A large gene cluster encoding several magnetosome proteins is conserved indifferent species of magnetotactic bacteria

In magnetotactic bacteria, a number of specific proteins are associated wit h the magnetosome membrane (MM) and may have a crucial role in magnetite bi omineralization. We have cloned and sequenced the genes of several of these polypeptides in the magnetotactic bacterium Magnetospirillum gryphiswalden se that could be assigned to two different genomic regions. Except for mamA , none of these genes have been previously reported to be related to magnet osome formation. Homologous genes were found in the genome sequences of M. magnetotacticum and magnetic coccus strain MC-1. The MM proteins identified display homology to tetratricopeptide repeat proteins (MamA), cation diffu sion facilitators (MamB), and HtrA-like serine proteases (MamE) or bear no similarity to known proteins (MamC and MamD). A major gene cluster containi ng several magnetosome genes (including mamA and mamB) was found to be cons erved in all three of the strains investigated. The mamAB cluster also cont ains additional genes that have no known homologs in any nonmagnetic organi sm, suggesting a specific role in magnetosome formation.