Competence protein ComEA, helix-hairpin-helix domain (IPR004509)

Short name: Competence_ComEA_HhH

Overlapping homologous superfamilies

Domain relationships



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 [PMID: 8901420].

The development of genetic competence in Bacillus subtilis is 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 [PMID: 10361283].

This domain is found in competence protein ComEA and closely related proteins from a number of species that exhibit competence for transformation by exongenous DNA, including Streptococcus pneumoniae, Bacillus subtilis, Neisseria meningitidis, and Haemophilus influenzae. This domain represents a region of two tandem copies of a helix-hairpin-helix domain, each about 30 residues in length. Limited sequence similarity can be found among some members of this family N-terminal to this domain.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.