• 主题
高级搜索  >
历史搜索 清空历史

您现在的位置：首页>美国卫生研究院文献>Journal of Molecular Microbiology and Biotechnology

期刊信息

  • 期刊名称：

    -

  • 刊频： 8 no. a year, 2003-
  • NLM标题：
  • iso缩写： -
  • ISSN： -

年度选择

更多>>

  • 排序：
  • 显示：
  • 每页：
全选（0）
<1/2>
共35条结果
  • 1.

    【2hr】Comparative Analyses of Transport Proteins Encoded within the Genomes of Bdellovibrio bacteriovorus HD100 and Bdellovibrio exovorus JSS

    包量

    机译 Bdellovibrio bacteriovorus HD100和Bdellovibrio exovorus JSS基因组内编码的转运蛋白的比较分析
    摘要：Bdellovibrio, δ-proteobacteria, including B. bacteriovorus (Bba) and B. exovorus (Bex), are obligate predators of other Gram-negative bacteria. While Bba grows in the periplasm of the prey cell, Bex grows externally. We have analyzed and compared the transport proteins of these 2 organisms based on the current contents of the Transporter Classification Database (TCDB; ). Bba has 103 transporters more than Bex, 50% more secondary carriers, and 3 times as many MFS carriers. Bba has far more metabolite transporters than Bex as expected from its larger genome, but there are 2 times more carbohydrate uptake and drug efflux systems, and 3 times more lipid transporters. Bba also has polyamine and carboxylate transporters lacking in Bex. Bba has more than twice as many members of the Mot-Exb family of energizers, but both may have energizers for gliding motility. They use entirely different types of systems for iron acquisition. Both contain unexpectedly large numbers of pseudogenes and incomplete systems, suggesting that they are undergoing genome size reduction. Interestingly, all 5 outermembrane receptors in Bba are lacking in Bex. The 2 organisms have similar numbers and types of peptide and amino acid uptake systems as well as protein and carbohydrate secretion systems. The differences observed correlate with and may account, in part, for the different lifestyles of these 2 bacterial predators.
  • 2.

    【2hr】The Membrane Attack Complex/Perforin (MACPF) Superfamily

    包量

    机译 膜攻击复合物/穿孔素（MACPF）超家族
    摘要：The Membrane Attack Complex/Perforin (MACPF) superfamily consists of a diverse group of proteins involved in bacterial pathogenesis and sporulation as well as eukaryotic immunity, embryonic development, neural migration and fruiting body formation. The present work shows that the evolutionary relationships between the members of the superfamily, previously suggested by comparison of their tertiary structures, can also be supported by analyses of their primary structures. The superfamily includes the MACPF family (TC 1.C.39), the Cholesterol-dependent Cytolysin (CDC) family (TC 1.C.12.1 and 1.C.12.2) and the Pleurotolysin Pore-forming (Pleurotolysin B) family (TC 1.C.97.1), as revealed by expansion of each family by comparison against a large protein database, and by the comparisons of their Hidden Markov Models. Clustering analyses demonstrated grouping of the CDC homologues separately from the twelve MACPF subfamilies, which also grouped separately from the Pleurotolysin B family. Members of the MACPF superfamily revealed a remarkably diverse range of proteins spanning eukaryotic, bacterial and archaeal taxonomic domains, with notable variations in protein domain architectures. Our strategy should also be helpful in putting together other highly divergent protein families.
  • 3.

    【2hr】Synthetic, switchable enzymes

    包量

    机译 合成，可转换酶
    摘要：The construction of switchable, radiation-controlled, aptameric enzymes alias swenzymes is, in principle, feasible. We propose a strategy to make such catalysts from two (or more) aptamers each selected to bind specifically to one of the substrates in, for example, a two-substrate reaction. Construction of a combinatorial library of candidate swenzymes entails selecting a set of a million aptamers that bind one substrate and a second set of a million aptamers that bind the second substrate; the aptamers in these sets are then linked pairwise by a linker so bringing together the substrates. In the presence of the substrates, some linked aptamer pairs catalyze the reaction when exposed to external energy in the form of a specific frequency of low intensity, non-ionizing electromagnetic or acoustic radiation. Such swenzymes are detected via a separate, product-capturing, aptamer that changes conformation on capturing the product; this altered conformation allows it (1) to bind to every potential swenzyme in its vicinity (thereby giving a higher probability of capture to the swenzymes that generate the product) and (2) to bind to a sequence on a magnetic bead (thereby permitting purification of the swenzyme plus product-capturing aptamer by precipitation). Attempts to implement the swenzyme strategy may help elucidate fundamental problems in enzyme catalysis.
  • 4.

    【2hr】Science, Innovation and the Future of Humanity

    包量

    机译 科学，创新与人类的未来
    摘要：
  • 5.

    【2hr】Analysis of 58 families of Holins Using A Novel Program, PhyST

    包量

    机译 使用新型程序PhyST分析58个霍林家族
    摘要：We have designed a freely accessible program, PhyST, that allows the automated characterization of any family of homologous proteins within the Transporter Classification Database (TCDB). The program performs an NCBI-PSI-BLAST search and reports (1) the average protein sequence length ± standard deviations (SD), (2) average predicted number of transmembrane segments (TMSs), (3) total number of homologues retrieved, (4) a quantitative list of all source phyla and (5) potential fusion proteins of sizes considerably exceeding the average size of the proteins retrieved. We have applied this program to 58 families of holins, and the results are presented. The results show that holins are very rarely fused to other protein domains, suggesting that holins form transmembrane pores as homoooligomers without the participation of other proteins or protein domains.
  • 6.

    【2hr】Control of Transposon-mediated Directed Mutation by the Escherichia coli Phosphoenolpyruvate:Sugar Phosphotransferase System

    包量

    机译 大肠杆菌磷酸烯醇丙酮酸：糖磷酸转移酶系统控制转座子介导的定向突变
    摘要：The phosphoenolpyruvate:sugar phosphotransferase system (PTS) has been shown to control transport, cell metabolism and gene expression. We here present results supporting the novel suggestion that in certain instances, it also regulates mutation rate. Directed mutations are defined as mutations that occur at higher frequencies when beneficial than when neutral or detrimental. To date, the occurrence of directed point mutations has not been documented and confirmed, but a few examples of transposon-mediated directed mutation have been reported. Here we focus on the first and best-studied example of directed mutation, which involves the regulation of Insertion Sequence-5 (IS5) hopping into a specific site upstream of the glpFK glycerol utilization operon in Escherichia coli. This insertional event specifically activates expression of the glpFK operon, allowing growth of wild type cells with glycerol as a carbon source in the presence of non-metabolizable glucose analogues which normally block glycerol utilization. The sugar transporting PTS controls this process by regulating levels of cytoplasmic glycerol-3-phosphate and cyclic AMP as established in previous publications. Direct involvement of the glycerol repressor, GlpR, and the cyclic AMP receptor protein, Crp, in the regulation of transposon-mediated directed mutation has been demonstrated.
  • 7.

    【2hr】The Bacterial Phosphotransferase System: New frontiers 50 years after its discovery

    包量

    机译 细菌磷酸转移酶系统：发现后50年的新领域
    • 作者：Milton H. Saier, Jr
    • 刊名：Journal of Molecular Microbiology and Biotechnology
    • 2015年第0期
    摘要：
  • 8.

    【2hr】Topological Predictions for Integral Membrane Channel and CarrierProteins

    包量

    机译 整体膜通道和载体的拓扑预测蛋白质类
    摘要：We evaluated topological predictions for nine different programs, HMMTOP, TMHMM, SVMTOP, DAS, SOSUI, TOPCONS, PHOBIUS, MEMSAT-SVM (hereinafter referred to as MEMSAT), and SPOCTOPUS. These programs were first evaluated using four large topologically well-defined families of secondary transporters, and the three best programs were further evaluated using topologically more diverse families of channels and carriers. In the initial studies, the order of accuracy was: SPOCTOPUS>MEMSAT>HMMTOP>TOPCONS>PHOBIUS>TMHMM>SVMTOP>DAS>S OSUI. Some families, such as the Sugar Porter family (2.A.1.1) of the Major Facilitator Superfamily (MFS; TC# 2.A.1) and the Amino acid/Polyamine/Organocation (APC) Family (TC# 2.A.3), were correctly predicted with high accuracy while others, such as the Mitochondrial Carrier (MC) (TC# 2.A.29) and the K+ transporter (Trk) families (TC# 2.A.38), were predicted with much lower accuracy. For small, topologically homogeneous families, SPOCTOPUS and MEMSAT were generally most reliable, while with large, more diverse superfamilies, HMMTOP often proved to have the greatest prediction accuracy. We next developed a novel program, TM-STATS, that tabulates HMMTOP, SPOCTOPUS or MEMSAT-based topologicalpredictions for any subdivision (class, subclass, superfamily, family,subfamily, or any combination of these) of the Transporter ClassificationDatabase (TCDB; ) and examined the following subclasses:α-type channel proteins (TC subclasses 1.A and 1.E), secretedporeforming toxins (TC subclass 1.C) and secondary carriers (subclass 2.A).Histograms 3 were generated for each of these subclasses, and the results wereanalyzed according to subclass, family and protein. The results provide anupdate of topological predictions for integral membrane transport proteins aswell as guides for the development of more reliable topological predictionprograms, taking family-specific characteristics into account.
  • 9.

    【2hr】Regulation of crp gene expression by the catabolite repressor/activator, Cra, in Escherichia coli

    包量

    机译 分解代谢阻遏物/激活物Cra对大肠杆菌中crp基因表达的调控
    摘要：Growth on several carbon sources is dependent on the catabolite repressor/activator (Cra) protein although a Cra consensus DNA binding site is not present in the control regions of the relevant catabolic operons. We show that Cra regulates growth by activating expression of the crp gene. It thereby mediates catabolite repression of catabolic operons by an indirect mechanism.
  • 10.

    【2hr】Archaeal Chromosome Biology

    包量

    机译 古细菌染色体生物学
    摘要：Knowledge of the chromosome biology of archaeal species has grown considerably in the last 15 years, since the publication of the first full archaeal genome sequences. A number of model organisms have been studied, revealing a striking variety of mechanisms and modes of genome duplication and segregation. While clear sequence relationships between archaeal and eukaryotic replication proteins are well known, some archaea also seem to possess organizational parameters for replication and segregation that reveal further striking parallels to eukaryotes.
  • 11.

    【2hr】MukBEF, a chromosomal organizer

    包量

    机译 MukBEF，染色体组织者
    摘要：Global folding of bacterial chromosome requires the activity of condensins. These highly conserved proteins are involved in various aspects of higher order chromatin dynamics in a diverse range of organisms. Two distinct superfamilies of condensins have been identified in bacteria. The SMC-ScpAB proteins bear significant homology to eukaryotic condensins and cohesins and are found in most of presently sequenced bacteria. This review focuses on the MukBEF/MksBEF superfamily, which is broadly distributed across diverse bacteria and is characterized by low sequence conservation. The prototypical member of this superfamily, the Escherichia coli condensin MukBEF, continues to provide critical insights into the mechanism of the proteins. MukBEF acts as a complex molecular machine that assists in chromosome segregation and global organization. The review focuses on mechanistic analysis of DNA organization by MukBEF with the emphasis on its involvement in formation of chromatin scaffold and plausible other roles in chromosome segregation.
  • 12.

    【2hr】Chromosome Segregation in Vibrio cholerae

    包量

    机译 霍乱弧菌的染色体分离
    摘要：The study of chromosome segregation is currently one of the most exciting research frontiers in cell biology. In this review, we discuss our current knowledge of the chromosome segregation process in Vibrio cholerae, based primarily on findings from fluorescence microscopy experiments. This bacterium is of special interest because of its eukaryotic feature of having a divided genome, a feature shared with 10% of known bacteria. We also discuss how the segregation mechanisms of V. cholerae compare with those in other bacteria, and highlight some of the remaining questions regarding the process of bacterial chromosome segregation.
  • 13.

    【2hr】Major Facilitator Superfamily (MFS) Porters, LacY, FucP and XylE of Escherichia coli Appear to have Evolved Positionally Dissimilar Catalytic Residues without Rearrangement of 3-TMS Repeat Units

    包量

    机译 大肠杆菌的主要促进者超家族（MFS）搬运工，LacY，FucP和XylE似乎在不重新配置3-TMS重复单元的情况下发展了位置相异的催化残基
    摘要：Based on alleged functional residue correspondences between FucP and LacY, a recent study has resulted in a proposed model of 3-TMS unit rearrangements []. We rebut this theory, using seven different lines of evidence. Our observations suggest that these two transporters are homologous throughout their lengths, having evolved from a common ancestor without repeat unit rearrangements. We exploit the availability of the high resolution XylE crystal structures in multiple conformations including the inward facing state to render possible direct comparisons with LacY. Based on a Δdistance map, we confirm the conclusion of that the N-terminal 6 TMS halves of these transporters are internally less mobile than the second halves during the conformational transition from the outward occluded state to the inward occluded state and inward occluded state to inward open state. These observations, together with those of , lead to the suggestion that functionally equivalent catalytic residues involved in substrate binding and transport catalysis have evolved in dissimilar positions, but apparently often in similar positions in the putative 3-TMS repeat units, from a single structural scaffold without intragenic rearrangement.
  • 14.

    【2hr】Gas vesicles across kingdoms: a comparative solid state NMR study

    包量

    机译 跨王国的气体囊泡：固态NMR对比研究
    摘要：The buoyancy organelles of aquatic microorganisms have to meet stringent specifications: allowing gases to equilibrate freely across the proteinaceous shell, preventing the condensation of water vapor inside the hollow cavity, and resisting collapse under hydrostatic pressures that vary with column depth. These properties are provided by the 7–8 kDa gas vesicle protein A (GvpA), repeats of which form all but small, specialized portions of the shell. Magic angle spinning NMR is uniquely capable of providing high resolution information on the fold and assembly of GvpA. Here we compare results for the gas vesicles of the haloarchae Halobacterium salinarum with those obtained previously for the cyanobacterium Anabaena flos-aquae. The data suggest that the two organisms follow similar strategies for avoiding water condensation. On the other hand, in its relatively shallow habitat, H. salinarum is able to avoid collapse with a less costly GvpA fold than is adopted by A. flos-aquae.
  • 15.

    【2hr】Microcompartments and Protein Machines in Prokaryotes

    包量

    机译 原核生物中的微区室和蛋白质机器
    • 作者：Milton H. Saier, Jr.
    • 刊名：Journal of Molecular Microbiology and Biotechnology
    • 2013年第0期
    摘要：The prokaryotic cell was once thought of as a “bag of enzymes” with little or no intracellular compartmentalization. In this view, most reactions essential for life occurred as a consequence of random molecular collisions involving substrates, cofactors and cytoplasmic enzymes. Our current conception of a prokaryote is far from this view. We now consider a bacterium or an archaeon as a highly structured, non-random collection of functional membrane-embedded and proteinaceous molecular machines, each of which serves a specialized function. In this article we shall present an overview of such microcompartments including (i) the bacterial cytoskeleton and the apparati allowing DNA segregation during cells division, (ii) energy transduction apparati involving light-driven proton pumping and ion gradient-driven ATP synthesis, (iii) prokaryotic motility and taxis machines that mediate cell movements in response to gradients of chemicals and physical forces, (iv) machines of protein folding, secretion and degradation, (v) metabolasomes carrying out specific chemical reactions, (vi) 24 hour clocks allowing bacteria to coordinate their metabolic activities with the daily solar cycle and (vii) proteinaceous membrane compartmentalized structures such as sulfur granules and gas vacuoles. Membrane-bounded prokaryotic organelles were considered in a recent JMMB written symposium concerned with membraneous compartmentalization in bacteria []. By contrast, in this symposium, we focus on proteinaceous microcompartments. These two symposia, taken together, provide the interested reader with an objective view of the remarkable complexity of what was once thought of as a simple non-compartmentalized cell.
  • 16.

    【2hr】Functional Advantages Conferred by Extracellular Prokaryotic Membrane Vesicles

    包量

    机译 细胞外原核膜囊泡赋予的功能优势
    摘要：The absence of subcellular organelles is a characteristic typically used to distinguish prokaryotic from eukaryotic cells. But recent discoveries do not support this dogma. Over the past 50 years, researchers have begun to appreciate and characterize Gram-negative bacterial outer membrane derived vesicles and Gram-positive and archaeal membrane vesicles. These extracellular, membrane-bound organelles can perform a variety of functions, including binding and delivery of DNA, transport of virulence factors, protection of the cell from outer membrane targeting antimicrobials, and ridding the cell of toxic envelope proteins. Here we review the contributions of these extracellular organelles to prokaryotic physiology and compare these with the contributions of the bacterial interior membrane bound organelles responsible for harvesting light energy and for generating magnetic crystals of heavy metals. Understanding the roles of these multifunctional extracellular vesicle organelles as microbial tools will help us to better realize the diverse interactions that occur in our polymicrobial world.
  • 17.

    【2hr】Simple Method to Differentiate among Rickettsia Species

    包量

    机译 区分立克次体种的简单方法
    摘要：In this work we present a new option to identify 11 rickettsial species that cause human rickettsioses, with some advantages over the previous methods described. Using rickettsial isolates from 11 Rickettsia species as a sample, we used the polymerase chain reaction to amplify a 990- to 1,000-bp DNA fragment from the ompB gene, common for the 11 Rickettsia species analyzed in this study, which were digested with AluI restriction enzyme to obtain different digestion patterns. This restriction pattern can be visualized using a polyacrylamide gel electrophoresis technique. Using this method we could differentiate between the 11 Rickettsia species analyzed regardless of the group to which the Rickettsia belonged. We developed a simple method to identify 11 Rickettsia species which cause human rickettsioses using polymerase chain reaction and restriction fragment length polymorphism techniques with the advantage that it only needs one amplicon and only one restriction enzyme to obtain the restriction pattern. The identification of the species infecting vectors, reservoirs, and humans is essential to establish the ecological and behavioral ecosystem involved in its maintenance and transmission in nature in the specific region where the pathogen is circulating. This method is very helpful to identify Rickettsia species in a short time.
  • 18.

    【2hr】The Shells of BMC-Type Microcompartment Organelles in Bacteria

    包量

    机译 细菌中BMC型微室细胞器的外壳
    摘要：Bacterial microcompartments are large proteinaceous structures that act as metabolic organelles in many bacterial cells. A shell or capsid, which is composed of a few thousand protein subunits, surrounds a series of sequentially acting enzymes and controls the diffusion of substrates and products into and out of the interior. The carboxysome and the propanediol utilization microcompartment represent two well-studied systems among seven or more distinct types that can be delineated presently. Recent structural studies have highlighted a number of sophisticated mechanisms that underlie the function of bacterial microcompartment shell proteins. This review updates our understanding of bacterial microcompartment shells, how they are assembled, and how they carry out their functions in molecular transport and enzyme organization.
  • 19.

    【2hr】Prokaryotic Proteasomes: Nanocompartments of Degradation

    包量

    机译 原核蛋白酶体：降解的纳米隔室。
    摘要：Proteasomes are self-compartmentalized energy-dependent proteolytic machines found in Archaea, Actinobacteria species of bacteria and eukaryotes. Proteasomes consist of two separate protein complexes, the core particle that hydrolyzes peptide bonds and an AAA+ ATPase domain responsible for the binding, unfolding and translocation of protein substrates into the core particle for degradation. Similarly to eukaryotes, proteasomes play a central role in protein degradation and can be essential in Archaea. Core particles associate with and utilize a variety of ATPase complexes to carry out protein degradation in Archaea. In actinobacterial species, such as Mycobacterium tuberculosis, proteasome-mediated degradation is associated with pathogenesis and does not appear to be essential. Interestingly, both actinobacterial species and Archaea use small proteins to covalently modify proteins, prokaryotic ubiquitin-like proteins (Pup) in Actinobacteria and ubiquitin-like small archaeal modifier proteins (SAMP) in Archaea. These modifications may play a role in proteasome targeting similar to the ubiquitin-proteasome system in eukaryotes.
  • 20.

    【2hr】Staphylococcus aureus persisters tolerant to bactericidal antibiotics

    包量

    机译 金黄色葡萄球菌对杀菌抗生素具有耐受力
    摘要：Bacterial persister cells are non- or slow growing reversible phenotypic variants of the wild type, tolerant to bactericidal antibiotics. We here analyzed Staphylococcus aureus persister levels by monitoring colony forming unit (CFU) counts of planktonically grown cells treated with six different antimicrobials over time. Model laboratory strains HG001-HG003, SA113 and small colony variant (SCV) strains hemB and menD were challenged by the compounds at different logs of minimal inhibitory concentration (MIC) in exponential or stationary growth phase. Antibiotic tolerance was usually elevated in SCV strains compared to normally growing cells and in stationary vs. exponential phase cultures. Biphasic killing kinetics, typical for persister cell enrichment, were observed in both growth phases under different selective conditions. Treatment of exponential phase cultures of HG001-HG003 with 10-fold MIC of tobramycin resulted in the isolation of persisters which upon cultivation on plates formed either normal or phenotypically stable small colonies. Trajectories of different killing curves indicated physiological heterogeneity within persister subpopulations. Daptomycin added at 100-fold MIC to stationary phase SA113 cells rapidly isolated very robust persisters. Fractions of antibiotic tolerant cells were observed with all S. aureus strains and mutants tested. Our results refute the hypothesis that S. aureus stationary phase cells are equivalent to persisters, as not all of these cells showed antibiotic tolerance. Isolation of S. aureus persisters of different robustness seems to dependent on the kind and concentration of the antibiotic, as well as on the strain used.
题名 作者 来源 发表时间

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号