Function
Toxic component of a type II toxin-antitoxin (TA) system. A sequence-specific endoribonuclease, cleavage occurs after the first AU in the consensus sequence AUA(U/A); RNA secondary structure is probably important in substrate choice. Cuts in 5' and 3' UTRs. The TA system acts as a post-transcriptional regulator of carbon metabolism; in M.smegmatis 3 TA systems (VapB-VapC, MazE-MazF and Phd-Doc) may be involved in monitoring the nutritional supply and physiological state of the cell, linking catabolic with anabolic reactions. When overexpressed inhibits cell growth, via translation; 10-fold in a wild-type strain, 100-fold in a vapB-vapC disruption mutant (PubMed:19445953). Overexpression of VapC leads to differential expression of 205 genes; many down-regulated genes are predicted to be involved in the transport and catabolism of carbohydrates, while genes involved in phosphate transport and scavenging are up-regulated. VapC is bacteriostatic, not bacteriocidal; cells are ovoid, non-replicating and have decreased transcription, becoming dormant (PubMed:24417293). Digests ssRNA but not tRNA, dsRNA, ssDNA or dsDNA. The VapB-VapC complex binds its own promoter DNA, and VapC alone binds RNA.