Homology of the NifS family of proteins to a new class of pyridoxal phosphate-dependent enzymes.
Iterative profile sequence analysis reveals a remote homology of peroxisomal serine-pyruvate aminotransferases from mammals to the small subunit of soluble hydrogenases from cyanobacteria, an isopenicillin N epimerase, the NifS gene products from bacteria and yeast, and the phosphoserine aminotransferase family. All members of this new class whose function is known are pyridoxal phosphate-dependent enzymes, yet they have distinct catalytic activities. Upon alignment, a lysine around position 200 remains invariant and is predicted to be the pyridoxal phosphate-binding residue. Based on the detected homology, it is predicted that NifS has also a pyridoxal phosphate-dependent serine (or related) aminotransferase function associated with nitrogen economy and/or protection during nitrogen fixation.
Ouzounis
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Protein Design Group, European Molecular Biology Laboratory, Heidelberg, Germany.
Sander
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D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry*; D016208:Databases, Factual; D006801:Humans; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000235:genetics; D011732:Pyridoxal Phosphate / Q000502:physiology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D000637:Transaminases / Q000737:chemistry / Q000145:classification*
D001426:Bacterial Proteins; C080001:nifS protein, Bacteria; D011732:Pyridoxal Phosphate; D000637:Transaminases; C022638:serine-pyruvate aminotransferase