Heinisch J J, Müller S, Schlüter E, Jacoby J, Rodicio R
Institut fur Mikrobiologie, Heinrich-Heine-Universitat Dusseldorf, Germany.
Yeast. 1998 Feb;14(3):203-13. doi: 10.1002/(SICI)1097-0061(199802)14:3<203::AID-YEA205>3.0.CO;2-8.
Our previous data indicated that GPM1 encodes the only functional phosphoglycerate mutase in yeast. However, in the course of the yeast genome sequencing project, two homologous sequences, designated GPM2 and GPM3, were detected. They have been further investigated in this work. Key residues in the deduced amino acid sequence, shown to be involved in catalysis for Gpm1 (i.e. His8, Arg59, His181) are conserved in both enzymes. Overexpression of the genes under control of their own promoters in a gpm1 deletion mutant did not complement for any of the phenotypes. This could in part be attributed to a lack of expression due to their weak promoters. Higher level expression under the control of the yeast PFK2 promoter partially complemented the gpm1 defects, without restoring detectable enzymatic activity. Nevertheless, deletion of either GPM2 or GPM3, or the two deletions in concert, did not produce any obvious lesions for growth on a variety of different carbon sources, nor did they change the levels of key intermediary metabolites. We conclude that both genes evolved from duplication events and that they probably constitute non-functional homologues in yeast.
我们之前的数据表明，GPM1编码酵母中唯一具有功能的磷酸甘油酸变位酶。然而，在酵母基因组测序项目过程中，检测到两个同源序列，命名为GPM2和GPM3。在本研究中对它们进行了进一步研究。推导的氨基酸序列中显示参与Gpm1催化作用的关键残基（即His8、Arg59、His181）在这两种酶中均保守。在gpm1缺失突变体中，在其自身启动子控制下的基因过表达不能互补任何表型。这部分可归因于其弱启动子导致的表达缺失。在酵母PFK2启动子控制下的更高水平表达部分互补了gpm1缺陷，但未恢复可检测到的酶活性。然而，单独缺失GPM2或GPM3，或两者同时缺失，在多种不同碳源上生长均未产生任何明显损伤，也未改变关键中间代谢物的水平。我们得出结论，这两个基因均由复制事件进化而来，并且它们可能在酵母中构成无功能的同源物。
