Crystal structure and mechanism of tripeptidyl activity of prolyl tripeptidyl aminopeptidase from Porphyromonas gingivalis
Crystal structure and mechanism of tripeptidyl activity of prolyl tripeptidyl aminopeptidase from Porphyromonas gingivalis
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DOI：
10.1016/j.jmb.2006.06.083
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发表时间：
2006-09-15
影响因子：
5.6
通讯作者：
Yoshimoto, Tadashi
中科院分区：
文献类型：
--
作者：
Ito, Kiyoshi;Nakajima, Yoshitaka;Yoshimoto, Tadashi
测定了牙龈卟啉单胞菌的脯氨酰三肽氨基肽酶的晶体结构。脯氨酰三肽基氨基肽酶由β-推进区和催化结构域组成，结构域之间有一个很大的空腔，结构类似于二肽基氨基肽酶IV。催化结构域中有一个催化三联体(Ser603、His710和Asp678)，这个三联体与属于Pro基寡肽酶家族的酶几乎完全相同。还测定了与底物络合的失活S603A突变酶的结构。Pro残基的吡咯烷环似乎适合于由Tyr604、Va1629、Trp632、Tyr635、Tyr639、Val680和Va1681组成的疏水口袋。β-螺旋体结构域残基存在特征性差异，这些差异与三肽活性的底物专一性有关。N-末端的氨基被盐桥识别，在二肽基氨基肽酶IV的螺旋上有两个羧基Glu205和Glu206。然而，在Pro三肽氨基肽酶中，发现Glu205和Glu636执行这一功能。环结构提供了足够的空间来容纳底物的三个N-末端残基(Xaa-Xaa-Pro)。这是首次报道三肽基肽酶的结构和底物识别机制。
The crystal structure of prolyl tripeptidyl aminopeptidase from Porphyromonas gingivalis was determined. Prolyl tripeptidyl aminopeptidase consists of beta-propeller and catalytic domains, and a large cavity between the domains; this structure is similar to dipeptidyl aminopeptidase IV. A catalytic triad (Ser603, His710, and Asp678) was located in the catalytic domain; this triad was virtually identical to that of the enzymes belonging to the prolyl oligopeptidase family. The structure of an inactive S603A mutant enzyme complexed with a substrate was also determined. The pyrrolidine ring of the proline residue appeared to fit into a hydrophobic pocket composed of Tyr604, Va1629, Trp632, Tyr635, Tyr639, Val680, and Va1681. There were characteristic differences in the residues of the beta-propeller domain, and these differences were related to the substrate specificity of tripeptidyl activity. The N-terminal amino group was recognized by salt bridges, with two carboxyl groups of Glu205 and Glu206 from a helix in dipeptidyl aminopeptidase IV. In prolyl tripeptidyl aminopeptidase, however, the Glu205 (located in the loop) and Glu636 were found to carry out this function. The loop structure provides sufficient space to accommodate three N-terminal residues (Xaa-Xaa-Pro) of substrates. This is the first report of the structure and substrate recognition mechanism of tripeptidyl peptidase.