Zinc-responsive regulation of alternative ribosomal protein genes in Streptomyces coelicolor involves zur and sigmaR.
Streptomyces coelicolor contains paralogous versions of seven ribosomal proteins (S14, S18, L28, L31, L32, L33, and L36), which differ in their potential to bind structural zinc. The paralogues are termed C(+) or C(-) on the basis of the presence or absence of putative cysteine ligands. Here, mutational studies suggest that the C(-) version of L31 can functionally replace its C(+) paralogue only when expressed at an artificially elevated level. We show that the level of expression of four transcriptional units encoding C(-) proteins is elevated under conditions of zinc deprivation. Zur controls the expression of three transcriptional units (including rpmG2, rpmE2, rpmB2, rpsN2, rpmF2, and possibly rpsR2). Zur also controls the expression of the znuACB operon, which is predicted to encode a high-affinity zinc transport system. Surprisingly, the zinc-responsive control of the rpmG3-rpmJ2 operon is dictated by sigma(R), a sigma factor that was previously shown to control the response to disulfide stress in S. coelicolor. The induction of sigma(R) activity during zinc limitation establishes an important link between thiol-disulfide metabolism and zinc homeostasis.
Owen
Gillian A
GA
Department of Biochemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
Pascoe
Ben
B
Kallifidas
Dimitris
D
Paget
Mark S B
MS
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001483:Base Sequence; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon / Q000235:genetics; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D048372:Streptomyces coelicolor / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015032:Zinc / Q000172:deficiency / Q000494:pharmacology*
D001426:Bacterial Proteins; D012269:Ribosomal Proteins; D012808:Sigma Factor; D015032:Zinc