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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of a Streptomyces coelicolor A3(2) locus containing the nucleoside diphosphate kinase (ndk) and folylpolyglutamate synthetase (folC) genes (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 159 (1998), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A 3.6-kb DNA fragment from Streptomyces coelicolor A3(2) with the genes valS probably encoding a valyl-tRNA synthetase, folC encoding folylpolyglutamate synthetase, and ndk encoding a nucleoside diphosphate kinase was analysed. folC and ndk are separated by a small open reading frame of unknown function, orfX. The deduced folC gene product is a protein of 46 677 Da whose sequence is similar to other folylpolyglutamate synthetases and folylpolyglutamate synthetase-dihydrofolate synthetases from both Gram-positive and Gram-negative bacteria. After cloning folC behind the lacZ promoter, the Streptomyces folC complemented a folC mutant of Escherichia coli. An essential function for Streptomyces folC was suggested by the fact that it could not be mutated using a conventional gene disruption technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1998.tb12873.x
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  • 2
    Electronic Resource
    Electronic Resource
    Stress-activated expression of a Streptomyces pristinaespiralis multidrug resistance gene (ptr) in various Streptomyces spp. and Escherichia coli (1995)
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Scientific Publication
    Molecular microbiology 17 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A promoter which controls expression of the pristinamycin multidrug resistance gene (ptr) in Streptomyces pristinaspiralis could be induced by physiological stresses in both Streptomyces spp. and Escherichia coli. In S. pristinaspiralis, the ptr promoter (Pptr) was induced by pristinamycin I (PI) or pristinamycin II (PII). Streptomyces lividans was adopted as a convenient heterologous host for studies of Pptr regulation since it has no known pristinamycin biosynthetic genes. Two key regulatory features were documented in these studies: many (19 of 70) antibiotics and chemicals with no common targets or structural features induced the Pptr; induction with PI was most efficient during a transition phase when antibiotic biosynthetic genes are switched on. In Streptomyces coelicolor, Pptr activity was similarly inducible by PI and not dependent on sigma factors HrdA, HrdC, or HrdD. In E. coli, Pptr cloned in the bifunctional promoter probe vector plJ2839 was functional and activated upon entry into stationary phase in the absence of exogenous inducer. Finally, gel-retardation studies demonstrated a Pptr-binding protein in S. lividans (where its activity was PI-inducible), S. coelicolor and S. pristinaespiralis. The fact that this activity was not detected in E. coli suggested the existence of another regulatory system perhaps also present in Streptomyces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.mmi_17051001.x
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  • 3
    Electronic Resource
    Electronic Resource
    Developmental control of the heat-shock stress regulon in Streptomyces coelicolor (1995)
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Scientific Publication
    Molecular microbiology 17 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In the differentiating eubacterium Streptomyces coelicolor, nutritional imbalances activate a developmental programme which involves the heat-shock stress regulon. In liquid batch cultures, the growth curve could be separated into four components: rapid growth 1 (RG1), transition (T), rapid growth 2 (RG2) and stationary (S). Patterns of gene expression in cultures subjected to heat shock in various phases were recorded on two-dimensional gels and analysed using advanced statistical methods. The responses of all heat-shock proteins (HSPs) were highly dependent upon the growth phase, thus demonstrating that the four phases of growth were physiologically distinct. For many HSPs, the levels of thermal induction attained were closely related to growth stage-determined levels of synthesis before heat shock, thus supporting the idea that developmental and thermal induction of this stress regulon have common control elements. Cluster analysis identified five groups of HSPs displaying similar kinetics of heat and developmentally induced synthesis, probably reflecting the influence of major regulatory systems. Methods introduced here to analyse the response of groups of genes to multiple simultaneous stimuli should find broad applications to studies of other prokaryotic and eukaryotic regulons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.mmi_17040737.x
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  • 4
    Electronic Resource
    Electronic Resource
    Pleiotropic effects of cAMP on germination, antibiotic biosynthesis and morphological development in Streptomyces coelicolor (1998)
    Oxford BSL : Blackwell Science Ltd, UK
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In wild-type Streptomyces coelicolor MT1110 cultures, cyclic adenosine 3′,5′ monophosphate (cAMP) was synthesized throughout the developmental programme with peaks of accumulation both during germination and later when aerial mycelium and actinorhodin were being produced. Construction and characterization of an adenylate cyclase disruption mutant (BZ1) demonstrated that cAMP facilitated these developmental processes. Although pulse-labelling experiments showed that a similar germination process was initiated in BZ1 and MT1110, germ-tube emergence was severely delayed in BZ1 and never occurred in more than 85% of the spores. Studies of growth and development on solid glucose minimal medium (SMMS, buffered or unbuffered) showed that MT1110 and BZ1 produced acid during the first rapid growth phase, which generated substrate mycelium. Thereafter, on unbuffered SMMS, only MT1110 resumed growth and produced aerial mycelium by switching to an alternative metabolism that neutralized its medium, probably by reincorporating and metabolizing extracellular acids. BZ1 was not able to neutralize its medium or produce aerial mycelium on unbuffered SMMS; these defects were suppressed by high concentrations (〉1 mM) of cAMP during early growth or on buffered medium. Other developmental mutants (bldA, bldB, bldC, bldD, bldG) also irreversibly acidified this medium. However, these bald mutants were not suppressed by exogenous cAMP or neutralizing buffer. BZ1 also differentiated when it was cultured in close proximity to MT1110, a property observed in cross-feeding experiments between bald mutants and commonly thought to reflect diffusion of a discrete positively acting signalling molecule. In this case, MT1110 generated a more neutral pH environment that allowed BZ1 to reinitiate growth and form aerial mycelium. The fact that actinorhodin synthesis could be induced by concentrations of cAMP (〈 20 μM) found in the medium of MT1110 cultures, suggested that it may serve as a diffusible signalling molecule to co-ordinate antibiotic biosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01033.x
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  • 5
    Electronic Resource
    Electronic Resource
    Unusual regulatory mechanism for a Streptomyces multidrug resistance gene, ptr, involving three homologous protein-binding sites overlapping the promoter region (1995)
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Scientific Publications
    Molecular microbiology 17 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A promoter controlling expression of the pristinamycin multidrug resistance gene (ptr), originally isolated from Streptomyces pristinaespiralis, is inducible by many toxic compounds in various Streptomyces species. Studies of ptr promoter control were carried out in the heterologous host, Streptomyces lividans. In S. lividans, a regulatory protein or a protein complex (Pip), identified by its ability to bind to the ptr promoter in gel-retardation experiments, was induced by pristinamycin I (PI). In situ copper-phenanthroline foot-printing analysis identified three (A, B, and C) similar Pip-binding sites having the sequence GTACA(C/G)CGTA(C/T). These sites overlapped with functionally important regions of the promoter: the ‘A’ site overlapped with the −35 hexamer, ‘B’ overlapped with the −10 hexamer and ‘C’ was located between the transcription start site and the Shine—Dalgarno sequence. A GT—AG dinucleotide mutation was introduced at positions 8–9 of the consensus sequence to generate seven variant promoters: three mutated in one of the three sites, three mutated in two sites, and one mutated in all three sites. Whereas these promoters had reduced antibiotic (PI)-induced activity, their levels of expression in the absence of PI was higher. This suggested an unusual regulatory mechanism in which Pip could act either as an activator or repressor. Gel shift experiments revealed Pip or its homologues in many other Streptomyces species, suggesting that it is widely employed in the regulation of antibiotic resistance genes and perhaps secondary metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.mmi_17061109.x
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular characterization and transcriptional analysis of a multidrug resistance gene cloned from the pristinamycin-producing organism, Streptomyces pristinaespiralis (1995)
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Scientific Publication
    Molecular microbiology 17 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A multidrug resistance gene (mdr) has been cloned from Streptomyces pristinaespiralis, a producer of two antibiotics having synergistic activities together known as pristinamycin. This gene, ptr, provides resistance not only to two structurally dissimilar compounds (pristinamycin I, PI; pristinamycin II, PII) and the natural pristinamycin mixture but also to rifampicin. Mutagenesis and subcloning of ptr localized it to a 2 kb region which was sequenced and analysed. It contained an open reading frame of 1506 bp which encoded a putative membrane protein with 14 hydrophobic domains, and showed sequence similarity to a superfamily of bacterial proteins that employ transmembrane electrochemical gradients to catalyse active efflux of various antibiotics and toxic compounds. Ptr was most similar to a subfamily which included other mdr genes and antibiotic transport genes associated with antibiotic biosynthetic gene clusters in actinomycetes. In vitro coupled transcription-translation experiments were used to identify the ptr gene product. Analysis of the upstream region did not reveal a divergently transcribed repressor gene, as is the case for several related resistance determinants involved in antibiotic transport, suggesting that ptr is regulated by a different mechanism. Transcriptional analyses of this gene, carried out in both S. pristinaespiralis and Streptomyces lividans, indicated the same transcriptional start point and predicted −10 and −35 hexamers which were somewhat similar to Streptomyces vegetative-type promoters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.mmi_17050989.x
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  • 7
    Electronic Resource
    Electronic Resource
    Identification of procaryotic developmental stages by statistical analyses of two-dimensional gel patterns (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 1418-1428 
    Details
    ISSN: 0173-0835
    Keywords: Two-dimentional polyacrylamide gel electrophoresis ; Streptomyces ; Development ; Multivariate ; Regulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Multivariate statistical comparisons of two-dimensional protein (2-D) gel patterns were used for the first time to define stages of a biological developmental system. The differentiating procaryote, Streptomyces coelicolor, was radiolabeled in liquid cultures at 16 intervals during development, and radioactive proteins were separated and quantified on 2-D gels. Cluster, principal component, and correlation analyses classified these gel patterns into four distinct groups, each reflecting a pattern of gene expression specific for a stage of development. These studies focused our attention on a phase of arrested growth as a key regulatory transition leading to secondary metabolism and a phase of renewed growth. Proteins whose synthesis was switched on or off during the “transitional” phase (some 21 and 18, respectively) were identified and will be the focus of future studies designed to identify their physiological or regulatory function.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150180817
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