2dq6 | pdb_00002dq6
Crystal Structure of Aminopeptidase N from Escherichia coli
Structural highlights
Function[AMPN_ECOLI] Aminopeptidase N is involved in the degradation of intracellular peptides generated by protein breakdown during normal growth as well as in response to nutrient starvation. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedAminopeptidase N from Escherichia coli is a broad specificity zinc exopeptidase belonging to aminopeptidase clan MA, family M1. The structures of the ligand-free form and the enzyme-bestatin complex were determined at 1.5- and 1.6-A resolution, respectively. The enzyme is composed of four domains: an N-terminal beta-domain (Met(1)-Asp(193)), a catalytic domain (Phe(194)-Gly(444)), a middle beta-domain (Thr(445)-Trp(546)), and a C-terminal alpha-domain (Ser(547)-Ala(870)). The structure of the catalytic domain exhibits similarity to thermolysin, and a metal-binding motif (HEXXHX(18)E) is found in the domain. The zinc ion is coordinated by His(297), His(301), Glu(320), and a water molecule. The groove on the catalytic domain that contains the active site is covered by the C-terminal alpha-domain, and a large cavity is formed inside the protein. However, there exists a small hole at the center of the C-terminal alpha-domain. The N terminus of bestatin is recognized by Glu(121) and Glu(264), which are located in the N-terminal and catalytic domains, respectively. Glu(298) and Tyr(381), located near the zinc ion, are considered to be involved in peptide cleavage. A difference revealed between the ligand-free form and the enzyme-bestatin complex indicated that Met(260) functions as a cushion to accept substrates with different N-terminal residue sizes, resulting in the broad substrate specificity of this enzyme. Crystal structure of aminopeptidase N (proteobacteria alanyl aminopeptidase) from Escherichia coli and conformational change of methionine 260 involved in substrate recognition.,Ito K, Nakajima Y, Onohara Y, Takeo M, Nakashima K, Matsubara F, Ito T, Yoshimoto T J Biol Chem. 2006 Nov 3;281(44):33664-76. Epub 2006 Aug 2. PMID:16885166[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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