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Shuanghong Xue, Emanuele G Biondi
The symbiotic nitrogen fixing species Sinorhizobium meliloti represents a remarkable model system for the class Alphaproteobacteria, which includes genera such as Caulobacter, Agrobacterium and Brucella. It is capable of living free in the soil, and is also able to establish a complex symbiosis with leguminous plants, during which its cell cycle program is completely rewired presumably due, at least in part, to the action of peptides secreted by the plant. Here we will discuss how the cell cycle regulation works in S...
May 18, 2018: Biochimica et Biophysica Acta
Ngoc Tuan Tran, Jing Zhang, Fan Xiong, Gui-Tang Wang, Wen-Xiang Li, Shan-Gong Wu
Gut microbiota plays a crucial importance in their host. Disturbance of the microbial structure and function is known to be associated with inflammatory intestinal disorders. Enteritis is a significant cause of high mortality in fish species, including grass carp (Ctenopharyngodon idellus). Study regarding the association between microbial alternations and enteritis in grass carp is still absent. In this study, changes in the gut microbiota of grass carp suffering from enteritis were investigated using NGS-based 16S rRNA sequencing...
May 18, 2018: World Journal of Microbiology & Biotechnology
Katy Poncin, Sébastien Gillet, Xavier De Bolle
The α-proteobacteria are a fascinating group of free-living, symbiotic and pathogenic organisms, including the Brucella genus, which is responsible for a worldwide zoonosis. One common feature of α-proteobacteria is the presence of a conserved response regulator called CtrA, first described in the model bacterium Caulobacter crescentus, where it controls gene expression at different stages of the cell cycle. Here, we focus on Brucella abortus and other intracellular α-proteobacteria in order to better assess the potential role of CtrA in the infectious context...
May 3, 2018: FEMS Microbiology Reviews
Justine Collier
Caulobacter crescentus is a free-living Alphaproteobacterium that thrives in oligotrophic environments. This review focuses on the regulatory network used by this bacterium to control the levels of cell division proteins, their organization inside the cell and their activity as a function of the cell cycle. Strikingly, C. crescentus makes frequent use of master transcriptional regulators and epigenetic signals, most likely to synchronize cell division with other events of the cell cycle. In addition, cellular metabolism and DNA damage sensors emerge as central players regulating cell division in response to changing environmental conditions...
April 28, 2018: Biochimica et Biophysica Acta
A B Westbye, L Kater, C Wiesmann, H Ding, C K Yip, J T Beatty
Several members of the Rhodobacterales ( Alphaproteobacteria ) produce a conserved horizontal gene transfer vector, called gene transfer agent (GTA), that appears to have evolved from a bacteriophage. The model system to study GTA biology is the R. capsulatus GTA (RcGTA), a small, tailed bacteriophage-like particle produced by a subset of the cells in a culture. The response regulator CtrA is conserved in the Alphaproteobacteria and is an essential regulator of RcGTA production: it controls production and maturation of the RcGTA particle and RcGTA release from cells...
April 6, 2018: Applied and Environmental Microbiology
Abhishek Jain, Wei Ning Chen
Nickel (Ni(II)) toxicity is addressed by many different bacteria, but bacterial responses to nickel stress are still unclear. Therefore, we studied the effect of Ni(II) toxicity on cell proliferation of α-proteobacterium Caulobacter crescentus. Next, we showed the mechanism that allows C. crescentus to survive in Ni(II) stress condition. Our results revealed that the growth of C. crescentus is severely affected when the bacterium was exposed to different Ni(II) concentrations, 0.003 mM slightly affected the growth, 0...
April 3, 2018: Applied Microbiology and Biotechnology
Camille A Bayas, Jiarui Wang, Marissa K Lee, Jared M Schrader, Lucy Shapiro, W E Moerner
We report the dynamic spatial organization of Caulobacter crescentus RNase E (RNA degradosome) and ribosomal protein L1 (ribosome) using 3D single-particle tracking and superresolution microscopy. RNase E formed clusters along the central axis of the cell, while weak clusters of ribosomal protein L1 were deployed throughout the cytoplasm. These results contrast with RNase E and ribosome distribution in Escherichia coli , where RNase E colocalizes with the cytoplasmic membrane and ribosomes accumulate in polar nucleoid-free zones...
April 2, 2018: Proceedings of the National Academy of Sciences of the United States of America
Min Liu, Yamei Ding, Mo Xian, Guang Zhao
BACKGROUND: Glycolate is a valuable chemical with extensive applications in many different fields. The traditional methods to synthesize glycolate are quite expensive and toxic. So, the biotechnological production of glycolate from sustainable feedstocks is of interest for its potential economic and environmental advantages. D-Xylose is the second most abundant sugar in nature and accounts for 18-30% of sugar in lignocellulose. New routes for the conversion of xylose to glycolate were explored...
March 28, 2018: Microbial Cell Factories
Bo-Young Hong, Joseph N Paulson, O Colin Stine, George M Weinstock, Jorge L Cervantes
The lung microbiota has received less attention compared to other body sites, in part because its study carries special technological difficulties related to obtaining reliable samples as compared to other body niches. The limited number of studies on the sputum microbiota on TB patients and controls available so far have reported inconsistent, and sometimes, contradictory results. Aiming to clarify if changes in the lung microbiota composition are associated with pulmonary TB, we performed a meta-analysis of available data on microbiota of the lower respiratory tract in TB patients and healthy controls...
March 2018: Tuberculosis
Matthew Tien, Aretha Fiebig, Sean Crosson
Cells adapt to shifts in their environment by remodeling transcription. Measuring changes in transcription at the genome scale is now routine, but defining the functional significance of individual genes within large gene expression datasets remains a major challenge. We applied a network-based algorithm to interrogate publicly available gene expression data to predict genes that serve major functional roles in Caulobacter crescentus stress survival. This approach identified GsrN, a conserved small RNA that is directly activated by the general stress sigma factor, σT , and functions as a potent post-transcriptional regulator of survival across distinct conditions including osmotic and oxidative stress...
March 14, 2018: ELife
Asli Yildirim, Michael Feig
High-resolution three-dimensional models of Caulobacter crescentus nucleoid structures were generated via a multi-scale modeling protocol. Models were built as a plectonemically supercoiled circular DNA and by incorporating chromosome conformation capture based data to generate an ensemble of base pair resolution models consistent with the experimental data. Significant structural variability was found with different degrees of bending and twisting but with overall similar topologies and shapes that are consistent with C...
May 4, 2018: Nucleic Acids Research
Xiaoxian Wu, Diane L Haakonsen, Allen G Sanderlin, Yue J Liu, Liqiang Shen, Ningning Zhuang, Michael T Laub, Yu Zhang
Canonical bacterial transcription activators bind to non-transcribed promoter elements to increase transcription of their target genes. Here we report crystal structures of binary complexes comprising domains of Caulobacter crescentus GcrA, a noncanonical bacterial transcription factor, that support a novel mechanism for transcription activation through the preferential binding of methylated cis-regulatory elements and the promotion of open complex formation through an interaction with region 2 of the principal σ factor, σ70...
April 6, 2018: Nucleic Acids Research
Lisa Wasserstrom, Diogo Portugal-Nunes, Henrik Almqvist, Anders G Sandström, Gunnar Lidén, Marie F Gorwa-Grauslund
Engineering of the yeast Saccharomyces cerevisiae towards efficient D-xylose assimilation has been a major focus over the last decades since D-xylose is the second most abundant sugar in nature, and its conversion into products could significantly improve process economy in biomass-based processes. Up to now, two different metabolic routes have been introduced via genetic engineering, consisting of either the isomerization or the oxido-reduction of D-xylose to D-xylulose that is further connected to the pentose phosphate pathway and glycolysis...
March 5, 2018: AMB Express
Ryosuke Ikebe, Yuri Kuwabara, Taiki Chikada, Hironori Niki, Daisuke Shiomi
Rod shape of bacterial cells such as Escherichia coli is mainly regulated by a supramolecular complex called elongasome including MreB actin. Deletion of the mreB gene in rod-shaped bacterium E. coli results in round-shaped cells. RodZ was isolated as a determinant of rod shape in E. coli, Caulobacter crescentus and Bacillus subtilis and it has been shown to be an interaction partner and a regulator of assembly of MreB through its cytoplasmic domain. As opposed to functions of the N-terminal cytoplasmic domain of RodZ, functions of the C-terminal periplasmic domain including a disordered region are still unclear...
April 2018: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Ashraf S A El-Sayed, Asma Akbar, Irum Iqrar, Robina Ali, David Norman, Mary Brennan, Gul Shad Ali
Biological control is an eco-friendly strategy for mitigating and controlling plant diseases with negligible effects on human health and environment. Biocontrol agents are mostly isolated from field crops, and microbiomes associated with wild native plants is underexplored. The main objective of this study was to characterize the bacterial isolates associated with Smilax bona-nox L, a successful wild plant with invasive growth habits. Forty morphologically distinct bacterial isolates were recovered from S. bona-nox...
March 2018: Microbiological Research
Luca Rossoni, Reuben Carr, Scott Baxter, Roxann Cortis, Thomas Thorpe, Graham Eastham, Gill Stephens
Bio-production of fuels and chemicals from lignocellulosic C5 sugars usually requires the use of the pentose phosphate pathway (PPP) to produce pyruvate. Unfortunately, the oxidation of pyruvate to acetyl-coenzyme A results in the loss of 33 % of the carbon as CO2, to the detriment of sustainability and process economics. To improve atom efficiency, we engineered Escherichia coli to utilize d-xylose constitutively using the Weimberg pathway, to allow direct production of 2-oxoglutarate without CO2 loss. After confirming enzyme expression in vitro, the pathway expression was optimized in vivo using a combinatorial approach, by screening a range of constitutive promoters whilst systematically varying the gene order...
March 2018: Microbiology
Christina Farr Zuend, John F Nomellini, John Smit, Marc S Horwitz
HSV-2 infection is a significant health problem and a major co-morbidity factor for HIV-1 acquisition, increasing risk of infection 2-4 fold. Condom based prevention strategies for HSV-2 and HIV-1 have not been effective at stopping the HIV-1 pandemic, indicating that alternative prevention strategies need to be investigated. We have previously developed an inexpensive HIV-1 specific microbicide that utilizes the S-layer mediated display capabilities of Caulobacter crescentus, and have shown that recombinant C...
February 12, 2018: Scientific Reports
Doreen Nguyen, Bert Ely
Bacteriophages remain an understudied component of bacterial communities. Therefore, our laboratory has initiated an effort to isolate large numbers of bacteriophages that infect Caulobacter crescentus to provide an estimate of the diversity of bacteriophages that infect this common environmental bacterium. The majority of the new isolates are phicbkviruses, a genus of giant viruses that appear to be Caulobacter specific. However, we have also isolated several Podoviruses with icosahedral heads and small tails...
June 2018: Current Microbiology
Rhudith B Cabulong, Won-Keun Lee, Angelo B Bañares, Kristine Rose M Ramos, Grace M Nisola, Kris Niño G Valdehuesa, Wook-Jin Chung
Glycolic acid (GA) is an ⍺-hydroxy acid used in cosmetics, packaging, and medical industries due to its excellent properties, especially in its polymeric form. In this study, Escherichia coli was engineered to produce GA from D-xylose by linking the Dahms pathway, the glyoxylate bypass, and the partial reverse glyoxylate pathway (RGP). Initially, a GA-producing strain was constructed by disrupting the xylAB and glcD genes in the E. coli genome and overexpressing the xdh(Cc) from Caulobacter crescentus. This strain was further improved through modular optimization of the Dahms pathway and the glyoxylate bypass...
March 2018: Applied Microbiology and Biotechnology
Michele Felletti, Deike J Omnus, Kristina Jonas
The decision to initiate DNA replication is a critical step in the cell cycle of all organisms. In nearly all bacteria, replication initiation requires the activity of the conserved replication initiation protein DnaA. Due to its central role in cell cycle progression, DnaA activity must be precisely regulated. This review summarizes the current state of DnaA regulation in the asymmetrically dividing α-proteobacterium Caulobacter crescentus, an important model for bacterial cell cycle studies. Mechanisms will be discussed that regulate DnaA activity and abundance under optimal conditions and in coordination with the asymmetric Caulobacter cell cycle...
January 31, 2018: Biochimica et Biophysica Acta
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