THE ORGANIZATION AND TRANSCRIPTION OF THE GALACTOSE GENE-CLUSTER OF SACCHAROMYCES
THE ORGANIZATION AND TRANSCRIPTION OF THE GALACTOSE GENE-CLUSTER OF SACCHAROMYCES
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DOI：
10.1016/0022-2836(81)90244-8
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发表时间：
1981-01-01
影响因子：
5.6
通讯作者：
DAVIS, RW
中科院分区：
文献类型：
--
作者：
STJOHN, TP;DAVIS, RW
以三个半乳糖诱导序列为中心的链霉菌DNA kb <$区域的转录活性已被检测。体内产生的gal 7-、gal 10-、gal 1-突变、gal 1-突变（由D. C.霍桑）是与所有三种诱导型RNA的图谱位置重叠的7 kb缺失。这三种RNA对应于位于染色体II上的GAL 7-GAL 10-GAL 1基因簇的转录物。基因分配已被推断通过比较发表的蛋白质大小和实验确定的信使RNA长度。GAL 7和GAL 10基因（分别编码半乳糖-1-磷酸尿苷酰转移酶和尿苷二磷酸半乳糖-4-差向异构酶）由同一条DNA链转录。GAL 1基因（编码半乳糖激酶）由互补DNA链转录而成，其5′端与GAL 10基因的5′端相距0.65 kb。这三个基因通常被转录成至少六个离散的RNA物种在检查的菌株。在非允许温度下，在酵母1 -1“核转运”突变体中检测到另外两个GAL 1转录物。GAL 1基因的转录导致了5个可检测的RNA分子（1.65、1.75、4.5、5.5和6.5 ~ 7 kb）的存在，其中最长的两个仅在限制性温度下的therna 1 - 1突变体中检测到。这五个转录本仅在它们的3′端不同。这些RNA的5′端通过S1核酸酶作图程序无法区分。两个最小的RNA仅比编码半乳糖激酶所需的略大。GAL 7和GAL 10基因序列存在于1.25和2.25 kb的RNA分子中。分别，并且相隔约0.65kb。这些分开的GAL 7和GAL 10 RNA仅比编码其各自蛋白质所需的长度长约200个碱基。这两个基因也一起转录成一个大的RNA分子（4.15 kb），比单独的GAL 7和GAL 10信使RNA的长度之和长0.65 kb。该分子的5′端不能与GAL 10 mRNA的5′端区分开。酵母1 - 1突变体在非允许温度下积累了3个最大的GAL 1转录本，但缺乏核转运（和/或RNA加工）功能。在此条件下，突变体1 - 1除了积累1.25kb的GAL 7 RNA外，还积累了含有GAL 7和GAL 10基因序列的大RNA。这些数据表明存在一个GAL 1基因转录的启动子，一个相邻的GAL 10和/或GAL 10和GAL 7转录的启动子，以及GAL 7基因的第三个启动子。克隆的28 kb的DNA序列延伸到基因簇之外，并且包含至少四个不太可能与GAL基因簇相关的转录区域。尽管重复的DNA序列位于克隆区域的最左边缘，但簇区域中的所有DNA本身都是独特的。
The transcriptional activity of a kb†region ofSaccharomycesDNA centered on three galactose-inducible sequences has been examined. Anin vivo-generatedgal7−,gal10−,gal1−mutation,gal▽ (isolated by D. C. Hawthorne), is a 7 kb deletion that overlaps the map positions of all three inducible RNAs. These three RNAs correspond to the transcripts of theGAL7-GAL10-GAL1gene cluster located on chromosome II. Gene assignments have been inferred by comparison of the published protein sizes and the experimentally determined messenger RNA lengths. The physically assigned gene order,GAL7-GAL10-GAL1, agrees with the genetically established order.TheGAL7andGAL10genes (which encode galactose-1-phosphate uridylyl transferase and uridine diphosphogalactose-4-epimerase, respectively) are transcribed from the same DNA strand. TheGAL1gene (which encodes galactokinase) is transcribed from the complementary DNA strand such that its 5′ end is 0.65 kb from the 5′ end of theGAL10gene. These three genes are normally transcribed into at least six discrete RNA species in the strains examined. Two additionalGAL1transcripts have been detected at the non-permissive temperature in the yeastrna1-1“nuclear transport” mutant. None of these eight transcripts contains detectable intervening sequences.Transcription of theGAL1gene results in the presence of five detectable RNA molecules (1.65, 1.75, 4.5, 5.5 and 6.5 to 7 kb), the two longest having only been detected in therna1-1mutant at the restrictive temperature. These five transcripts differ only at their 3′ ends. The 5′ ends of these RNAs are indistinguishable by S1nuclease mapping procedures. The two smallest RNAs are only slightly larger than required to encode galactokinase.GAL7 andGAL10gene sequences are found in 1.25 and 2.25 kb RNA molecules. respectively, and are separated by about 0.65 kb. These separateGAL7andGAL10RNAs arc only approximately 200 bases longer than required to encode their respective proteins. These two genes are also transcribed together into a large RNA molecule (4.15 kb), 0.65 kb longer than the sum of the lengths of the separateGAL7andGAL10messenger RNAs. The 5′ end of this molecule cannot be distinguished from the 5′ end of theGAL10mRNA. Its 3′ end is very near or identical to the 3′ end of theGAL7mRNA.The yeastrna1-1mutant, deficient in nuclear transport (and/or RNA processing), accumulates the three largestGAL1transcripts at the non-permissive temperature. Under these conditions, therna1-1mutant also accumulates the large RNA containing bothGAL7andGAL10gene sequences as well as the 1.25 kbGAL7RNA. These data suggest the presence of a promoter for the transcription of theGAL1gene, an adjacent promoter for the transcription ofGAL10and/or bothGAL10andGAL7, and a third promoter for theGAL7gene. The 28 kb of cloned DNA sequences extend beyond the gene cluster and contain at least four transcribed regions that are not likely to be related to theGALgene cluster. All of the DNA in the cluster region itself is unique, although repeated DNA sequences are located at the extreme left edge of the cloned region.