Complexes of mutants of Escherichia coli aminopeptidase P and the tripeptide substrate ValProLeu

Journal Article · Wed Sep 17 04:00:00 EDT 2008 · Arch. Biochem. Biophys.

DOI:https://doi.org/10.1016/j.abb.2007.10.009· OSTI ID:1006806

Graham, Stephen C; Guss, J Mitchell ^[1]

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1. Sydney

Aminopeptidase P (APPro) is a manganese-containing enzyme that catalyses the hydrolysis of the N-terminal residue of a polypeptide if the second residue is proline. Structures of APPro mutants with reduced or negligible activity have been determined in complex with the tripeptide substrate ValProLeu. In the complex of Glu383Ala APPro with ValProLeu one of the two metal sites is only partly occupied, indicating an essential role for Glu383 in metal binding in the presence of substrate. His361Ala APPro clearly possesses residual activity as the ValProLeu substrate has been cleaved in the crystals; difference electron density consistent with bound ProLeu dipeptide and a disordered Val amino acid is present at the active site. Contrary to previous suggestions, the His243Ala mutant is capable of binding substrate. The structure of the His243Ala APPro complex with ValProLeu shows that the peptide interacts with one of the active-site metal atoms via its terminal amino group. The implications of these complexes for the roles of the respective residues in APPro catalysis are discussed.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1006806
• Journal Information: Arch. Biochem. Biophys., Journal Name: Arch. Biochem. Biophys. Journal Issue: (2) ; 01, 2008 Vol. 469; ISSN ABBIA4; ISSN 0003-9861
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
AMINO ACIDS
AMINOPEPTIDASES
ATOMS
CATALYSIS
ELECTRON DENSITY
ENZYMES
ESCHERICHIA COLI
HYDROLYSIS
MUTANTS
PEPTIDES
POLYPEPTIDES
PROLINE
RESIDUES
SUBSTRATES