Competence, DNA Uptake and Transformation in Pasteurellaceae
Heather Maughan, Sunita Sinha, Lindsay Wilson and Rosemary Redfield
from: Pasteurellaceae: Biology, Genomics and Molecular Aspects (Edited by: Peter Kuhnert and Henrik Christensen). Caister Academic Press, U.K. (2008)
The ability to take up DNA from the environment and recombine it into the chromosome appears to be ancestral to the Pasteurellaceae, although only some isolates do this efficiently under laboratory conditions. Studies of readily transformable isolates have shown that competence for DNA uptake is regulated by the cyclic AMP-dependent regulatory protein CRP and by Sxy, a competence-specific transcriptional activator. Once cells are competent, DNA uptake is promoted by recognition of an uptake signal sequence motif that is highly over-represented in the genomes of all Pasteurellaeae, including those that cannot be transformed. Transport of the DNA across the cell envelope uses components of the type 4 pilus machinery, homologous to those used by other naturally competent bacteria. Once in the cytoplasm this DNA may be degraded or, if sequence similarity permits, it may be recombined into the chromosome. Although such recombination can have important evolutionary consequences, DNA uptake is likely to serve primarily as a source of nucleotides for the cell read more ...