Peptide specificity of protein prenyltransferases is determined mainly by reactivity rather than binding affinity
Peptide specificity of protein prenyltransferases is determined mainly by reactivity rather than binding affinity
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DOI：
10.1021/bi0509503
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发表时间：
2005-11-22
期刊：
影响因子：
2.9
通讯作者：
Fierke, CA
中科院分区：
文献类型：
--
作者：
Hartman, HL;Hicks, KA;Fierke, CA
蛋白质法尼基转移酶 (FTase) 和蛋白质香叶基香叶基转移酶 I 型 (GGTase 1) 分别催化法呢基二磷酸和香叶基香叶基二磷酸的脂质基团附着到蛋白质底物 C 末端附近的半胱氨酸上。 FTase 和 GGTase I 使用 C 端 CaaX 序列修饰几种重要的信号传导和调节蛋白（“C”指异戊二烯化的半胱氨酸残基，“a”指任何脂肪族氨基酸，“X”指任何氨基酸）。在 CaaX 范例中，蛋白质/肽的 C 端 X 残基赋予 FTase 或 GGTase I 特异性。然而，一些蛋白质，如 K-Ras、RhoB 和 TC21，是 FTase 和 GGTase 1 的底物。在这里，我们证明 C 端氨基酸影响 K-Ras4B 衍生的六肽 (TKCVIX) 与 FTase 和 GGTase I 的结合亲和力谦虚地。相反，如瞬态和稳态动力学所示，反应性变化显着，并且与 C 端氨基酸的疏水性、体积和结构相关。 FTase 的反应性随着 C 末端氨基酸的疏水性增加而降低，而 GGTase I 的反应性随着 X 基团的疏水性增加。因此，疏水性以及 X 基团的结构决定了肽是否对法尼基化、香叶基香叶基化或双异戊二烯化具有特异性。
Protein farnesyltransferase (FTase) and protein geranylgeranyltransferase type I (GGTase 1) catalyze the attachment of lipid groups from farnesyl diphosphate and geranylgeranyl diphosphate, respectively, to a cysteine near the C-terminus of protein substrates. FTase and GGTase I modify several important signaling and regulatory proteins with C-terminal CaaX sequences ("C" refers to the cysteine residue that becomes prenylated, "a" refers to any aliphatic amino acid, and "X" refers to any amino acid). In the CaaX paradigm, the C-terminal X-residue of the protein/peptide confers specificity for FTase or GGTase I. However, some proteins, such as K-Ras, RhoB, and TC21, are substrates for both FTase and GGTase 1. Here we demonstrate that the C-terminal amino acid affects the binding affinity of K-Ras4B-derived hexapeptides (TKCVIX) to FTase and GGTase I modestly. In contrast, reactivity, as indicated by transient and steady-state kinetics, varies significantly and correlates with hydrophobicity, volume, and structure of the C-terminal amino acid. The reactivity of FTase decreases as the hydrophobicity of the C-terminal amino acid increases whereas the reactivity of GGTase I increases with the hydrophobicity of the X-group. Therefore, the hydrophobicity, as well as the structure of the X-group, determines whether peptides are specific for farnesylation, geranylgeranylation, or dual prenylation.