高山被孢霉1S-4突变体中Δ6去饱和酶基因突变位点的鉴定

Identification of mutation sites on delta6 desaturase genes from Mortierella alpina 1S-4 mutants.

作者信息

Abe Takahiro, Sakuradani Eiji, Asano Takahiro, Kanamaru Hiroyuki, Ioka Yuji, Shimizu Sakayu

机构信息

Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto.

出版信息

Biosci Biotechnol Biochem. 2005 May;69(5):1021-4. doi: 10.1271/bbb.69.1021.

DOI:10.1271/bbb.69.1021

PMID:15914925

Abstract

Three Delta6 desaturase-defective mutants, designated YB214, HR95, and ST66, were newly isolated from Mortierella alpina 1S-4, after treating wild-type spores with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). These three mutants and Mut49, isolated previously, are capable of accumulating 5,11,14-cis-eicosatrienoic acid (20:3Delta5). Two functional Delta6 desaturases (Delta6I and Delta6II) were found to exist in M. alpina 1S-4. The mutation sites on the Delta6I gene in the Delta6 desaturase-defective mutants were identified. The mutations each resulted in an amino acid replacement (W314Stop, T375K, and G390D) in Delta6I from ST66, HR95, and YB214 respectively, and uncorrected transcription of the Delta6I gene in Mut49 was caused by disappearance of the GT-terminal of the second intron, resulting in low Delta6 desaturation activity in these mutants. On the other hand, there was no mutation site on the Delta6II genes of the mutants.

摘要

在用N-甲基-N'-硝基-N-亚硝基胍（MNNG）处理野生型孢子后，从高山被孢霉1S-4中新分离出三个Δ6去饱和酶缺陷型突变体，分别命名为YB214、HR95和ST66。这三个突变体以及之前分离出的Mut49能够积累5,11,14-顺式二十碳三烯酸（20:3Δ5）。发现高山被孢霉1S-4中存在两种功能性Δ6去饱和酶（Δ6I和Δ6II）。鉴定了Δ6去饱和酶缺陷型突变体中Δ6I基因的突变位点。这些突变分别导致ST66、HR95和YB214的Δ6I中氨基酸替换（W314Stop、T375K和G390D），而Mut49中Δ6I基因的未校正转录是由第二个内含子GT末端缺失引起的，导致这些突变体中Δ6去饱和活性较低。另一方面，突变体的Δ6II基因上没有突变位点。