Covalent modification of phenylalanyl-tRNA synthetase with phenylalanine during the amino acid activation reaction catalyzed by the enzyme.
Covalent modification of phenylalanyl-tRNA synthetase with phenylalanine during the amino acid activation reaction catalyzed by the enzyme.
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DOI：
10.1016/s0021-9258(17)39260-8
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发表时间：
1985-08
期刊：
影响因子：
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通讯作者：
E. Rapaport;G. Yogeeswaran;P. Zamecnik;P. Remy
中科院分区：
文献类型：
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作者：
E. Rapaport;G. Yogeeswaran;P. Zamecnik;P. Remy
在体外氨基酸激活条件下，酵母苯丙酰trna合成酶（PRS）与苯丙氨酸发生自氨基酰化。苯丙酰腺苷酸酶复合物与α 2 β 2酶的β亚基产生共价苯丙酰异肽。与先前报道的天门冬氨酸- trna合成酶和色氨酸- trna合成酶的自氨基酰化相反，PRS的自氨基酰化发生在一组特定的条件下，结果在两种高压液相色谱柱上只鉴定出一种标记的色氨酸肽。PRS进行这种共价修饰的能力与其催化酶结合苯丙酰腺苷酸合成二腺苷5',5 ' '-P1， p4 -四磷酸的能力直接相关。这两种反应都需要低水平的锌或镉的存在，并被tRNAPhe或低水平的低分子量硫醇抑制。由于已知二腺苷5',5 ' '-P1， p4 -四磷酸的合成在体内响应氧化应激时被催化，在类似的条件下，苯丙酰trna合成酶的自氨基酰化也可能在体内发生。因此，这些反应不仅仅是苯丙酰腺苷酸积累的结果，而且可能反映了蛋白质与锌或镉相互作用所引起的构象变化。
Yeast phenylalanyl-tRNA synthetase (PRS) is shown to undergo autoaminoacylation with phenylalanine under in vitro amino acid activation conditions. Phenylalanyl adenylate enzyme complex yields a covalent phenylalanyl isopeptide exclusively with the beta subunit of the alpha 2 beta 2 enzyme. Contrary to previously reported cases of autoaminoacylation of aspartyl-tRNA synthetase and tryptophanyl-tRNA synthetase, the autoaminoacylation of PRS occurs under a specific set of conditions and results in the identification of only one labeled tryptic peptide on two types of high pressure liquid chromatography columns. The ability of PRS to undergo this covalent modification directly correlates with its ability to catalyze the synthesis of diadenosine 5',5“'-P1,P4-tetraphosphate from enzyme-bound phenylalanyl adenylate. Both reactions require the presence of low levels of zinc or cadmium and are inhibited by tRNAPhe or by low levels of low molecular weight thiols. Since diadenosine 5',5”'-P1,P4-tetraphosphate synthesis is known to be catalyzed in vivo in response to oxidation stress, it is also likely that the autoaminoacylation of phenylalanyl-tRNA synthetase may occur in vivo under a similar set of conditions. These reactions are thus not simply the result of accumulation of phenylalanyl adenylate and probably reflect conformational changes in the protein which are brought about by its interaction with zinc or cadmium.