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Importance and regulation of inositol biosynthesis during growth and differentiation of Streptomyces
Author(s) -
Zhang Guohua,
Tian Yuqing,
Hu Kun,
Zhu Yu,
Chater Keith F.,
Feng Chi,
Liu Gang,
Tan Huarong
Publication year - 2012
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2012.08000.x
Subject(s) - biology , inositol , regulator , streptomyces coelicolor , mutant , biochemistry , response regulator , gene , regulation of gene expression , transcription (linguistics) , inositol phosphate , streptomyces , regulator gene , transcription factor , microbiology and biotechnology , genetics , bacteria , receptor , linguistics , philosophy
Summary Unusually among bacteria, actinobacteria possess myo‐inositol 1‐phosphate synthase (mIPS). In the developmentally complex Streptomyces coelicolor, the mIPS‐encoding gene ( inoA ) is cotranscribed with a putative regulatory gene ( inoR ). The inoRA transcript was more abundant in an inoR in‐frame deletion mutant, and InoR formed different complexes in vitro with an extensive region around the inoRA promoter. Binding was relieved by adding glucose 6‐phosphate. Thus, InoR is a metabolite‐sensitive autorepressor that influences inoA expression , and hence the level of inositol, by controlling transcription from P inoRA . Disruption of inoA resulted in inositol‐dependent growth and development, with full phenotypic correction at 0.1 mM inositol: at lower inositol concentrations differentiation was arrested at intermediate stages. This pattern may partly reflect increased demand for membrane phospholipids during sporulation septation. A corresponding sharp upregulation of inoRA transcription coincident with sporulation was dependent on a developmental regulator, WhiI. A truncated form of WhiI could bind two sites downstream of P inoRA , and one of the WhiI‐binding sites overlapped the InoR‐binding site. The combined action of a metabolic regulator and a developmental regulator at the simple P inoRA promoter is a previously undescribed strategy for the differential provision of developmentally appropriate levels of a substance required during the formation of spore chains.