A developmentally regulated gene encoding a repressor‐like protein is essential for sporulation in Streptomyces coelicolor A3(2)

Abstract

SummarywhiH 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 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, P whiH . 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. P whiH was directly dependent on the factor encoded by another sporulation gene, whiG, as shown by in vivo and in vitro transcription analysis.

Taking a genetic scalpel to the Streptomyces colony

“…different bacteria (Ryding et al, 1998) repress their own production, and indeed whiH transcription was markedly increased in a whiH point mutant (Ryding et al, 1998). Based on these observations and analogies, we hypothesize that WhiH can repress certain target promoters, and that this repression can be relieved by interaction with an unknown carbon metabolite whose concentration increases during the development of aerial hyphae (Ryding et al, 1998).…”

“…Based on these observations and analogies, we hypothesize that WhiH can repress certain target promoters, and that this repression can be relieved by interaction with an unknown carbon metabolite whose concentration increases during the development of aerial hyphae (Ryding et al, 1998). It may be relevant that several of the carboxylic acids that regulate WhiH-like proteins in E. coli are close to the anapleurotic interface whose modulation plays an important role in determining carbon flux to alternative sinks such as growth-associated biomass or storage metabolites (Fig.…”

The interplay of glycogen metabolism and differentiation provides an insight into the developmental biology of Streptomyces coelicolor

“…The expression of glgBII therefore depends on whiG, but not on whiH or I (both of which are themselves directly and completely whiG-dependent; Ryding et al, 1998;Aínsa et al, 2000) or whiA or B (which are whiG-independent; Aínsa et al, 1999). The abundance of aerial-mycelium-associated glycogen in whiG mutants may reflect the absence of WhiH from such mutants, if WhiH does indeed influence the quantity of glycogen in aerial hyphae (see above).…”

“…To introduce hyg-disrupted versions of whi genes into J1508, DNA from previously constructed disruptants of S. coelicolor M145 (Ryding et al, 1998;Flärdh et al, 1999;Aínsa et al, 2000) was denatured and used to transform J1508 protoplasts as described by Oh & Chater (1997). Details of the constructed strains are given in Table 1.…”

“…Mutants in the remaining well-studied early whi genes display at least some coiling of aerial hyphal tips (Chater et al, 1989;Flärdh et al, 1999). Among theses genes, whiA encodes a protein of unknown function with orthologues in several other Gram-positive bacteria (Aínsa et al, 2000); whiB belongs to a gene group whose products code for actinomycete-specific small cysteine-rich regulatory proteins of unknown structure (Davis & Chater, 1992;Soliveri et al, 2000); whiH encodes a member of the GntR family of transcription factors (Ryding et al, 1998); and whiI encodes an atypical member of the kind of response regulator usually associated with histidine protein kinases in bacterial two-component systems (Aínsa et al, 1999). Both whiH and whiI are direct targets for RNA polymerase holoenzyme containing s WhiG (Ryding et al, 1998;Aínsa et al, 1999).…”