Crystallographic analysis of CaaX prenyltransferases complexed with substrates defines rules of protein substrate selectivity
Crystallographic analysis of CaaX prenyltransferases complexed with substrates defines rules of protein substrate selectivity
复制标题
DOI：
10.1016/j.jmb.2004.08.056
复制
发表时间：
2004-10-15
影响因子：
5.6
通讯作者：
Beese, LS
中科院分区：
文献类型：
--
作者：
Reid, TS;Terry, KL;Beese, LS
翻译后修饰对于细胞中许多蛋白质的正常功能至关重要。蛋白法尼基转移酶（FTase）或ⅰ型香叶基转移酶（GGTase-I）对类异戊二烯脂的附着（一种称为戊烯酰化的过程）对于许多参与生长、分化和肿瘤发生的信号转导蛋白的功能至关重要。FTase和GGTase-I（也称为CaaX戊烯基转移酶）通过c端四肽识别基序Ca(1)a(2)X盒子识别蛋白质底物。这些酶具有不同但重叠的蛋白质底物特异性，主要由Ca(1)a(2)X基序的序列一致性决定。为了确定Ca(1)a(2)X基序残基的身份及其上游序列如何影响底物结合，我们解决了FTase和GGTase-I与共8个同源和交叉反应的底物肽络合的晶体结构，包括来自癌蛋白K-Ras4B， H-Ras和TC21的C端。这些结构表明，所有肽底物在FTase和GGTase-I活性位点采用共同的结合模式。出乎意料的是，虽然Ca(1)a(2)X基序的X残基在所有GGTase-I底物的相同位置结合，但FTase底物的X残基可以在两个不同的位点之一结合。总之，这些结构勾勒出一系列支配底物肽选择性的规则；利用这些规则对已知的CaaX戊烯基转移酶的蛋白质底物进行分类，并在人类基因组中生成假设底物列表。(C) 2004 Elsevier Ltd.版权所有。
Post-translational modifications are essential for the proper function of many proteins in the cell. The attachment of an isoprenoid lipid (a process termed prenylation) by protein farnesyltransferase (FTase) or geranylgeranyltransferase type I (GGTase-I) is essential for the function of many signal transduction proteins involved in growth, differentiation, and oncogenesis. FTase and GGTase-I (also called the CaaX prenyltransferases) recognize protein substrates with a C-terminal tetrapeptide recognition motif called the Ca(1)a(2)X box. These enzymes possess distinct but overlapping protein substrate specificity that is determined primarily by the sequence identity of the Ca(1)a(2)X motif. To determine how the identity of the Ca(1)a(2)X motif residues and sequence upstream of this motif affect substrate binding, we have solved crystal structures of FTase and GGTase-I complexed with a total of eight cognate and cross-reactive substrate peptides, including those derived from the C termini of the oncoproteins K-Ras4B, H-Ras and TC21. These structures suggest that all peptide substrates adopt a common binding mode in the FTase and GGTase-I active site. Unexpectedly, while the X residue of the Ca(1)a(2)X motif binds in the same location for all GGTase-I substrates, the X residue of FTase substrates can bind in one of two different sites. Together, these structures outline a series of rules that govern substrate peptide selectivity; these rules were utilized to classify known protein substrates of CaaX prenyltransferases and to generate a list of hypothetical substrates within the human genome. (C) 2004 Elsevier Ltd. All rights reserved.