Figure 6.

Similarity based grouping of NadE orthologues identified in the PII-NadE genomic islands. All the NadE sequences retrieved from the identified PII-NadE islands were compared using all-against-all BLAST searches using CLANS. Each protein sequence is displayed as a dot and the pairwise similarities are presented in a graph according to the similarity distances. Three major clusters were formed. The sequences of previously characterized dimeric and octameric glutamine-dependent NadE were included as function group guide in the analysis and are indicated. The green cluster included the octameric NadE1^Gln from Mycobacterium tuberculosis, NadE1^Gln from Herbaspirillum seropedicae (HsNadE1), and NadE1^Gln from Azospirillum brasilense (AbNadE1). The blue cluster included the dimeric glutamine-dependent NadE enzymes from H. seropedicae (HsNadE2), NadE2^Gln from A. brasilense (AbNadE2), NadE^Gln from Burkholderia thailandensis, and Synechocystis sp. (ScNadE2). The red cluster includes NadE sequences lacking the N-terminal glutaminase domain and thus were considered putative ammonia-dependent NadE.