Bartonella grahamii as4aup

Bartonella grahamii (strain as4aup) is Gram-negative bacterium isolated from a wood mouse (Apodemus sylvaticus) in central Sweden. B. grahamii is present in several species of mice and voles and is likely to be one of the most prevalent Bartonella species in wild rodents. It is transmitted by the rodent flea and is involved in two reported cases of human disease. Through its broad host range, B. grahamii has access to a large gene pool. The rodent-associated Bartonella species have higher copy numbers of genes for putative host-adaptability factors than the related human-specific pathogens. Many of these genes are clustered and located in a highly dynamic region (HDR) of the chromosome containing many gene clusters for secretion systems. A novel gene transfer agent packages the bacterial genome, with an over-representation of the amplified DNA, in 14 kb pieces. Consequently, the HDR is extensively amplified and packaged into bacteriophage particles. This is the first observation associating the products of run-off replication with a gene transfer agent, and the first demonstration of targeted packaging of a portion of the bacterial chromosome into viral particles. The combination of these two systems promotes diversification and rapid spread of selectively favored host-adaptability genes within and among Bartonella populations, facilitating host shifts. Thus the genome sequence of B. grahamii has been sequenced to learn more about the mechanisms and selective forces driving run-off replication and the DNA content of bacteriophage particles. (Adaptated from PMID: 19578403). (EBI Integr8)