A serine and a lysine residue implicated in the catalytic mechanism of the Escherichia coli leader peptidase.
A serine and a lysine residue implicated in the catalytic mechanism of the Escherichia coli leader peptidase.
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与大肠杆菌前导肽酶的催化机制有关的丝氨酸和赖氨酸残基。
DOI：
10.1016/s0021-9258(19)74256-2
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
R. Dalbey
中科院分区：
文献类型：
--
作者：
W. Tschantz;M. Sung;V. M. Delgado;R. Dalbey
我们报道了一种硫醇前导肽酶，它是通过用半胱氨酸残基取代第90位的关键丝氨酸而产生的，具有酶活性。与野生型前导肽酶不同，硫醇酶可以被半胱氨酸特异性试剂N-乙基马来酰亚胺灭活。这有力地表明丝氨酸90参与了催化，并位于活性部位。在信号肽家族的三个保守的碱性残基中，只有赖氨酸145对催化起关键作用；当赖氨酸145突变为丙氨酸残基时，领头肽K145A蛋白在体外和体内都失去活性。对照实验表明，K145A突变体与野生型先导型多肽酶竞争底物结合，证实K145A突变不会引起全球构象变化。这些数据提供了丝氨酸-赖氨酸二聚体催化前导肽酶的证据。
We report that a thiol leader peptidase, produced by replacing the critical serine at position 90 with a cysteine residue, is enzymatically active. In contrast to the wild-type leader peptidase, the thiol enzyme can be inactivated with N-ethylmaleimide, a cysteine-specific reagent. This strongly suggests that the serine 90 is involved in catalysis and is located at the active site. Of the three conserved basic residues in the signal peptidase family, only lysine 145 appears to be critical for catalysis; when lysine 145 was mutated to an alanine residue, leader peptidase K145A protein was inactive both in vitro and in vivo. A control experiment showed that the K145A mutant competes with the wild-type leader peptidase for substrate binding, confirming that the K145A mutation did not cause a global conformational change. The data provides evidence that catalysis of leader peptidase is carried out by a serine-lysine dyad.