Competence operon G protein 7, ComGG (IPR020372)

Short name: Competence_ComGG

Overlapping homologous superfamilies


Family relationships



This entry represents comG operon protein 7, ComGG. It is required for DNA-binding during transformation of competent bacterial cells [PMID: 9422590]. About half of pre-ComGG is present as a peripheral membrane protein and the other half as an integral protein. Upon partial processing, ComGG is translocated to a position outside the membrane [PMID: 9723928].

The comG operon of Bacillus subtilis encodes seven membrane associated proteins which function in binding of transforming DNA to the competent cell surface [PMID: 9723928]. ComGC, GD, GE and GG have N-terminal sequence motifs typical of type 4 pre-pilins and are processed by a pathway that requires the product of comC, also an essential competence gene. They form form pilin-like structures that are localised to the cytoplasmic membrane and cell wall [PMID: 9723928]. The comG operon also consist of ComGF, a small integral membrane protein, ComGA and ComGB, which are predicted to be a nucleotide binding protein and an integral membrane protein respectively [PMID: 2507524]. When strains missing each of the 7 proteins are created, they were all found to be nontransformable and failed to bind transforming DNA to the cell surface [PMID: 9422590].

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].

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