Levine J, Tanouye L, Michels C A
Department of Biology, Queens College, Flushing, NY 11367.
Curr Genet. 1992 Sep;22(3):181-9. doi: 10.1007/BF00351724.
Maltose fermentation in Saccharomyces yeasts requires one of five unlinked MAL loci: MAL1, 2, 3, 4, or 6. Each locus consists of three genes encoding maltose permease, maltase and the MAL activator. At MAL6 the genes are called MAL61, MAL62 and MAL63, respectively. Transcription of MAL61 and MAL62 is coordinately induced by maltose and repressed by glucose and this regulation is mediated by the MAL activator. By deletion analysis of the MAL61-MAL62 intergenic region, we show that a 68-basepair region, from base pairs -515 to -582 upstream of the MAL61 start codon, contains a sequence necessary for the maltose-induced expression of MAL61 and MAL62, the UAS(MAL). This sequence contains two copies of an 11-basepair dyad which may be the active elements of the UAS(MAL). Using heterologous gene plasmid constructs, we demonstrate that the UAS(MAL) sequence is sufficient for maltose inducibility of MAL62 and that this regulated expression requires a functional MAL activator. Our results suggest that the MAL61-MAL62 intergenic region contains additional distinct elements which function to precisely regulate MAL61 and/or MAL62 expression. Among these are repressing sequences, including a glucose-responsive element located between base pairs -583 and -638, which is partially responsible for mediating glucose-repression of MAL62 expression.
酿酒酵母中的麦芽糖发酵需要五个不连锁的MAL基因座之一：MAL1、2、3、4或6。每个基因座由三个基因组成，分别编码麦芽糖通透酶、麦芽糖酶和MAL激活剂。在MAL6基因座，这些基因分别称为MAL61、MAL62和MAL63。MAL61和MAL62的转录由麦芽糖协同诱导，并被葡萄糖抑制，这种调控由MAL激活剂介导。通过对MAL61 - MAL62基因间区域的缺失分析，我们发现，在MAL61起始密码子上游-515至-582碱基对的一个68碱基对区域，包含麦芽糖诱导MAL61和MAL62表达所必需的序列，即UAS(MAL)。该序列包含两个11碱基对的二元体拷贝，可能是UAS(MAL)的活性元件。使用异源基因质粒构建体，我们证明UAS(MAL)序列足以使MAL62具有麦芽糖诱导性，并且这种调控表达需要功能性的MAL激活剂。我们的结果表明，MAL61 - MAL62基因间区域包含其他不同的元件，其功能是精确调节MAL61和/或MAL62的表达。其中包括抑制序列，包括位于-583至-638碱基对之间的葡萄糖反应元件，它部分负责介导葡萄糖对MAL62表达的抑制。
