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  • 1
    Electronic Resource
    Electronic Resource
    Generation of a non-sporulating strain of Streptomyces coelicolor A3(2) by the manipulation of a developmentally controlled ftsZ promoter (2000)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 38 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The differentiation of Streptomyces aerial hyphae into chains of unigenomic spores occurs through the synchronous formation of multiple FtsZ rings, leading to sporulation septa. We show here that developmental control of ftsZ transcription is required for sporulation in Streptomyces coelicolor A3(2). Three putative ftsZ promoters were detected in the ftsQ–ftsZ intergenic region. In addition, some readthrough from upstream promoter(s) contributed to ftsZ transcription. S1 nuclease protection assays and transcriptional fusions of the ftsZ promoter region to the egfp gene (for green fluorescent protein) provided evidence that ftsZ2p is a developmentally controlled promoter that is specifically upregulated in sporulating aerial hyphae. This upregulation required all the six early regulatory sporulation genes that were tested: whiA, B, G, H, I and J. The DNA sequence of the promoter indicated that it is not part of the developmental regulon that is controlled by the RNA polymerase sigma factor σWhiG. A strain in which the ftsZ2p promoter was inactivated grew normally during vegetative growth and formed aerial mycelium, but was deficient in sporulation septation. Thus, ftsZ2p was dispensable for vegetative growth, but was required for the strain to make sufficient FtsZ to support developmentally controlled multiple cell divisions in aerial hyphae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.02177.x
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  • 2
    Electronic Resource
    Electronic Resource
    Bacterial transcription factors involved in global regulation[We dedicat] (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 33 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The presence of intricate global cell regulation mechanisms may be one reason for the exceptional environmental and evolutionary success of microbes. Promoters, the cis-acting signals, are responsive to several stimuli related to growth, stress and substrate specificity. Their response is mediated by a wide variety of trans-acting regulators that sense the environment and the physiological state of the cell and adjust the transcription of specific genes. One of the main transcriptional regulation webs operates in the transition from affluent to barren conditions, with σS being the chief actor in a company of players that stage a competition for the sparsely available RNA polymerase molecules. In this role, σS may be assisted by several factors, including nucleoid-related proteins and metabolites. In addition, the levels of σS itself are regulated by mechanisms that include inactivation and degradation. Several transcription factors, belonging to different regulatory pathways, may operate in the same promoter. In such a case, the final transcriptional output depends both on the interplay of effectors and on the properties of the recruitment of the effector–RNA polymerase complex to the promoter. RNA polymerase itself is also capable of establishing selective interactions with activators and specific promoter regions through the carboxy-terminal domain of its alpha subunit (αCTD). Transcriptional regulation controls pervade such crucial events in the life of bacterial cells as Escherichia coli cell division, Bacillus subtilis sporulation and Caulobacter crescentus differentiation. These examples suggest that bacteria have been particularly inventive in adapting gene expression regulation to survive under a diversity of environments and have done so by exploiting the malleable molecular mechanisms involved in transcription, developing complexities that may match those found in eukaryotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01445.x
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  • 3
    Electronic Resource
    Electronic Resource
    A developmentally regulated gene encoding a repressor-like protein is essential for sporulation in Streptomyces coelicolor A3(2) (1998)
    Oxford BSL : Blackwell Science Ltd, UK
    Molecular microbiology 29 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: whiH is one of several known loci specifically needed for the orderly multiple sporulation septation of aerial hyphae of Streptomyces coelicolor A3(2) and for the expression of at least some late sporulation genes. DNA complementing whiH mutants was located immediately upstream of hrdB, which encodes the principal σ factor of S. coelicolor. Sequencing revealed a gene whose disruption gave rise to a typical whiH mutant phenotype. Four whiH mutants contained base changes or a frameshift in this gene. The deduced product of whiH is related to a large family of bacterial regulatory proteins, the most similar being several repressors (such as GntR of Bacillus subtilis) responsive to carboxylate-containing intermediates in carbon metabolism. Transcription of whiH was initiated at a single promoter, PwhiH. Levels of whiH mRNA were developmentally regulated, increasing sharply when aerial mycelium was present, and reaching a maximum approximately when spores were first detectable. Transcript levels were markedly increased in a whiH mutant, indicating the possible involvement of WhiH in negative regulation of its own production. PwhiH was directly dependent on the σ factor encoded by another sporulation gene, whiG, as shown by in vivo and in vitro transcription analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00939.x
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  • 4
    Electronic Resource
    Electronic Resource
    Complex transcription of an operon encoding the Sail restriction-modification system of Streptomyces albus G (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 8 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: High-resolution SI nuclease mapping of mRNA synthesised in vivo, in vitro run-off transcription with RNA polymerase from Streptomyces lividans and gene fusions were used to analyse the transcriptional organization of the Sall restriction-modification system of Streptomyces albus G. The sallR and sallM genes that encode the restriction endonuclease and its cognate methyltransferase constitute an operon which is mainly transcribed from sal-pR1, a promoter located immediately upstream of saIIR, with two possible minor promoters further upstream. Another promoter, sal-pM, is within the 3′ end of the saIIR coding region, and allows expression of the modification gene in the absence of sal-pR1. The sal-pM promoter might be involved in the establishment of modification prior to restriction endonuclease activity. Sequences upstream of the apparent transcriptional start sites for sat-pR1 and sal-pM show similarity with the −10 region of typical vegetatively expressed eubacterial promoters, but appropriately centered −35 regions are absent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01568.x
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  • 5
    Electronic Resource
    Electronic Resource
    The positions of the sigma-factor genes, whiG and sigF, in the hierarchy controlling the development of spore chains in the aerial hyphae of Streptomyces coelicolor A3(2) (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: whiG and sigF encode RNA polymerase sigma factors required for sporulation in the aerial hyphae of Streptomyces coelicolor. Their expression was analysed during colony development in wild-type and sporulation-defective whi mutant strains. Each gene was transcribed from a single promoter. Unexpectedly, whiG mRNA was present at all time points, including those taken prior to aerial mycelium formation; this suggests that whiG may be regulated post-transcriptionally. Transcription of whiG did not depend upon any of the six known‘early’whi genes required for sporulation septum formation (whiA, B, G, H, /and J), placing it at the top of the hierarchy of whi loci. sigF expression appeared to be regulated at the level of transcription; sigF transcripts were detected transiently when sporulation septa were observed in the aerial hyphae. Transcription of sigF depended upon all six of the early whi genes, including whiG. The sigF promoter does not resemble the consensus sequence established for σWhiG-dependent promoters and EnWhiG did not transcribe from the sigF promoter in vitro. Consequently, the genetic dependence of sigF upon whiG is very likely to be indirect. These results show that there is a hierarchical relationship between sigma factors required for Streptomyces sporulation and also that at least five other genes are involved in this transcriptional network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1996.tb02567.x
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  • 6
    Electronic Resource
    Electronic Resource
    A response regulator-like protein that functions at an intermediate stage of sporulation in Streptomyces coelicolor A3(2) (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: whiI is one of several loci originally described as essential for sporulation in Streptomyces coelicolor A3(2). We have characterized whiI at the molecular level. It encodes an atypical member of the response regulator family of proteins, lacking at least two of the residues strongly conserved in the conventional phosphorylation pocket. It is not adjacent to a potential sensor kinase gene. Fifteen mutant alleles of whiI were sequenced, revealing, among others, six mutations affecting conserved amino acids, several frameshift mutations and one mutation in the promoter. The whiI promoter is specifically transcribed by the sporulation-specific σWhiG-containing form of RNA polymerase. Transcription of whiI is temporally controlled, reaching a maximum level coincident with the formation of spores. Further transcriptional studies suggested that WhiI is involved directly or indirectly in repressing its own expression and that of another σWhiG-dependent sporulation-specific regulatory gene, whiH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01630.x
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  • 7
    Electronic Resource
    Electronic Resource
    Tissue-specific glycogen branching isoenzymes in a multicellular prokaryote, Streptomyces coelicolor A3(2) (1995)
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Science Ltd
    Molecular microbiology 18 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In the overtly differentiated colonies of Streptomyces coelicolor A3(2), discrete phases of glycogen synthesis are found at the vegetative/aerial mycelium boundary (phase I) and in the immature spore chains at aerial hyphal tips (phase II). We have characterized two S. coelicolor glgB genes encoding glycogen branching enzyme, which are well separated in the genome. Disruption of glgBI led to the formation of abnormal polyglucan deposits at phase I, with phase II remaining normal, whereas disruption of glgBII interfered specifically with phase II deposits, and not with those of phase I. Thus, each branching enzyme isoform is involved in a different phase of glycogen synthesis. This situation contrasts with that in simple bacteria, which typically have a single set of enzymes for glycogen metabolism, and more closely resembles that in plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.mmi_18010089.x
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic analysis of the φC31 -specific phage growth limitation (Pgl) system of Streptomyces coelicolor A3(2) (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 7 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The phage growth limitation (Pgl) system of Streptomyces coelicolor A3(2) was shown to be specific to φC31 homo-immune phages, and to be absent from the closely related strain Streptomyces Iividans. A 16 kb fragment of S. coelicolor A3(2) DNA was isolated which complemented the Pgl− phenotype of J1501, a pgl mutant derivative of the PgltsS. coelicolor strain M130. The cloned DNA complemented only half of the available pgl mutants, which therefore represented at least two groups, designated Pgl class A and class B strains. It follows that more than one kind of high-frequency genetic event can lead to the Pgl− phenotype. Crosses between class A and class B strains yielded high frequencies of Pgl+ recombinants. Crosses between strains of the same class gave no Pgl+ recombinants. The cloned DNA was altered by deletion or apparent point mutation upon passage through the two class B strains tested, such that it was no longer capable of complementing class A strains. This accumulation of mutations might suggest that the expression of the cloned DNA is toxic to at least some class B strains. The nature of the genetic instability associated with the Pgl system was not detectable by Southern blot analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01124.x
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  • 9
    Electronic Resource
    Electronic Resource
    Alternative oxygen-dependent and oxygen-independent ribonucleotide reductases in Streptomyces: cross-regulation and physiological role in response to oxygen limitation (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 54 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Ribonucleotide reductases (RNRs) catalyse the conversion of ribonucleotides to deoxyribonucleotides and are essential for de novo DNA synthesis and repair. Streptomyces spp. contain genes coding for two RNRs. We show here that the Streptomyces coelicolor M145 nrdAB genes encoding an oxygen-dependent class I RNR are co-transcribed with nrdS, which encodes an AraC-like regulatory protein. Likewise, the class II oxygen-independent RNR nrdJ gene forms an operon with a likely regulatory gene, nrdR, which encodes a protein possessing an ATP-cone domain like those present in the allosteric activity site of many class Ia RNRs. Deletions in nrdB and nrdJ had no discernible effect on growth individually, but abolition of both RNR systems, using hydroxyurea to inactivate the class Ia RNR (NrdAB) in the nrdJ deletion mutant, was lethal, establishing that S. coelicolor possesses just two functional RNR systems. The class II RNR (NrdJ) may function to provide a pool of deoxyribonucleotide precursors for DNA repair during oxygen limitation and/or for immediate growth after restoration of oxygen, as the nrdJ mutant was slower in growth recovery than the nrdB mutant or the parent strain. The class Ia and class II RNR genes show complex regulation. The nrdRJ genes were transcribed some five- to sixfold higher than the nrdABS genes in vegetative growth, but when nrdJ was deleted, nrdABS transcription was upregulated by 13-fold. In a reciprocal experiment, deletion of nrdB had little effect on nrdRJ transcription. Deletion of nrdR caused a dramatic increase in transcription of nrdJ and to a less extent nrdABS, whereas disruption of cobN, a gene required for synthesis of coenzyme B12 a cofactor for the class II RNR, caused similar upregulation of transcription of nrdRJ and nrdABS. In contrast, deletion of nrdS had no detectable effect on transcription of either set of RNR genes. These results establish the existence of control mechanisms that sense and regulate overall RNR gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04325.x
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  • 10
    Electronic Resource
    Electronic Resource
    The ParB protein of Streptomyces coelicolor A3(2) recognizes a cluster of parS sequences within the origin-proximal region of the linear chromosome (2002)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 45 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Summary The mycelial prokaryote Streptomyces coelicolor A3(2) possesses a large linear chromosome (8.67 Mb) with a centrally located origin of replication (oriC). Recently, chromosome partitioning genes (parA and parB) and putative ParB binding sites (parS sequences) were identified in its genome. The S. coelicolor chromosome contains more parS sequ­ences than any other bacterial chromosome characterized so far. Twenty of the 24 parS sequences are densely packed within a relatively short distance (≈ 200 kb) around oriC. A series of in vitro and in vivo experiments showed that S. coelicolor ParB protein interacts specifically with the parS sequences, albeit with a rather low affinity. Our results suggested that the binding of ParB is not only determined by the parS sequence, but also by the location of target DNA close to oriC. The unusually high number and close proximity to each other of the parS sites, together with in vivo and in vitro evidence that multiple ParB molecules may assemble along the DNA from an initial ParB–parS complex, suggest that a large DNA segment around the replication origin may form a massive nucleoprotein complex as part of the replication-partitioning cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03102.x
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