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  • Blackwell Science Ltd  (5)
  • 1
    Electronic Resource
    Electronic Resource
    afsS is a target of AfsR, a transcriptional factor with ATPase activity that globally controls secondary metabolism in Streptomyces coelicolor A3(2) (2002)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 43 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: AfsR is a pleiotropic, global regulator that controls the production of actinorhodin, undecylprodigiosin and calcium-dependent antibiotic in Streptomyces coelicolor A3(2). AfsR, with 993 amino acids, is phosphorylated on serine and threonine residues by a protein serine/threonine kinase AfsK and contains an OmpR-like DNA-binding fold at its N-terminal portion and A- and B-type nucleotide-binding motifs in the middle of the protein. The DNA-binding domain, in-dependently of the nucleotide-binding domain, contributed the binding of AfsR to the upstream region of afsS that locates immediately 3′ to afsR and encodes a 63-amino-acid protein. No transcription of afsS in the ΔafsR background and restoration of afsS transcription by afsR on a plasmid in the same genetic background indicated that afsR served as a transcriptional activator for afsS. Interestingly, the AfsR binding site overlapped the promoter of afsS, as determined by DNase I protection assay and high-resolution S1 nuclease mapping. The nucleotide-binding domain contributed distinct ATPase and GTPase activity. The phosphorylation of AfsR by AfsK greatly enhanced the DNA-binding activity and modulated the ATPase activity. The DNA-binding ability of AfsR was independent of the ATPase activity. However, the ATPase activity was essential for transcriptional activation of afsS, probably because the energy available from ATP hydrolysis is required for the isomerization of the closed complex between AfsR and RNA polymerase to a transcriptionally competent open complex. Thus, AfsR turns out to be a unique transcriptional factor, in that it is modular, in which DNA-binding and ATPase activities are physically separable, and the two functions are modulated by phosphorylation on serine and threonine residues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.02840.x
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  • 2
    Electronic Resource
    Electronic Resource
    The A-factor regulatory cascade leading to streptomycin biosynthesis in Streptomyces griseus : identification of a target gene of the A-factor receptor (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: In Streptomyces griseus, A-factor (2-isocapryloyl-3R-hydroxymethyl-γ-butyrolactone) at an extremely low concentration triggers streptomycin biosynthesis and cell differentiation by binding a repressor-type receptor protein (ArpA) and dissociating it from DNA. An A-factor-responsive transcriptional activator (AdpA) able to bind the promoter of strR, a pathway-specific regulatory gene responsible for transcription of other streptomycin biosynthetic genes, was purified to homogeneity and adpA was cloned by PCR on the basis of amino acid sequences of purified AdpA. adpA encoding a 405-amino-acid protein containing a helix-turn-helix DNA-binding motif at the central region showed sequence similarity to transcriptional regulators in the AraC/XylS family. The −35 and −10 regions of the adpA promoter were found to be a target of ArpA; ArpA bound the promoter region in the absence of A-factor and exogenous addition of A-factor to the DNA–ArpA complex immediately released ArpA from the DNA. Consistent with this, S1 nuclease mapping showed that adpA was transcribed only in the presence of A-factor and strR was transcribed only in the presence of intact adpA. Furthermore, adpA disruptants produced no streptomycin and overexpression of adpA caused the wild-type S. griseus strain to produce streptomycin at an earlier growth stage in a larger amount. On the basis of these findings, we propose here a model to demonstrate how A-factor triggers streptomycin biosynthesis at a late exponential growth stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01579.x
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  • 3
    Electronic Resource
    Electronic Resource
    DNA-binding activity of the A-factor receptor protein and its recognition DNA sequences (1997)
    Oxford UK : Blackwell Science Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The A-factor receptor protein (ArpA) containing an α-helix-turn-α-helix DNA-binding consensus sequence at its N-terminal portion plays a key role in the regulation of secondary metabolism and cell differentiation in Streptomyces griseus. A binding site forming a palindrome 24 bp in length was initially recovered from a pool of random-sequence oligonucleotides by rounds of a binding/immunoprecipitation/amplification procedure with histidine-tagged ArpA and anti-ArpA antibody. By means of further binding/gel retardation/amplification experiments on the basis of the recovered sequence, a 22 bp palindromic binding site with the sequence 5′-GG(T/C)CGGT(A/T)(T/C)-G(T/G)-3′ as one half of the palindrome was deduced as a consensus sequence recognized and bound by ArpA. ArpA did not bind to the binding site in the presence of its ligand, A-factor. In addition, exogenous addition of A-factor to the ArpA–DNA complex induced immediate release of ArpA from the DNA. All of these data are consistent with the idea, obtained from previous genetic studies, that ArpA acts as a repressor-type regulator for secondary metabolism and cellular differentiation by preventing the expression of a certain key gene(s) during the early growth phase. A-factor, produced in a growth-dependent manner, releases ArpA from the DNA, thus switching on the expression of the key gene(s), leading to the onset of secondary metabolism and aerial mycelium formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.4081772.x
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  • 4
    Electronic Resource
    Electronic Resource
    DNA-binding specificity of AdpA, a transcriptional activator in the A-factor regulatory cascade in Streptomyces griseus (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 53 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: AdpA, belonging to the AraC/XylS family, is the key transcriptional activator for a number of genes of various functions in the A-factor regulatory cascade in Streptomyces griseus. It consists of a ThiJ/PfpI/DJ-1-like dimerization domain at its N-terminal portion and a DNA-binding domain with two helix–turn–helix motifs at its C-terminal portion, representing a large subgroup of the AraC/XylS family. Uracil interference assay and missing T and GA interference assays on several AdpA binding sites, followed by gel mobility shift assays on systematically mutated binding sites, revealed a consensus AdpA-binding sequence, 5′-TGGCSNGWWY-3′ (S: G or C; W: A or T; Y: T or C; N: any nucleotide). A dimer of AdpA bound a site including the two consensus sequences, with a space of 13–14 bp, as an inverted repeat (type I) at various positions, for example more than 200 bp upstream (−200) and 25 bp downstream (+25) from the transcriptional start point of the target gene. In addition, AdpA also bound a site including the consensus sequence in a single copy (type II) at positions, in most cases, from −40 to −50 and from −50 to −60. For transcriptional activation, some genes required simultaneous binding of a dimer of AdpA to type I and II sites, but others required only a single type I or type II site. AdpA bound mutated type I sites with various distances between the two consensus sequences with significant affinities, although the optimal distances for AdpA to bind were 13–14 bp and 2 bp. The DNA-binding domain is therefore connected to the ThiJ/PfpI/DJ-1-like dimerization domain with a flexible linker. The DNA-binding specificity of AdpA in conjunction with that of other AraC/XylS family members is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04153.x
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  • 5
    Electronic Resource
    Electronic Resource
    Signalling early developmental events in two highly diverged Streptomyces species (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 48 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We review three main aspects of extracellular signalling in the initiation of aerial mycelium formation in two phylogenetically distant streptomycetes, S. coelicolor A3(2) and S. griseus: (1) γ -butyrolactones; (2) a complex cascade of mostly undefined signals; and (3) progress towards defining an integrating endpoint of all this signalling. Although apparent orthologues of many of the genes involved are found in both species, some of the connectivities are different. Moreover, some of the genes involved in signalling have diverged more rapidly than known housekeeping genes. We propose that that this may be an important aspect of speciation, and that the differences in gene interactions may reflect the diverse soil microecologies to which different streptomycetes are adapted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03476.x
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