M Zemlyanko, Gary P Newnam, Ayesha Patel, Tatiana A Chernova, Yury O Chernoff, Galina A Zhouravleva
Yeast self-perpetuating protein aggregates (prions) provide a convenient model for studying various components of the cellular protein quality control system. Molecular chaperones and chaperone-sorting factors, such as yeast Cur1 protein, play key role in proteostasis via tight control of partitioning and recycling of misfolded proteins. In this study, we show that, despite the previously described ability of Cur1 to antagonize the yeast prion [URE3], it enhances propagation and phenotypic manifestation of another prion, [PSI(+) ]...
April 21, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28422332/biofilm-dispersal-multiple-elaborate-strategies-for-dissemination-of-bacteria-with-unique-properties
#18
REVIEW
Cyril Guilhen, Christiane Forestier, Damien Balestrino
In most environments, microorganisms evolve in a sessile mode of growth, designated as biofilm, which is characterized by cells embedded in a self-produced extracellular matrix. Although a biofilm is commonly described as a "cozy house" where resident bacteria are protected from aggression, bacteria are able to break their biofilm bonds and escape to colonize new environments. This regulated process is observed in a wide variety of species; it is referred to as biofilm dispersal, and is triggered in response to various environmental and biological signals...
April 19, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28419631/tgpl2-a-patatin-like-phospholipase-domain-containing-protein-is-involved-in-the-maintenance-of-apicoplast-lipids-homeostasis-in-toxoplasma
#19
Maude F Lévêque, Laurence Berry, Yoshiki Yamaryo-Botté, Hoa Mai Nguyen, Marine Galera, Cyrille Y Botté, Sébastien Besteiro
Patatin-like phospholipases are involved in numerous cellular functions, including lipid metabolism and membranes remodeling. The patatin-like catalytic domain, whose phospholipase activity relies on a serine-aspartate dyad and an anion binding box, is widely spread among prokaryotes and eukaryotes. We describe TgPL2, a novel patatin-like phospholipase domain-containing protein from the parasitic protist Toxoplasma gondii. TgPL2 is a large protein, in which the key motifs for enzymatic activity are conserved in the patatin-like domain...
April 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28419603/assembly-and-activation-of-the-escherichia-coli-divisome
#20
REVIEW
Shishen Du, Joe Lutkenhaus
Cell division in Escherichia coli is mediated by a large protein complex called the divisome. Most of the divisome proteins have been identified, but how they assemble onto the Z ring scaffold to form the divisome and work together to synthesize the septum is not well understood. In this review, we summarize the latest findings on divisome assembly and activation as well as provide our perspective on how these two processes might be regulated. This article is protected by copyright. All rights reserved.
April 17, 2017: Molecular Microbiology
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