Dihydrolipoamide dehydrogenase-binding protein of the human pyruvate dehydrogenase complex - DNA-derived amino acid sequence, expression, and reconstitution of the pyruvate dehydrogenase complex
Dihydrolipoamide dehydrogenase-binding protein of the human pyruvate dehydrogenase complex - DNA-derived amino acid sequence, expression, and reconstitution of the pyruvate dehydrogenase complex
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DOI：
10.1074/jbc.272.32.19746
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发表时间：
1997-08-08
影响因子：
4.8
通讯作者：
Popov, KM
中科院分区：
文献类型：
--
作者：
Harris, RA;BowkerKinley, MM;Popov, KM
蛋白X，最近重新命名为二氢硫辛酰胺脱氢酶结合蛋白（E3 BP），是锚定二氢硫辛酰胺脱氢酶（E-3）的二氢硫辛酰胺转乙酰酶（E-2）的核心丙酮酸脱氢酶复合物的真核生物所必需的。本文报道了人丙酮酸脱氢酶复合物E3 BP的DNA和蛋白质序列。该蛋白质除了只有一个硫辛酰结构域外，具有类似于复合物E-2组分的分段多结构域结构。该蛋白的氨基端区域与E-2的第二硫辛酰结构域具有46%的氨基酸序列同一性，其中心区域与E-2的推定的外周亚基结合结构域具有38%的同一性，并且其羧基端区域与催化性内护理结构域具有50%的同一性。主要是E-2。后一结构域的相似性与酿酒酵母的E3 BP相反，酿酒酵母的E3 BP与其在该区域的同源转乙酰酶有很大不同。在人E3 BP中，存在于所有二氢硫辛酰胺酰基转移酶的内核结构域中的推定催化位点组氨酸残基被丝氨酸残基取代;因此，该蛋白质不可能催化辅酶A乙酰化，E3 BP和E-2的cDNA共表达导致ale E-2的形成。2.E3BP亚复合物，其在天然E-3和重组丙酮酸脱羧酶（E-1）存在下自发地重建丙酮酸脱氢酶复合物。
Protein X, recently renamed dihydrolipoamide dehydrogenase-binding protein (E3BP), is required for anchoring dihydrolipoamide dehydrogenase (E-3) to the dihydrolipoamide transacetylase (E-2) core of the pyruvate dehydrogenase complexes of eukaryotes. DNA and deduced protein sequences for E3BP of the human pyruvate dehydrogenase complex are reported here, With the exception of only a single lipoyl domain, the protein has a segmented multi-domain structure analogous to that of the E-2 component of the complex. The protein has 46% amino acid sequence identity in its amino-terminal region with the second lipoyl domain of E-2, 38% identity in its central region with the putative peripheral subunit-binding domain of E-2, and 50% identity in its carboxyl-terminal region with the catalytic inner care do. main of E-2. The similarity in the latter domain stands in contrast to E3BP of Saccharomyces cerevisiae, which is quite different from its homologous transacetylase in this region, The putative catalytic site histidine residue present in the inner core domains of all dihyrdrolipoamide acyltransferases is replaced by a serine residue in human E3BP; thus, catalysis of coenzyme A acetylation by this protein is unlikely, Coexpression of cDNAs for E3BP and E-2 resulted in the formation of ale E-2.E3BP subcomplex that spontaneously reconstituted the pyruvate dehydrogenase complex in the presence of native E-3 and recombinant pyruvate decarboxylase (E-1).