Evolutionary relationships of superoxide dismutases and glutamine synthetases from marine species of Alteromonas, Oceanospirillum, Pseudomonas and Deleya

Abstract

Evolutionary relationships among marine species assigned to the genera Alteromonas, Oceanospirillum, Pseudomonas, and Alcaligenes were determined by an immunological study of their Fe-containing superoxide dismutases (FeSOD) and glutamine synthetases (GS), two enzymes with differentially conserved amino acid sequences which are useful for determining intermediate and distant relationships, respectively. Five reference antisera were prepared against the FeSODs from Alteromonas macleodii, A. haloplanktis, Oceanospirillum commune, Pseudomonas stanieri, and Deleya pacifica. For GS, a previously prepared antiserum to the enzyme from Escherichia coli was employed. Amino acid sequence similarities for both enzymes were determined by the quantitative microcomplement fixation technique and the Ouchterlony double diffusion procedure. Six evolutionary groups were detected by FeSOD sequence similarities: three subgroups within the genus Alteromonas, the genera Oceanospirillum and Pseudomonas, and a new genus, Deleya (to accommodate marine Alcaligenes). Only four groupings were delineated by the GS data: the latter three genera and one group composed of all the species of Alteromonas. Evidence that all of these subgroups are derived from the evolutionary lineage defined by the purple sulfur photosynthetic bacteria is presented.