Yamaguchi M, Hatefi Y
Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037.
J Bioenerg Biomembr. 1994 Aug;26(4):435-45. doi: 10.1007/BF00762784.
Based on the amino acid sequence of the N-terminus of the soluble subunit of the Rhodospirillum rubrum nicotinamide nucleotide transhydrogenase, two oligonucleotide primers were synthesized and used to amplify the corresponding DNA segment (110 base pairs) by the polymerase chain reaction. Using this PCR product as a probe, one clone with the insert of 6.4 kbp was isolated from a genomic library of R. rubrum and sequenced. This sequence contained three open reading frames, constituting the genes nntA1, nntA2, and nntB of the R. rubrum transhydrogenase operon. The polypeptides encoded by these genes were designated alpha 1, alpha 2, and beta, respectively, and are considered to be the subunits of the R. rubrum transhydrogenase. The predicted amino acid sequence of the alpha 1 subunit (384 residues; molecular weight 40276) has considerable sequence similarity to the alpha subunit of the Escherichia coli and the N-terminal 43-kDa segment of the bovine transhydrogenases. Like the latter, it has a beta alpha beta fold in the corresponding region, and the purified, soluble alpha 1 subunit cross-reacts with antibody to the bovine N-terminal 43-kDa fragment. The predicted amino acid sequence of the beta subunit of the R. rubrum transhydrogenase (464 residues; molecular weight 47808) has extensive sequence identity with the beta subunit of the E. coli and the corresponding C-terminal sequence of the bovine transhydrogenases. The chromatophores of R. rubrum contain a 48-kDa polypeptide, which cross-reacts with antibody to the C-terminal 20-kDa fragment of the bovine transhydrogenase. The predicted amino acid sequence of the alpha 2 subunit of the R. rubrum enzyme (139 residues; molecular weight 14888) has considerable sequence identity in its C-terminal half to the corresponding segments of the bovine and the alpha subunit of the E. coli transhydrogenases.
根据深红红螺菌烟酰胺核苷酸转氢酶可溶性亚基N端的氨基酸序列，合成了两条寡核苷酸引物，并用于通过聚合酶链反应扩增相应的DNA片段（110个碱基对）。以该PCR产物为探针，从深红红螺菌的基因组文库中分离出一个插入片段为6.4 kbp的克隆并进行测序。该序列包含三个开放阅读框，构成了深红红螺菌转氢酶操纵子的nntA1、nntA2和nntB基因。这些基因编码的多肽分别命名为α1、α2和β，被认为是深红红螺菌转氢酶的亚基。α1亚基的预测氨基酸序列（384个残基；分子量40276）与大肠杆菌的α亚基以及牛转氢酶的N端43-kDa片段有相当大的序列相似性。与后者一样，它在相应区域具有βαβ折叠，纯化的可溶性α1亚基与针对牛N端43-kDa片段的抗体发生交叉反应。深红红螺菌转氢酶β亚基的预测氨基酸序列（464个残基；分子量47808）与大肠杆菌的β亚基以及牛转氢酶的相应C端序列有广泛的序列同一性。深红红螺菌的载色体含有一种48-kDa的多肽，它与针对牛转氢酶C端20-kDa片段的抗体发生交叉反应。深红红螺菌酶的α2亚基的预测氨基酸序列（139个残基；分子量14888）在其C端一半与牛和大肠杆菌转氢酶α亚基的相应片段有相当大的序列同一性。
