Physical and genetic characterization of the genome of Magnetospirillum magnetotacticum, strain MS-1

Pulsed-field gel analysis of Magnetospirillum magnetotacticum, strain MS-1, indicates that the genome is a single, circular structure of about 4.3 mb. A few genes, identified by sequence similarity, have been localized and arranged in a map with dnaA, indicating the presumed origin of replication. There are at least two rRNA operons. In addition, rRNA genes are found on a 40 kb, possibly extrachromosomal, structure. The genes thought to be involved in magnetite synthesis, bfr and magA, are located in the same 17% of the genome. A one base pair-overlap seen in the bfr genes of MS-1 is found also in the closely related magnetic strain AMB-1, but not in the non-magnetic relative A.itersonii.