Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Gatersleben, Germany.
FEMS Yeast Res. 2012 Dec;12(8):924-37. doi: 10.1111/j.1567-1364.2012.00842.x. Epub 2012 Sep 14.
Fumarate reductase is an enzyme involved in maintaining redox balance through regeneration of reduced cofactors during oxygen deficiency conditions. This work reports the identification and characterization of the gene and its promoter and terminator elements that encodes cytosolic fumarate reductase enzyme in the nonconventional yeast, Arxula adeninivorans. The gene harbours an ORF of 1446 bp, encoding a 482-amino acid protein. The deduced amino acid sequence is similar to those of fumarate reductases from other yeast and fungi, such as the two fumarate reductases of Saccharomyces cerevisiae, Frd1p (44%) and Osm1p (41%). This enzyme is located in the cytosol and has a pH optimum of ca. 7.5 and a Michaelis constant (K(M)) of 2.9 mM with fumarate as the substrate. Expression of AFRD1 is regulated by the cultivation conditions. A shift from NaCl-free to NaCl-supplemented media and aerobic to hypoxic growth conditions leads to reduced AFRD1 transcription levels, but not to alteration in the concentration of Afrd1p. The functional analyses of Afrd1p were performed in A. adeninivorans and S. cerevisiae disruption mutants. The A. adeninivorans fumarate reductase is capable of functional complementation of the missing S. cerevisiae genes during anoxia; however, it is not involved in yeast growth under osmotic stress.
延胡索酸还原酶是一种在缺氧条件下通过还原辅酶的再生来维持氧化还原平衡的酶。本工作报道了非传统酵母异常毕赤酵母胞质延胡索酸还原酶基因及其启动子和终止子元件的鉴定和特征。该基因包含一个 1446bp 的 ORF，编码一个 482 个氨基酸的蛋白质。推导的氨基酸序列与其他酵母和真菌的延胡索酸还原酶相似，如酿酒酵母的两种延胡索酸还原酶 Frd1p（44%）和 Osm1p（41%）。该酶位于细胞质中，最适 pH 约为 7.5，以延胡索酸为底物时的米氏常数（K（M））为 2.9mM。AFRD1 的表达受培养条件的调节。从无 NaCl 到含 NaCl 的培养基以及从需氧到缺氧的生长条件的转变导致 AFRD1 转录水平降低，但不改变 Afrd1p 的浓度。在异常毕赤酵母和酿酒酵母缺失突变体中进行了 Afrd1p 的功能分析。异常毕赤酵母的延胡索酸还原酶能够在缺氧时对缺失的酿酒酵母基因进行功能性互补；然而，它不参与酵母在渗透压胁迫下的生长。
