Biochemistry Institute, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
Structure. 2012 Nov 7;20(11):1850-60. doi: 10.1016/j.str.2012.07.017. Epub 2012 Sep 12.
The β-aminopeptidase BapA from Sphingosinicella xenopeptidilytica belongs to the N-terminal nucleophile (Ntn) hydrolases of the DmpA-like family and has the unprecedented property of cleaving N-terminal β-amino acid residues from peptides. We determined the crystal structures of the native (αβ)₄ heterooctamer and of the 153 kDa precursor homotetramer at a resolution of 1.45 and 1.8 Å, respectively. These structures together with mutational analyses strongly support mechanisms for autoproteolysis and catalysis that involve residues Ser250, Ser288, and Glu290. The autoproteolytic mechanism is different from the one so far described for Ntn hydrolases. The structures together with functional data also provide insight into the discriminating features of the active site cleft that determine substrate specificity.
来自 Xenopeptidilytica 属的β-氨基肽酶 BapA 属于 DmpA 样家族的 N 端亲核 (Ntn) 水解酶，具有前所未有的从肽中切割 N 端β-氨基酸残基的特性。我们分别以 1.45 和 1.8 Å 的分辨率确定了天然（αβ）₄ 异源八聚体和 153 kDa 前体同源四聚体的晶体结构。这些结构以及突变分析强烈支持涉及残基 Ser250、Ser288 和 Glu290 的自蛋白水解和催化机制。自蛋白水解机制与迄今为止描述的 Ntn 水解酶不同。这些结构以及功能数据还深入了解了决定底物特异性的活性位点裂缝的区分特征。
