Abstract
Recombination is a fundamental mechanism for the generation of genetic variation.
Helicobacter pylori
strains have different frequencies of intragenomic recombination, arising from deletions and duplications between DNA repeat sequences, as well as intergenomic recombination, facilitated by their natural competence. We identified a gene, hp1523, that influences recombination frequencies in this highly diverse bacterium and demonstrate its importance in maintaining genomic integrity by limiting recombination events. HP1523 shows homology to RecG, an ATP-dependent helicase that in
Escherichia coli
allows repair of damaged replication forks to proceed without recourse to potentially mutagenic recombination. Cross-species studies done show that hp1523 can complement
E. coli recG
mutants in
trans
to the same extent as
E. coli recG
can, indicating that hp1523 has
recG
function. The
E. coli recG
gene only partially complements the hp1523 mutation in
H. pylori
. Unlike other
recG
homologs, hp1523 is not involved in DNA repair in
H. pylori
, although it has the ability to repair DNA when expressed in
E. coli
. Therefore, host context appears critical in defining the function of
recG
. The fact that in
E. coli recG
phenotypes are not constant in other species indicates the diverse roles for conserved recombination genes in prokaryotic evolution.