共查询到20条相似文献,搜索用时 31 毫秒
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Lu Li Jiawen Zhu Kui Yang Zhuofei Xu Ziduo Liu Rui Zhou 《Journal of microbiology (Seoul, Korea)》2014,52(6):473-481
Actinobacillus pleuropneumoniae is an important porcine respiratory pathogen causing great economic losses in the pig industry worldwide. Oxygen deprivation is a stress that A. pleuropneumoniae will encounter during both early infection and the later, persistent stage. To understand modulation of A. pleuropneumoniae gene expression in response to the stress caused by anaerobic conditions, gene expression profiles under anaerobic and aerobic conditions were compared in this study. The microarray results showed that 631 genes (27.7% of the total ORFs) were differentially expressed in anaerobic conditions. Many genes encoding proteins involved in glycolysis, carbon source uptake systems, pyruvate metabolism, fermentation and the electron respiration transport chain were up-regulated. These changes led to an increased amount of pyruvate, lactate, ethanol and acetate in the bacterial cells as confirmed by metabolite detection. Genes encoding proteins involved in cell surface structures, especially biofilm formation, peptidoglycan biosynthesis and lipopolysaccharide biosynthesis were up-regulated as well. Biofilm formation was significantly enhanced under anaerobic conditions. These results indicate that induction of central metabolism is important for basic survival of A. pleuropneumoniae after a shift to an anaerobic environment. Enhanced biofilm formation may contribute to the persistence of this pathogen in the damaged anaerobic host tissue and also in the early colonization stage. These discoveries give new insights into adaptation mechanisms of A. pleuropneumoniae in response to environmental stress. 相似文献
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Bokyung Son Jennifer Patterson-West Melissa Arroyo-Mendoza Revathy Ramachandran James
R Iben Jingen Zhu Venigalla Rao Emilios
K Dimitriadis Deborah
M Hinton 《Nucleic acids research》2021,49(16):9229
Nucleoid Associated Proteins (NAPs) organize the bacterial chromosome within the nucleoid. The interaction of the NAP H-NS with DNA also represses specific host and xenogeneic genes. Previously, we showed that the bacteriophage T4 early protein MotB binds to DNA, co-purifies with H-NS/DNA, and improves phage fitness. Here we demonstrate using atomic force microscopy that MotB compacts the DNA with multiple MotB proteins at the center of the complex. These complexes differ from those observed with H-NS and other NAPs, but resemble those formed by the NAP-like proteins CbpA/Dps and yeast condensin. Fluorescent microscopy indicates that expression of motB in vivo, at levels like that during T4 infection, yields a significantly compacted nucleoid containing MotB and H-NS. motB overexpression dysregulates hundreds of host genes; ∼70% are within the hns regulon. In infected cells overexpressing motB, 33 T4 late genes are expressed early, and the T4 early gene repEB, involved in replication initiation, is up ∼5-fold. We postulate that MotB represents a phage-encoded NAP that aids infection in a previously unrecognized way. We speculate that MotB-induced compaction may generate more room for T4 replication/assembly and/or leads to beneficial global changes in host gene expression, including derepression of much of the hns regulon. 相似文献
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Horizontal DNA transfer plays a major role in the evolution of bacteria. It allows them to acquire new traits rapidly and these may confer fitness advantages as the bacteria compete with others in the environment. Historically, the mechanisms of horizontal DNA transfer, chiefly conjugation, transformation and transduction, have received a great deal of attention. Less attention has been focused on the regulatory problems that may accompany the acquisition of new genes by lateral routes. How are these genes integrated into the existing regulatory circuits of the cell? Does a process of 'plug-and-play' operate, or are the new genes silenced pending the evolution of regulatory mechanisms that make their expression not only safe but also beneficial to both the gene and its new host? Recent research shows that bacterial nucleoid-associated proteins such as H-NS, HU and Fis are important contributors to the processes of regulatory integration that accompany horizontal gene transfer. A key emerging theme is the antagonism that exists between the DNA–protein–DNA bridging activity of the H-NS repressor and the DNA-bending and DNA-wrapping activities of regulatory proteins that oppose H-NS. 相似文献
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The classic expression pattern of the Fis global regulatory protein during batch culture consists of a high peak in the early logarithmic phase of growth, followed by a sharp decrease through mid-exponential growth phase until Fis is almost undetectable at the end of the exponential phase. We discovered that this pattern is contingent on the growth regime. In Salmonella enterica serovar Typhimurium cultures grown in non-aerated SPI1-inducing conditions, Fis can be detected readily in stationary phase. On the other hand, cultures grown with standard aeration showed the classic Fis expression pattern. Sustained Fis expression in non-aerated cultures was also detected in some Escherichia coli strains, but not in others. This novel pattern of Fis expression was independent of sequence differences in the fis promoter regions of Salmonella and E. coli. Instead, a clear negative correlation between the expression of the Fis protein and of the stress-and-stationary-phase sigma factor RpoS was observed in a variety of strains. An rpoS mutant displayed elevated levels of Fis and had a higher frequency of epithelial cell invasion under these growth conditions. We discuss a model whereby Fis and RpoS levels vary in response to environmental signals allowing the expression and repression of SPI1 invasion genes. 相似文献
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Xanthomonas axonopodis pv. citri (Xac) causes citrus canker disease, a major threat to citrus production worldwide. Accumulating evidence suggests that the formation of biofilms on citrus leaves plays an important role in the epiphytic survival of this pathogen prior to the development of canker disease. However, the process of Xac biofilm formation is poorly understood. Here, we report a genome-scale study of Xac biofilm formation in which we identified 92 genes, including 33 novel genes involved in biofilm formation and 7 previously characterized genes, colR, fhaB, fliC, galU, gumD, wxacO, and rbfC, known to be important for Xac biofilm formation. In addition, 52 other genes with defined or putative functions in biofilm formation were identified, even though they had not previously reported been to be associated with biofilm formation. The 92 genes were isolated from 292 biofilm-defective mutants following a screen of a transposon insertion library containing 22,000 Xac strain 306 mutants. Further analyses indicated that 16 of the novel genes are involved in the production of extracellular polysaccharide (EPS) and/or lipopolysaccharide (LPS), 7 genes are involved in signaling and regulatory pathways, and 5 genes have unknown roles in biofilm formation. Furthermore, two novel genes, XAC0482, encoding a haloacid dehalogenase-like phosphatase, and XAC0494 (designated as rbfS), encoding a two-component sensor protein, were confirmed to be biofilm-related genes through complementation assays. Our data demonstrate that the formation of mature biofilm requires EPS, LPS, both flagellum-dependent and flagellum-independent cell motility, secreted proteins and extracellular DNA. Additionally, multiple signaling pathways are involved in Xac biofilm formation. This work is the first report on a genome-wide scale of the genetic processes of biofilm formation in plant pathogenic bacteria. The report provides significant new information about the genetic determinants and regulatory mechanism of biofilm formation. 相似文献
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The developmental processes that give rise to the animal body plan are exceedingly complex. Model systems such as Drosophila melanogaster have yielded profound insight into roles of conserved genes and genetic pathways in development. Drosophila development begins with the formation of sperm and eggs, and proceeds through several morphologically distinct stages including development of the early embryo, larval instars, formation of pupae, and differentiation of adult tissues. The nuclear transport of proteins and RNAs represents a critical step in the regulation of gene expression during every stage of development and tissue differentiation. Studies of the nuclear transport machinery in Drosophila refute the notion that nuclear transport is strictly a housekeeping process without specific regulatory roles in development. Rather, they support the idea that the basal nuclear transport machinery has adapted during the evolution of the metazoan body plan to play important regulatory roles in key developmental events. 相似文献
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Fredj Ben Bdira Amanda M Erkelens Liang Qin Alexander N Volkov Andrew
M Lippa Nicholas Bowring Aimee
L Boyle Marcellus Ubbink Simon
L Dove Remus
T Dame 《Nucleic acids research》2021,49(18):10770
H-NS family proteins, bacterial xenogeneic silencers, play central roles in genome organization and in the regulation of foreign genes. It is thought that gene repression is directly dependent on the DNA binding modes of H-NS family proteins. These proteins form lateral protofilaments along DNA. Under specific environmental conditions they switch to bridging two DNA duplexes. This switching is a direct effect of environmental conditions on electrostatic interactions between the oppositely charged DNA binding and N-terminal domains of H-NS proteins. The Pseudomonas lytic phage LUZ24 encodes the protein gp4, which modulates the DNA binding and function of the H-NS family protein MvaT of Pseudomonas aeruginosa. However, the mechanism by which gp4 affects MvaT activity remains elusive. In this study, we show that gp4 specifically interferes with the formation and stability of the bridged MvaT–DNA complex. Structural investigations suggest that gp4 acts as an ‘electrostatic zipper’ between the oppositely charged domains of MvaT protomers, and stabilizes a structure resembling their ‘half-open’ conformation, resulting in relief of gene silencing and adverse effects on P. aeruginosa growth. The ability to control H-NS conformation and thereby its impact on global gene regulation and growth might open new avenues to fight Pseudomonas multidrug resistance. 相似文献
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系统评价糖尿病药物对乳杆菌属微生物生长的影响,并进一步探讨糖尿病药物促进乳杆菌属微生物生长的作用机制。
利用体外纯培养法评估糖尿病药物对乳杆菌属微生物生长的影响,筛选出具有促进作用的“药菌组合”,并进一步采用非靶向代谢组学技术检测“药菌组合”培养液上清中的代谢物组;采用结晶紫染色法和RT-qPCR法分别检测特定乳杆菌生物膜形成和细菌素生物合成基因的表达。
10种常见糖尿病药物对乳杆菌的生长主要表现为抑制作用,仅那格列奈可在低浓度下刺激嗜酸乳杆菌的生长,促进率达48.30%。“那格列奈―嗜酸乳杆菌组合”培养液上清中共注释到584种已知代谢物,其中差异代谢物有42个,主要富集在氨基酸代谢和生物合成、氨酰t-RNA生物合成和次生代谢产物生物合成等代谢通路上;同时,那格列奈还促进了嗜酸乳杆菌生物膜的形成以及增加了生物膜的黏附性,并上调细菌素合成结构基因的表达(
糖尿病药物对乳杆菌生长普遍具有抑制作用,但那格列奈可通过调节氨基酸代谢和生物合成、促进生物膜的分泌和细菌素的生物合成来刺激嗜酸乳杆菌的生长。
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