Seghezzi W, Sanglard D, Fiechter A
Institute of Biotechnology, Swiss Federal Institute of Technology, ETH Hönggerberg, Zürich.
Gene. 1991 Sep 30;106(1):51-60. doi: 10.1016/0378-1119(91)90565-s.
A second alkane-inducible cytochrome P450-encoding gene (CYP52A2) from the yeast Candida tropicalis was sequenced and characterized. CYP52A2 is located 1 kb upstream from CYP52A1, the previously characterized P450 gene [Sanglard and Loper, Gene 76 (1989) 121-136] and shows the same orientation. Like CYP52A1, CYP52A2 is induced by growth on alkane. Both promoter regions share repeats of the sequence CATGTGAA that could be of importance for the induction of the two genes. At the amino acid level, alk2 shows an overall identity of 68.2% and an overall similarity of 81.6% to alk1. Regions of high homology between the two proteins are found in the distal and proximal heme binding sites which contain the highly conserved cysteine residue as the fifth ligand to the heme iron. However, marked differences between the two proteins exist at their N-terminal end, which includes the transmembrane domain, and at the putative substrate-binding domain. Upon expression of CYP52A2 in Saccharomyces cerevisiae, alk2 was shown to hydroxylate hexadecane, but had no hydroxylation activity towards lauric acid, whereas alk1 showed both activities. Comparative immunoblots demonstrate that neither alk1 nor alk2 expressed in S. cerevisiae corresponds to the main cytochrome P450 present in C. tropicalis when grown on alkane.
对热带假丝酵母中第二个烷烃诱导型细胞色素P450编码基因（CYP52A2）进行了测序和表征。CYP52A2位于先前表征的P450基因CYP52A1上游1 kb处[Sanglard和Loper，《基因》76 (1989) 121 - 136]，且方向相同。与CYP52A1一样，CYP52A2在烷烃上生长时被诱导。两个启动子区域都有CATGTGAA序列的重复，这可能对这两个基因的诱导很重要。在氨基酸水平上，alk2与alk1的总体一致性为68.2%，总体相似性为81.6%。在远端和近端血红素结合位点发现了两种蛋白质之间的高度同源区域，这些区域含有高度保守的半胱氨酸残基作为血红素铁的第五个配体。然而，两种蛋白质在其N末端（包括跨膜结构域）和假定的底物结合结构域存在明显差异。在酿酒酵母中表达CYP52A2后，alk2被证明能使十六烷羟基化，但对月桂酸没有羟基化活性，而alk1则具有这两种活性。比较免疫印迹表明，在酿酒酵母中表达的alk1和alk2都与在烷烃上生长的热带假丝酵母中存在的主要细胞色素P450不对应。
