Trans-translation is involved in the CcpA-dependent tagging and degradation of TreP in Bacillus subtilis.

TreP [trehalose-permease (phosphotransferase system (PTS) trehalose-specific enzyme IIBC component)] is one of the target proteins of tmRNA-mediated trans-translation in Bacillus subtilis [Fujihara et al. (2002) Detection of tmRNA-mediated trans-translation products in Bacillus subtilis. Genes Cells, 7, 343-350]. The TreP synthesis is subject to CcpA-dependent carbon catabolite repression (CCR), and the treP gene contains catabolite-responsive element (cre) sequence, a binding site of repressor protein CcpA, in the coding region. Here, we demonstrated that the tmRNA-tagging of TreP occurs depending on the gene for CcpA. In the presence of CcpA, the transcription of treP mRNA terminates at 8-9 nucleotides upstream of the 5'-edge of the internal cre sequence, and translational switch to the tag-sequence occurs at the 101st amino-acid (asparagine) position from N-terminus of TreP. The results show that trans-translation reaction is involved in the tagging and degradation of the N-terminal TreP fragment produced by truncated mRNA, which is a product of transcriptional roadblock by CcpA binding to the cre sequence in the internal coding region.