Microbiology (United Kingdom)
1350-0872
1465-2080
Anh Quốc
Cơ quản chủ quản: Microbiology Society , MICROBIOLOGY SOC
Lĩnh vực:
Microbiology
Phân tích ảnh hưởng
Thông tin về tạp chí
We publish high-quality original research on bacteria, fungi, protists, archaea, algae, parasites and other microscopic life forms. Topics include but are not limited to: Antimicrobials and antimicrobial resistance Bacteriology and parasitology Biochemistry and biophysics Biofilms and biological systems Biotechnology and bioremediation Cell biology and signalling Chemical biology Cross-disciplinary work Ecology and environmental microbiology Food microbiology Genetics Host–microbe interactions Microbial methods and techniques Microscopy and imaging Omics, including genomics, proteomics and metabolomics Physiology and metabolism Systems biology and synthetic biology The microbiome.
Các bài báo tiêu biểu
Genome of Methanoregula boonei 6A8 reveals adaptations to oligotrophic peatland environments
Tập 161 Số 8 - Trang 1572-1581 - 2015
Assembly of outer-membrane proteins in bacteria and mitochondria The cell envelope of Gram-negative bacteria consists of two membranes separated by the periplasm. In contrast with most integral membrane proteins, which span the membrane in the form of hydrophobicα -helices, integral outer-membrane proteins (OMPs) formβ -barrels. Similarβ -barrel proteins are found in the outer membranes of mitochondria and chloroplasts, probably reflecting the endosymbiont origin of these eukaryotic cell organelles. How theseβ -barrel proteins are assembled into the outer membrane has remained enigmatic for a long time. In recent years, much progress has been reached in this field by the identification of the components of the OMP assembly machinery. The central component of this machinery, called Omp85 or BamA, is an essential and highly conserved bacterial protein that recognizes a signature sequence at the C terminus of its substrate OMPs. A homologue of this protein is also found in mitochondria, where it is required for the assembly ofβ -barrel proteins into the outer membrane as well. Although accessory components of the machineries are different between bacteria and mitochondria, a mitochondrialβ -barrel OMP can be assembled into the bacterial outer membrane and, vice versa, bacterial OMPs expressed in yeast are assembled into the mitochondrial outer membrane. These observations indicate that the basic mechanism of OMP assembly is evolutionarily highly conserved.
Tập 156 Số 9 - Trang 2587-2596 - 2010
Alteration in cellular fatty acid composition as a response to salt, acid, oxidative and thermal stresses in Lactobacillus helveticus
Tập 147 Số 8 - Trang 2255-2264 - 2001
The MAP kinase signal transduction network in Candida albicans MAP (mitogen-activated protein) kinase-mediated pathways are key elements in sensing and transmitting the response of cells to environmental conditions by the sequential action of phosphorylation events. In the fungal pathogenCandida albicans , different routes have been identified by genetic analysis, and especially by the phenotypic characterization of mutants altered in the Mkc1, Cek1/2 and Hog1 MAP kinases. The cell integrity (orMKC1 -mediated) pathway is primarily involved in the biogenesis of the cell wall. The HOG pathway participates in the response to osmotic stress while the Cek1 pathway mediates mating and filamentation. Their actual functions are, however, much broader and Mkc1 senses several types of stress, while Hog1 is also responsive to other stress conditions and participates in two morphogenetic programmes: filamentation and chlamydospore formation. Furthermore, it has been recently shown that Cek1 participates in a putative pathway involved in the construction of the cell wall and which seems to be operative under basal conditions. As these stimuli are frequently encountered in the human host, they provide a reasonable explanation for the significant reduction in pathogenicity that several signal transduction mutants show in certain animal models of virulence. MAPK pathways therefore represent an attractive multienzymic system for which novel antifungal therapy could be designed.
Tập 152 Số 4 - Trang 905-912 - 2006
Antigenic variants in Bordetella pertussis strains isolated from vaccinated and unvaccinated children
Tập 145 Số 8 - Trang 2069-2075 - 1999
Differential expression of key pneumococcal virulence genes in vivo Few studies have examined in vivo virulence gene expression in Streptococcus pneumoniae . In this study, expression of key pneumococcal virulence genes cbpA , pspA , ply , psaA , cps2A , piaA , nanA and spxB in the nasopharynx, lungs and bloodstream of mice was investigated, following intranasal challenge with the serotype 2 strain D39. Bacterial RNA was extracted, linearly amplified and assayed by real-time RT-PCR. At 72 h, cbpA mRNA was present at higher levels in the nasopharynx and lungs than in the blood. At this time-point, the mRNAs for PspA and PiaA were most abundant in the nasopharynx, whereas no significant difference in gene expression between niches was observed for ply , psaA and cps2A . Both nanA and spxB mRNAs were present in higher amounts in the nasopharynx than in the lungs or blood. These findings illustrate the dynamic nature of pneumococcal virulence gene expression in vivo .
Tập 152 Số 2 - Trang 305-311 - 2006
Surface-associated lipoprotein PpmA of Streptococcus pneumoniae is involved in colonization in a strain-specific manner Streptococcus pneumoniae produces two surface-associated lipoproteins that share homology with two distinct families of peptidyl-prolyl isomerases (PPIases), the streptococcal lipoprotein rotamase A (SlrA) and the putative proteinase maturation protein A (PpmA). Previously, we have demonstrated that SlrA has PPIase activity, and that the enzyme plays a role in pneumococcal virulence. Here, we investigated the contribution of PpmA to pneumococcal pathogenesis. Pneumococcal mutants of D39 and TIGR4 lacking the gene encoding PpmA were less capable of persisting in the nasopharynx of mice, demonstrating the contribution of PpmA to pneumococcal colonization. This observation was partially confirmedin vitro , as the pneumococcal mutants NCTC10319ΔppmA and TIGR4Δcps ΔppmA , but not D39Δcps ΔppmA , were impaired in adherence to Detroit 562 pharyngeal cells. This suggests that the contribution of PpmA to pneumococcal colonization is not solely the result of its role in adherence to epithelial cells. Deficiency in PpmA did not result in reduced binding to various extracellular matrix and serum proteins. Similar to SlrA, we observed that PpmA was involved in immune evasion. Uptake of PpmA-deficient D39Δcps and NCTC10319 by human polymorphonuclear leukocytes was significantly enhanced compared to the isogenic wild-types. In addition, ingestion of D39ΔppmA , but not that of either NCTC10319ΔppmA or TIGR4ΔppmA , by murine macrophage cell line J774 was also enhanced, whereas intracellular killing remained unaffected. We conclude that PpmA contributes to the early stages of infection, i.e. colonization. The contribution of PpmA to virulence can be explained by its strain-specific role in adherence to epithelial cells and contribution to the evasion of phagocytosis.
Tập 155 Số 7 - Trang 2401-2410 - 2009
Maintenance of ΔpH by a butanol-tolerant mutant of Clostridium beijerinckii The isolation ofClostridium beijerinckii mutants that are more tolerant of butanol than the wild-type offered the opportunity to investigate whether the membrane activities which are required for maintaining the transmembrane ΔpH (the difference in pH between the cellular interior and exterior) are sensitive targets of butanol toxicity. The ΔpH was measured by the accumulation of [14 C]benzoate using late-exponential-phase cells which were suspended in citrate/phosphate buffer at pH 5 (to maximize the ΔpH component of the protonmotive force) and supplemented with glucose and Mg2+ . The ΔpH of the butanol-tolerant tolerant mutant, strain BR54, ofC. beijerinckii NCIMB 8052 was found to be significantly more tolerant of added butanol than the wild-type. Thus, in potassium citrate/phosphate buffer the mutant cells maintained a ΔpH of 1·4 when butanol was added to a concentration of 1·5 % (w/v), while the wild-type ΔpH was reduced to 0·1. The ΔpH of both strains was completely dissipated with 1·75 % butanol, an effect attributed to a chaotropic effect on the membrane phospholipids. Similar results were obtained in sodium citrate/phosphate buffer. In the absence of added Mg2+ , the ΔpH of the mutant decreased in both sodium and potassium citrate/phosphate buffer, but more rapidly in the former. Interestingly, the addition of butanol at low concentrations (0·8 %) prevented this ΔpH dissipation, but only in cells suspended in sodium citrate/phosphate buffer, and not in potassium citrate/phosphate buffer. In wild-type cells the decrease in ΔpH occurred more slowly than in the mutant, and sparing of the ΔpH by 0·8 % butanol was less pronounced. The authors interpret these data to mean that the ΔpH is dissipated in the absence of Mg2+ by a Na+ - or K+ -linked process, possibly by a Na+ /H+ or a K+ /H+ antiporter, and that the former is inhibited by butanol. Apparently, butanol can selectively affect a membrane-associated function at concentrations lower than required for the complete dissipation of transmembrane ion gradients. Additionally, since the butanol-tolerant mutant BR54 is deficient in the ability to detoxify methylglyoxal (MG) and contains higher levels of MG than the wild-type, the higher Na+ /H+ antiporter activity of the mutant may be due to the greater degree of protein glycation by MG in the mutant cells. The mechanism of butanol tolerance may be an indirect result of the elevated glycation of cell proteins in the mutant strain. Analysis of membrane protein fractions revealed that mutant cells contained significantly lower levels of unmodified arginine residues than those of the wild-type cells, and that unmodified arginine residues of the wild-type were decreased by exposure of the growing cells to added MG.
Tập 151 Số 2 - Trang 607-613 - 2005