Kang Hyun-Jung, Kim Byung-Chul, Park Eun-Hee, Ahn Kisup, Lim Chang-Jin
Division of Life Sciences, College of Natural Sciences, Kangwon National University, Chuncheon, Korea.
J Biochem Mol Biol. 2005 Sep 30;38(5):609-18. doi: 10.5483/bmbrep.2005.38.5.609.
gamma-Glutamyl transpeptidase (GGT, EC 2.3.2.2.) catalyzes the transfer of the gamma-glutamyl moiety from gamma-glutamylcontaining compounds, notably glutathione (GSH), to acceptor amino acids and peptides. A second gene (GGTII) encoding GGT was previously isolated and characterized from the fission yeast Schizosaccharomyces pombe. In the present work, the GGTII-lacZ fusion gene was constructed and used to study the transcriptional regulation of the S. pombe GGTII gene. The synthesis of beta-galactosidase from the GGTII-lacZ fusion gene was significantly enhanced by NO-generating SNP and hydrogen peroxide in the wildtype yeast cells. The GGTII mRNA level was increased in the wild-type S. pombe cells treated with SNP. However, the induction by SNP was abolished in the Pap1-negative S. pombe cells, implying that the induction by SNP of GGTII is mediated by Pap1. Fermentable carbon sources, such as glucose (at low concentrations), lactose and sucrose, as a sole carbon source, enhanced the synthesis of beta-galactosidase from the GGTII-lacZ fusion gene in wildtype KP1 cells but not in Pap1-negative cells. Glycerol, a non-fermentable carbon source, was also able to induce the synthesis of beta-galactosidase from the fusion gene, but other non-fermentable carbon sources such as acetate and ethanol were not. Transcriptional induction of the GGTII gene by fermentable carbon sources was also confirmed by increased GGTII mRNA levels in the yeast cells grown with them. Nitrogen starvation was also able to induce the synthesis of beta-galactosidase from the GGTII-lacZ fusiongene in a Pap1-dependent manner. On the basis of the results, it is concluded that the S. pombe GGTII gene is regulated by oxidative and metabolic stress.
γ-谷氨酰转肽酶（GGT，EC 2.3.2.2.）催化γ-谷氨酰基从含γ-谷氨酰的化合物（尤其是谷胱甘肽，GSH）转移至受体氨基酸和肽。先前已从裂殖酵母粟酒裂殖酵母中分离并鉴定出编码GGT的第二个基因（GGTII）。在本研究中，构建了GGTII-lacZ融合基因并用于研究粟酒裂殖酵母GGTII基因的转录调控。在野生型酵母细胞中，产生NO的SNP和过氧化氢可显著增强GGTII-lacZ融合基因合成β-半乳糖苷酶的能力。用SNP处理的野生型粟酒裂殖酵母细胞中GGTII mRNA水平升高。然而，在Pap1阴性的粟酒裂殖酵母细胞中，SNP的诱导作用消失，这意味着SNP对GGTII的诱导作用是由Pap1介导的。可发酵碳源，如葡萄糖（低浓度时）、乳糖和蔗糖作为唯一碳源时，可增强野生型KP1细胞中GGTII-lacZ融合基因合成β-半乳糖苷酶的能力，但在Pap1阴性细胞中则不然。非发酵碳源甘油也能够诱导融合基因合成β-半乳糖苷酶，但其他非发酵碳源如乙酸盐和乙醇则不能。在用可发酵碳源培养的酵母细胞中，GGTII mRNA水平升高也证实了可发酵碳源对GGTII基因的转录诱导作用。氮饥饿也能够以Pap1依赖的方式诱导GGTII-lacZ融合基因合成β-半乳糖苷酶。根据这些结果，得出结论：粟酒裂殖酵母GGTII基因受氧化应激和代谢应激调控。
