STRUCTURE AND ORGANIZATION OF YEAST MAL LOCI

遗传分析表明，有一个由5个未连锁的MAL基因座组成的家族 酵母，其中任何一种都足以将麦芽糖转化为葡萄糖。这个 从我们之前的研究中获得的证据表明，MAL1和MAL6 都是由至少3个基因组成的复杂基因座：麦芽糖渗透酶基因， 一个麦芽糖酶基因和一个调控基因，其产物控制坐标 麦芽糖渗透酶和麦芽糖酶的诱导。此外，Southern印迹 杂交结果表明，所有5个MAL基因座都具有序列同源性。 该提案的主旨是更详细地调查 端粒位置的组织、相关性和性质 利用重组DNA和基因技术检测MAL基因座。我们现在已经克隆了 MAL6、MAL2、MAL4和MAL1的两个非功能等位基因。科斯米德和兰布达 载体将被用来克隆剩余的MAL基因座。克隆和亚克隆 MAL基因座和相邻序列将受到限制酶， 交叉杂交和异源双链分析以研究它们之间的相关性。 这种分析还将确定集群的职能组织 不同MAL基因座的基因。在相关研究中，DNA测序 MAL6基因座的研究进展顺利。无处不在的MAL1 在许多实验室菌株中的座位(或其一个等位基因)表明它 可能是其他MAL基因座的祖先。实验将被指导 以调查MAL基因座可能是如何分散的。它的作用机制 编码转氨酶的SUC基因座的分散可能类似于 Mal基因座；Suc1似乎与MAR1相邻的位置发生了易位。这个 MAL1/Suc1这两个紧密相连的标记之间的关系将是 调查过了。 将继续进行体内和体外的密集遗传分析 产生的MAL突变体，主要在MAL1(和MAL6)基因座上，以便 饱和这两个基因座的遗传图谱。遗传的、生理的和 对这些突变体的物理分析应该特别允许我们：(1) 建立结构-职能关系；(2)提供适当的 互补性研究中的接受者；(3)帮助确定 调控蛋白及其作用位点(S)；(4)检测遗传交换 在基因座之间；和(5)帮助定义MALp和MALg函数 Naumov是Mal基因座的组成部分。遗传和生理分析 应该可以让我们确定功能和物理上的同源性程度 存在于所有5个Mal基因座中。

Genetic analysis has shown that there is a family of 5 unlinked MAL loci in yeast, any one of which is sufficient to convert maltose to glucose. The evidence obtained from our previous studies demonstrates that MAL1 and MAL6 are complex loci consisting of at least 3 genes: a maltose permease gene, a maltase gene and a regulatory gene whose product controls the coordinate induction of maltose permease and maltase. In addition, Southern blot hybridizations demonstrate that all 5 MAL loci share sequence homology. The main thrust of the proposal is to investigate in greater detail the organization, relatedness and the nature of the telomeric locations of the MAL loci using recombinant DNA and genetic techniques. We have now cloned MAL6, MAL2, MAL4 and two non-functional alleles of MAL1. Cosmid and Lambda vectors will be used to clone the remaining MAL loci. Cloned and subcloned MAL loci and adjacent sequences will be subjected to restriction enzyme, cross-hybridization and heteroduplex analyses to study their relatedness. Such analyses will also define the functional organization of the cluster of genes within the different MAL loci. In related studies, DNA sequencing of the MAL6 locus is well underway. The ubiquitous presence of the MAL1 locus (or one of its alleles) in many laboratory strains indicates that it may be the progenitor of the other MAL loci. Experiments will be directed to investigate how the MAL loci may have been dispersed. The mechanism of dispersion of the SUC loci encoding invertase may be similar to that of the MAL loci; SUC1 appears to have been transposed adjacent to mal1. The relationship of MAL1/SUC1, two very closely linked markers, will be investigated. An intensive genetic analysis will be continued on in vivo and in vitro generated Mal mutants, primarily at the MAL1 (and MAL6) loci in order to saturate the genetic map of these two loci. The genetic, physiological and physical analysis of these mutants should specifically allow us to: (1) Establish structure-function relationships; (2) provide appropriate recipients in complementation studies; (3) help to define the role of the regulatory protein and its site(s) of action; (4) examine genetic exchange between loci; and (5) help define the MALp and MALg functions designated by Naumov to be components of MAL loci. The genetic and physical analyses should allow us to determine the degree of functional and physical homology existing among all 5 MAL loci.