afsR is a pleiotropic but conditionally required regulatory gene for antibiotic production in Streptomyces coelicolor A3(2)

Abstract

The N-terminal region of AfsR, a putative pleiotropic regulatory protein for antibiotic production in Streptomyces coelicolor A3(2), is homologous to RedD and Actil-ORF4, pathway-specific regulatory proteins required for the production of the antibiotics undecylprodigiosin (Red) and actinorhodin (Act), respectively. The recent identification of afsS, which lies immediately 3' of afsR and which stimulates antibiotic production when cloned at high copy number, questioned whether afsR was a pleiotropic regulatory gene. In this study we demonstrate that multiple copies of afsR can stimulate both Act and Red production and that, despite its homology, it cannot substitute for the pathway-specific regulatory genes. Moreover, an in-frame deletion that removed most of the afsR coding sequence resulted in loss of Act and Red production, and a marked reduction in the synthesis of the calcium-dependent antibiotic (CDA), but only under some (non-permissive) nutritional conditions. Although additional copies of afsR resulted in elevated levels of the actII-ORF4 and redD transcripts, transcription of the pathway-specific regulatory genes under non-permissive conditions was unaffected by deletion of afsR. While afsR may operate independently of the pathway-specific regulatory proteins to influence antibiotic production, the activity of ActII-ORF4 and of RedD under non-permissive conditions could depend on interaction with, or modification by, AfsR.

Oxazolomycin Biosynthesis in Streptomyces albus JA3453 Featuring an “Acyltransferase-less” Type I Polyketide Synthase That Incorporates Two Distinct Extender Units

“…OzmR shows significant similarity to the LysR family of regulators, such as Orf5 (accession number BAA32133; 53% identity) from Streptomyces griseus (38), whereas OzmU belongs to the SARP family of regulators, including Orf31* (accession number CAG15043; 37% identity) involved in glycopeptide teicoplanin biosynthesis in Actinoplanes teichomyceticus (39), AfsR (accession number BAA14186; 33% identity) in Streptomyces coelicolor, a pleiotropic antibiotic regulator (40), and RubS (accession number AAM97369; 30% identity) involved in rubromycin biosynthesis in Streptomyces collinus. Although OzmT resembles other Thr-tRNA synthetases, such as SCH63.25 (CAC 10316, 77/83) in S. coelicolor, its exact roles still need to be determined.…”

The Streptomyces coelicolor A3(2) lipAR operon encodes an extracellular lipase and a new type of transcriptional regulator The GenBank accession numbers for the sequences described in this paper are AF009336 and U03114.

“…Two regulatory proteins, AcoK and AlkS, from Gram-negative organisms are involved, like MalT, in regulating catabolic functions (acetoin and alkane degradation, respectively ; Peng et al, 1997 ;Yuste et al, 1998). Several members of this protein family come from streptomycetes ; the LipR proteins are clearly involved in regulating a catabolic function, whereas others appear to be involved in regulating antibiotic synthesis, either as part of a cluster (PikD, RapH and its homologue RapHh ; Xue et al, 1998 ;Molnar et al, 1996 ;Ruan et al, 1997) or as pleiotropic regulators (AfsR ; Floriano & Bibb, 1996). Analysis of sequence relationships revealed that the Streptomyces proteins group according to function, with those that are part of antibiotic biosynthesis clusters forming one sub-group, and LipR belonging to another.…”

Origin and evolution of eukaryotic apoptosis: the bacterial connection

“…Effectively, the only available data point to a role of some of these proteins, such as GutR from Bacillus subtilis and AfsR from Streptomyces coelicolor, in transcription regulation. 57,58 The GutR protein, which is a regulator of the glucitol operon, has been shown to function in an ATP-dependent manner. 59 The AfsR protein is a global regulator of physiological and morphological differentiation in Streptomyces and is itself regulated by reversible phosphorylation catalyzed by the serine-threonine kinase AfsK.…”