Nagayama Ai, Kato Chiaki, Abe Fumiyoshi
Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
Extremophiles. 2004 Apr;8(2):143-9. doi: 10.1007/s00792-003-0373-0. Epub 2004 Jan 22.
Tryptophan uptake appears to be the limiting factor in growth of tryptophan auxotrophic Saccharomyces cerevisiae strains under the conditions of high hydrostatic pressure and low temperature. When the cells are subjected to a pressure of 25 MPa, tryptophan permease Tat2 is degraded in a manner dependent on ubiquitination by Rsp5. One of the high-pressure growth-conferring genes, HPG2, was shown to be allelic to TAT2. The HPG2-1 (Tat2(E27F)) mutation site is located within the ExKS motif in the N-terminus, and the HPG2-2 (Tat2(D563N)) and HPG2-3 (Tat2(E570K)) mutation sites are located at the KQEIAE sequence in the C-terminus. The HPG2 mutations enhance the stability of Tat2 during high-pressure or low-temperature incubation, leading to cell growth under these stressful conditions. These results suggest that the cytoplasmic tails are involved in Rsp5-mediated ubiquitination of Tat2 under high-pressure or low-temperature conditions.
在高静水压和低温条件下，色氨酸摄取似乎是色氨酸营养缺陷型酿酒酵母菌株生长的限制因素。当细胞受到25兆帕的压力时，色氨酸通透酶Tat2会以依赖于Rsp5泛素化的方式降解。其中一个赋予高压生长能力的基因HPG2被证明与TAT2等位。HPG2 - 1（Tat2(E27F)）突变位点位于N端的ExKS基序内，而HPG2 - 2（Tat2(D563N)）和HPG2 - 3（Tat2(E570K)）突变位点位于C端的KQEIAE序列处。HPG2突变增强了Tat2在高压或低温孵育期间的稳定性，从而导致细胞在这些应激条件下生长。这些结果表明，在高压或低温条件下，细胞质尾巴参与了Rsp5介导的Tat2泛素化过程。
