| Type: | Family | Name: | Competence operon E, ComEB |
| Description: | Competence is the ability of a cell to take up exogenous DNA from its environment, resulting in transformation. It is widespread among bacteria and is probably an important mechanism for the horizontal transfer of genes. DNA usually becomes available by the death and lysis of other cells. Competent bacteria use components of extracellular filaments called type 4 pili to create pores in their membranes and pull DNA through the pores into the cytoplasm. This process, including the development of competence and the expression of the uptake machinery, is regulated in response to cell-cell signalling and/or nutritional conditions [].The development of genetic competence in Bacillus subtilisis a highly regulated adaptive response to stationary-phase stress. For competence to develop, the transcriptional regulator, ComK, must be activated. ComK is required for the expression of genes encoding proteins that function in DNA uptake. In log-phase cultures, ComK is inactive in a complex with MecA and ClpC. The comS gene is induced in response to high culture cell density and nutritional stress and its product functions to release active ComK from the complex. ComK then stimulates the transcription initiation of its own gene as well as that of the late competence operons [].This entry represents proteins encoded in the comE operon for "late competence" as characterised in B. subtilis []. It is under competence control and is required for both DNA binding to the competent cell surface, and for uptake. The presence of a cytidine/deoxycytidine deaminase domain in these proteins suggests that they may perform this activity. comE contains three open reading frames (ORF1-3) read in the forward direction, preceded by a long untranslated leader sequence and an E sigma A promoter. The comE transcript is present at a very low level during growth and at an elevated level in stationary-phase cells. Conversely, the reverse transcript is present during exponential growth and disappears during the stationary phase. ORF1 and ORF3 are predicted to be integral membrane proteins. The latter is specifically required for DNA uptake but not for binding []. | Short Name: | Competence_ComEB |
