Amino acids induce expression of BAP2, a branched-chain amino acid permease gene in Saccharomyces cerevisiae
Amino acids induce expression of BAP2, a branched-chain amino acid permease gene in Saccharomyces cerevisiae
复制标题
DOI：
10.1128/jb.178.7.2025-2029.1996
复制
发表时间：
1996-04-01
影响因子：
3.2
通讯作者：
Andersen, HA
中科院分区：
文献类型：
--
作者：
Didion, T;Grauslund, M;Andersen, HA
酿酒酵母中支链氨基酸的摄取由至少三种转运系统介导：一般氨基酸通透酶Gap 1 p、支链氨基酸通透酶Bap 2 p和一种或多种迄今未知的通透酶。BAP 2转录的调节主要取决于培养基中某些氨基酸的存在。在以脯氨酸为唯一氮源的基本培养基上生长期间，转录水平较低。如用lacZ融合物测定的，在以铵离子作为氮源的基本培养基上转录水平略高（3倍），并且通过添加亮氨酸（0.2mM）诱导转录约20倍。低至10 μ M的亮氨酸引起5倍的诱导。另一方面，在最小脯氨酸培养基中加入L-亮氨酸对BAP 2转录没有影响。因此，两种已知的用于转运支链氨基酸的渗透酶Gap 1 p和Bap 2 p并不同时具有活性。BAP 2启动子含有一个或两个假定的Gcn 4p结合位点和一个假定的Leu 3 p结合位点，这三个位点都不需要亮氨酸诱导。亮氨酸诱导BAP 2转录伴随着支链氨基酸摄取的增加。这种升高被解释为部分是质膜中Bap 2 p通透酶水平增加的结果，因为BAP 2的缺失略微降低了摄取的诱导。仍然有亮氨酸诱导的增加，在一个三角洲缺口1三角洲bap 2菌株的支链氨基酸摄取，表明BAP 2股亮氨酸诱导至少有一个剩余的支链氨基酸转运通透酶。
Branched-chain amino acid uptake in Saccharomyces cerevisiae is mediated by at least three transport systems: the general amino acid permease Gap1p, the branched-chain amino acid permease Bap2p, and one or more so far unknown permeases. Regulation of the transcription of BAP2 is mainly subject to the presence of certain amino acids in the medium. The level of transcription is low during growth on a minimal medium with proline as the sole nitrogen source. As assayed with a lacZ fusion, the level of transcription is slightly higher (3-fold) on a minimal medium with ammonium ions as a nitrogen source, and transcription is induced about 20-fold by addition of leucine (0.2 mM). As little as 10 mu M leucine causes a fivefold induction, Addition of L-leucine to minimal proline medium, on the other hand, has no effect on BAP2 transcription. The two known permeases for transport of branched-chain amino acids, Gap1p and Bap2p, are thus not active at the same time. The BAP2 promoter contains one or two putative Gcn4p binding sites and one putative Leu3p binding site, None of the three is needed for induction by leucine. Induction of BAP2 transcription by leucine is accompanied by an increase in branched-chain amino acid uptake. This elevation is interpreted to be partly the result of an increased level of the Bap2p permease in the plasma membrane, because deletion of BAP2 slightly decreases the induction of uptake. There is still a leucine-inducible increase in branched-chain amino acid uptake in a Delta gap1 Delta bap2 strain, indicating that BAP2 shares leucine induction with at least one remaining branched-chain amino acid-transporting permease.