Cfrench:hemanalysis1

Analysis of short chain bacteriohemerythrins

Beta Proteobacteria

Most of the beta-proteobacterial bacteriohemerythrin sequences recovered in our searches are from the genera Bordetella (family Alcaligenaceae), Burkholderia and Ralstonia (family Burkholderiaceae), Acidovorax, Comamonas, Polaromonas and Verminephrobacter (family Comamonadaceae) and Janthinobacterium (family Oxalobacteraceae) within the order Burkholderiales. Species in this group seem to have typically 1, or occasionally 2 to 4, short chain bacteriohemerythrins, but no multi-domain bacteriohemerythrins. The exception to this rule is the anoxygenic photosynthetic genus Rhodoferax, of which two sequenced genomes each appear to contain two long-chain (multi-domain) bacteriohemerythrins. Multi-domain hemerythrins also occur in anoxygenic photosynthetic "purple" bacteria in the Alpha Proteobacteria, such as Rhodopseudomonas and Rhodospirillum. Also within the Beta Proteobacteria is one of the most bacteriohemerythrin-rich non-magnetic bacteria known, Dechloromonas aromatica (order Rhodocyclales), which appears to possess at least ten putative bacteriohemerythrin genes, at least two being large multi-domain proteins and eight short chain bacteriohemerythrins.

Our initial analysis showed that the unique short-chain hemerythrins found in Burkholderia mallei (9 strains), Burkholderia pseudomallei (10 strains) and Burkholderia thailandensis are almost identical, varying only in the humber of repeats (1 to 3) of a four amino acid sequence (PELK) near the N-terminus. These are also very similar to the single putative bacteriohemerythrins found in Ralstonia eutropha (2 strains), Ralstonia solanacearum (2 strains) and Ralstonia metallidurans and to the single putative bacteriohemerythrin of Acidovorax avenae and one of the two from Acidovorax sp. JS42 (Acijs168), one of the three from Polaromonas naphthalenivorans (Polna168), and one of the four from Comamonas testosteroni (Comte165b). The three from Burkholderia xenovorans and the single one from Burkholderia vietnamensis, as well as the other one from Acidovorax sp. JS42, other two from P. naphthalenivorans, and other three from C. testosteroni do not seem to be specifically related to this clade; however, the B. vietnamensis sequence is closely related to one of the B. xenovorans sequences (Burxe165). The sequence from Janthinobacterium sp. is extremely similar to a plasmid-encoded sequence from Pseudomonas resinovorans, so closely that it seems most likely that P. resinovorans acquired the plasmid from Janthinobacterium sp. Other relationships between these sequences are not clear.