Lee JH, Lee EJ, Roe JH. uORF-mediated riboregulation controls transcription of whiB7/wblC antibiotic resistance gene.
Mol Microbiol 2021;
117:179-192. [PMID:
34687261 DOI:
10.1111/mmi.14834]
[Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 10/05/2021] [Accepted: 10/19/2021] [Indexed: 11/27/2022]
Abstract
WhiB7/WblC is a transcriptional factor of actinomycetes conferring intrinsic resistance to multiple translation-inhibitory antibiotics. It positively autoregulates its own transcription in response to the same antibiotics. The presence of a uORF and a potential Rho-independent transcription terminator in the 5' leader region has suggested a possibility that the whiB7/wblC gene is regulated via a uORF-mediated transcription attenuation. However, experimental evidence for the molecular mechanism to explain how antibiotic stress suppresses the attenuator, if any, and induces transcription of the whiB7/wblC gene has been lacking. Here we report that the 5' leader sequences of the whiB7/wblC genes in sub-clades of actinomycetes include conserved antiterminator RNA structures. We confirmed that the putative antiterminator in the whiB7/wblC leader sequences of both Streptomyces and Mycobacterium indeed suppresses Rho-independent transcription terminator and facilitates transcription readthrough, which is required for WhiB7/WblC-mediated antibiotic resistance. The antibiotic-mediated suppression of the attenuator can be recapitulated by amino acid starvation, indicating that translational inhibition of uORF by multiple signals is a key to induce whiB7/wblC expression. Our findings of a mechanism leading to intrinsic antibiotic resistance could provide an alternative to treat drug-resistant mycobacteria.
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