Crystal Structure of a Membrane Stomatin-Specific Protease in Complex with a Substrate Peptide
Crystal Structure of a Membrane Stomatin-Specific Protease in Complex with a Substrate Peptide
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DOI：
10.1021/bi300098k
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发表时间：
2012-05-08
期刊：
影响因子：
2.9
通讯作者：
Fujii, Satoshi
中科院分区：
文献类型：
--
作者：
Yokoyama, Hideshi;Takizawa, Naoto;Fujii, Satoshi
膜结合蛋白酶参与各种调节功能。以前的报道表明，来自超嗜热古菌Pyrococcus horikoshii的PH 1510 p（1510-N）的N-末端区域是具有催化Ser-Lys二联体（Ser 97和Lys 138）的丝氨酸蛋白酶，并且特异性地切割p-气孔蛋白PH 1511 p的C-末端疏水区域。在人类中，缺乏气孔蛋白与一种称为遗传性气孔细胞增多症的溶血性贫血有关。在此，以2.25埃分辨率测定了与肽底物复合的1510-N K138 A的晶体结构。在该结构中，1510-N二聚体与一个肽结合。肽的六个中心残基（VIVLML）是疏水性的，并且处于假pseudopalindromic结构中，因此有利地适合1510-N二聚体的疏水活性通道，尽管1510-N仅在一个点降解底物。与未配体的1510-N K138 A的比较显示，底物的结合引起原聚体之间的大的旋转和平移位移，并产生适合于结合肽的隧道。当肽结合时，一个原聚体的柔性L2环形成β链，而另一个原聚体的柔性L2环保持环的形式，表明一个原聚体比另一个原聚体更紧密地结合肽。两个原体的Ala 138残基非常靠近（两个C β原子之间的距离为3.6埃）。因此，在野生型1510-N中，催化性Ser 97和Lys 138残基的紧密定位可以通过原聚体的两个Lys 138侧链的静电排斥来诱导。
Membrane-bound proteases are involved in various regulatory functions. A previous report indicated that the N-terminal region of PH1510p (1510-N) from the hyperthermophilic archaeon Pyrococcus horikoshii is a serine protease with a catalytic Ser-Lys dyad (Ser97 and Lys138) and specifically cleaves the C-terminal hydrophobic region of the p-stomatin PH1511p. In humans, an absence of stomatin is associated with a form of hemolytic anemia known as hereditary stomatocytosis. Here, the crystal structure of 1510-N K138A in complex with a peptide substrate was determined at 2.25 angstrom resolution. In the structure, a 1510-N dimer binds to one peptide. The six central residues (VIVLML) of the peptide are, hydrophobic and in a pseudopalindromic structure and therefore favorably fit into the hydrophobic active tunnel of the 1510-N dimer, although 1510-N degrades the substrate at only one point. A comparison with unliganded 1510-N K138A revealed that the binding of the substrate causes a large rotational and translational displacement between protomers and produces a tunnel suitable for binding the peptide. When the peptide binds, the flexible L2 loop of one protomer forms beta-strands, whereas that of the other protomer remains in a loop form, indicating that one protomer binds to the peptide more tightly than the other protomer. The Ala138 residues of the two protomers are located very close together (the distance between the two C beta atoms is 3.6 angstrom). Thus, in wild-type 1510-N, the close positioning of the catalytic Ser97 and Lys138 residues may be induced by electrostatic repulsion of the two Lys138 side chains of the protomers.