Appendix 1

Comparison of the predicted amino acid sequences of the Azospirillum brasilense (ab) NifE (I), NifN (II), NifX (III) and NifQ (IV) proteins with analogous gene products from Azotobacter vinelandii (av) (4), Klebsiella pneumoniae (kp) (37,38), Gluconacetobacter diazotrophicus (ad) (9), Rhodobacter capsulatus (rc) (16), Bradyrhizobium japonicum (bj) (31), Herbaspirillum seropedicae (hs) (10), Rhizobium sp (rsp) (36), and Enterobacter agglomerans (es) (35). A black background indicates conserved residues in all aligned sequences, dark grey indicates conserved residues in at least 80% of the aligned sequences, and light grey indicates conserved residues in at least 60% of the aligned sequences. Conserved cysteine residues are indicated by black dots. Multiple alignment was done using the PILEUP program, University of Wisconsin Genetics Computer Group. The alignment editing was done using the GeneDoc program and the Dayhoff PAM 250 score table (39).