NHases in Roseobacter

On the "Small Things Considered" blog (run by Prof Moselio Schaechter for the American Society for Microbiology), they have started an occasional series on interesting taxonomic groups of bacteria. The first that Prof Schaechter is giving is a pen picture of Roseobacter.

This group of bacteria are marine in origin, “make up 25% of the bacterial biomass in some coastal marine waters from the tropics to the poles” and have quite a lot of diversity in their microbiology so it seemed natural to see how much diversity there is in the recorded genomes for Roseobacter.

I did a search for nitrile hydratase alpha chains in organisms explicitly labelled as Roseobacter, and there are 7 which have RefSeq levels of quality in the NCBI database. There are two from Roseobacter litoralis Och 149, one from Roseobacter denitrificans OCh 114 and four from species various labelled sp. AZwk-3b, sp. CCS2, sp. SK209-2-6 and sp. MED193.  The two from Och 149 are very different but it can be seen from the COBALT alignment shown below that they are all cobalt containing NHases. According to a Clustal2.1 alignment, no two sequences are more than 88% similar (the second and third sequences are most similar, with the sixth/seventh pair next) with the average similarity being approximately 55%.