AterDDomain-Encoding Gene (SCO2368) Is Involved in Calcium Homeostasis and Participates in Calcium Regulation of a DosR-Like Regulon in Streptomyces coelicolor
AlthoughStreptomyces coelicoloris not resistant to tellurite, it possesses several TerD domain-encoding (tdd) genes of unknown function. To elucidate the function oftdd8, the transcriptomes ofS. coelicolorstrain M145 and of atdd8deletion mutant derivative (the Δtdd8strain) were compared. Several orthologs ofMycobacterium tuberculosisgenes involved in dormancy survival were upregulated in the deletion mutant at the visual onset of prodiginine production. These genes are organized in a putative redox stress response cluster comprising two large loci. A binding motif similar to the dormancy survival regulator (DosR) binding site ofM. tuberculosishas been identified in the upstream sequences of most genes in these loci. A predicted role for these genes in the redox stress response is supported by the low NAD+/NADH ratio in the Δtdd8strain. ThisS. coelicolorgene cluster was shown to be induced by hypoxia and NO stress. While thetdd8deletion mutant (the Δtdd8strain) was unable to maintain calcium homeostasis in a calcium-depleted medium, the addition of Ca2+in Δtdd8culture medium reduced the expression of several genes of the redox stress response cluster. The results shown in this work are consistent with Tdd8 playing a significant role in calcium homeostasis and redox stress adaptation.