FIG 4.

Phylogenetic tree representation of protein sequences encoded by homologs of gmaS and representatives of the three known types of glutamine synthetase (GS). The tree was constructed by using PhyML. Organisms with experimentally characterized GMAS are in bold. Close homologs of METDI4690 are framed. For nucleotide sequence accession numbers, protein sequence lengths, and percentages of identity with M. extorquens GMAS and METDI4690, see Table S2 in the supplemental material. The accession number of each bacterium in which more than one gmaS homolog was found is shown in parentheses.