The small 6C RNA of Corynebacterium glutamicum is involved in the SOS response

Abstract

The 6C RNA family is a class of small RNAs highly conserved in Actinobacteria, including the genera Mycobacterium, Streptomyces and Corynebacterium whose physiological function has not yet been elucidated. We found that strong transcription of the cgb_03605 gene, which encodes 6C RNA in C. glutamicum, was driven by the SigA- and SigB-dependent promoter Pcgb_03605. 6C RNA was detected at high level during exponential growth phase (180 to 240 molcules per cell) which even increased at the entry of the stationary phase. 6C RNA level did not decrease within 240 min after transcription had been stopped with rifampicin, which suggests high 6C RNA stability. The expression of cgb_03605 further increased approximately twofold in the presence of DNA-damaging mitomycin C (MMC) and nearly threefold in the absence of LexA. Deletion of the 6C RNA gene cgb_03605 resulted in a higher sensitivity of C. glutamicum toward MMC and UV radiation. These results indicate that 6C RNA is involved in the DNA damage response. Both 6C RNA level-dependent pausing of cell growth and branched cell morphology in response to MMC suggest that 6C RNA may also be involved in a control of cell division.

Comparative genomics of Mycobacterium mucogenicum and Mycobacterium neoaurum clade members emphasizing tRNA and non-coding RNA

“…Close to the Ms1 RNA gene we identified the presence of the gene encoding 6C RNA, which is widespread among Actinobacteria [76, 77]. Its location relative to the Ms1 RNA gene is conserved, with one gene in between, comparing the mycobacteria studied here and S. coelicolor (Fig.…”

“…Its location is conserved relative to the Ms1 RNA gene among different Actinobacteria and the level of 6C RNA is higher in Mmuc T cells in stationary phase compared to exponentially growing cells, albeit not as pronounced as for Ms1 RNA. The expression of 6C RNA has also been detected in other mycobacteria, Cornynebacterium glutamicum and S. coelicolor [76, 77, 103, 104]. In S. coelicolor , 6C RNA is upregulated during development/sporulation and it has been discussed that it reflects dormancy and slower metabolism [76].…”

“…In S. coelicolor , 6C RNA is upregulated during development/sporulation and it has been discussed that it reflects dormancy and slower metabolism [76]. For C. glutamicum , it is suggested to be involved in the SOS response and possibly also in the control of cell division as well as the GlxR, a regulator of carbon source metabolism and energy conversion, regulatory network [77, 105]. The role of mycobacterial 6C RNA is unknown but from the discussion above it is conceivable that it is involved in regulating cell shape and development including dormancy and spore formation in mycobacteria [97, 98], for a review see [99].…”

Mycobacterium tuberculosis 6C sRNA binds multiple mRNA targets via C-rich loops independent of RNA chaperones

“…The 5′ UTRs of dnaB mRNA from S. coelicolor and C. glutamicum also contain a G-rich sequence, which could potentially bind their cognate 6C sRNA through the C-rich loops (L2 and L3) (Supplementary Figure S8C and D). Targeting dnaB may provide an explanation for the previous observations that overexpression of 6C sRNA caused a defective growth in C. glutamicum (23) and was associated with hyphae formation and sporulation in S. coelicolor (20). Future studies to test this hypothesis are warranted.…”

“…Constructs overexpressing 6C sRNA of M. tb were lethal to M. tb and caused defective growth in M. smegmatis (21). A defective growth phenotype was also observed in Corynebacterium glutamicum overexpressing 6C sRNA (23). These observations suggest that 6C sRNA may play a role in regulation of cell division.…”