title: DarR, a TetR-like transcriptional factor, is a cyclic di-AMP-responsive repressor in Mycobacterium smegmatis.
abstract: Cyclic dinucleotides, including cyclic di-AMP (c-di-AMP), are known to be ubiquitous second messengers involved in bacterial signal transduction. However, no transcriptional regulator has been characterized as a c-di-AMP receptor/effector to date. In the present study, using a c-di-AMP/transcription factor binding screen, we identified Ms5346, a TetR family regulator in Mycobacterium smegmatis, as a c-di-AMP receptor in bacteria. Ms5346 could specifically bind c-di-AMP with K(d) of 2.3 ± 0.5 μM. Using EMSA and DNase I footprinting assays, c-di-AMP was found to stimulate the DNA binding activity of Ms5346 and to enhance its ability to protect its target DNA sequence. A conserved 14-bp palindromic motif was identified as the DNA-binding site for Ms5346. Further, Ms5346 was found to negatively regulate expression of three target genes including Ms5347 (encoding a major facilitator family transporter), Ms5348 (encoding a medium chain fatty acyl-CoA ligase), and Ms5696 (encoding a cold shock protein, CspA). Ms5346 is the first cyclic di-AMP receptor regulator to be identified in bacteria, and we have designated it as DarR. Our findings enhance our understanding of the function and regulatory mechanism of the second messenger c-di-AMP in bacteria.
authors.affiliation: National Key Laboratory of Agricultural Microbiology, Center for Proteomics Research, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Weihui
authors.initials: W
authors.lastname: Li
authors.forename: Zheng-Guo
authors.initials: ZG
authors.lastname: He
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000378:metabolism; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D005227:Fatty Acids / Q000096:biosynthesis; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D055029:Inverted Repeat Sequences / Q000235:genetics; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D059372:Nucleotide Motifs / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015226:Dinucleoside Phosphates; D005227:Fatty Acids; D012097:Repressor Proteins; C528998:cyclic diadenosine phosphate