The DmpA aminopeptidase from Ochrobactrum anthropi LMG7991 is the prototype of a new terminal nucleophile hydrolase family.
The DmpA (d-aminopeptidase A) protein produced by Ochrobactrum anthropi hydrolyses p-nitroanilide derivatives of glycine and d-alanine more efficiently than that of l-alanine. When regular peptides are utilized as substrates, the enzyme behaves as an aminopeptidase with a preference for N-terminal residues in an l configuration, thus exemplifying an interesting case of stereospecificity reversal. The best-hydrolysed substrate is l-Ala-Gly-Gly, but tetra- and penta-peptides are also efficiently hydrolysed. The gene encodes a 375-residue precursor, but the active enzyme contains two polypeptides corresponding to residues 2-249 (alpha-subunit) and 250-375 (beta-subunit) of the precursor. Residues 249 and 250 are a Gly and a Ser respectively, and various substitutions performed by site-directed mutagenesis result in the production of an uncleaved and inactive protein. The N-terminal Ser residue of the beta-subunit is followed by a hydrophobic peptide, which is predicted to form a beta-strand structure. All these properties strongly suggest that DmpA is an N-terminal amidohydrolase. An exploration of the databases highlights the presence of a number of open reading frames encoding related proteins in various bacterial genomes. Thus DmpA is very probably the prototype of an original family of N-terminal hydrolases.
Fanuel
L
L
Laboratoire d'Enzymologie et Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B6, B-4000 Sart Tilman, Belgium.
Goffin
C
C
Cheggour
A
A
Devreese
B
B
Van Driessche
G
G
Joris
B
B
Van Beeumen
J
J
Frère
J M
JM
D000581:Amidohydrolases / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D004151:Dipeptides / Q000378:metabolism; D004789:Enzyme Activation; D006090:Gram-Negative Bacteria / Q000201:enzymology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009842:Oligopeptides / Q000378:metabolism; D011498:Protein Precursors / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D013379:Substrate Specificity
D001426:Bacterial Proteins; D004151:Dipeptides; D009842:Oligopeptides; D011498:Protein Precursors; D011994:Recombinant Proteins; D000626:Aminopeptidases; C118321:DmpA protein, Ochrobactrum anthropi; D000581:Amidohydrolases