An RGRI gene product is required to repress expression of glucose-regulated genes in Saccharomyces cerevisiae. The abnormal morphology of rgrl cells was studied. Scanning and transmission electron microscopic observations revealed that the cell wail of the daughter cell remained attached to that of mother cell. We cloned the RGRI gene by complementation and showed that the cloned DNA was tightly linked to the chromosomal RGRI locus. The cloned RGRI gene suppressed all of the phenotypes caused by the mutation and encoded a 3.6-kilobase poly(A)' RNA. The RGRI gene is located on chromosome XII, as determined by pulsed-field gel electrophoresis, and we mapped rgrl between gal2 and pep3 by genetic analysis. rgrl was shown to be a new locus. We also determined the nucleotide sequence of RGRI, which was predicted to encode a 123-kilodalton protein. The null mutation resulted in lethality, indicating that the RGRI gene is essential for growth. On the other hand, a carboxy-terminal deletion of the gene caused phenotypes similar to but more severe than those caused by the original mutation. The amount of reserve carbohydrates was reduced in rgrl cells. Possible functions of the RGRI product are discussed.Glucose regulates the expression of many genes in Saccharomyces cerevisiae (for a review, see reference 5). One of them, the SUC2 gene, which encodes invertase, is repressed by glucose (2, 3). Recently, we reported the isolation of a new mutation, rgrl, which affects expression of the SUC2 gene (21). A recessive rgrl-l mutation which caused overexpression of mouse a-amylase under the control of the SUC2 promoter was isolated, and the RGRI gene was found to be required for glucose repression. The rgrl mutation affected several cellular functions. Cells were resistant to glucose repression, temperature sensitive for cell growth, and sporulation deficient and showed abnormal cell morphology. Expression of the SUC2 gene in rgrl strains was resistant to glucose repression, and SUC2 expression was increased under glucose-derepressing conditions. In this report, we describe studies of the morphology of rgrl cells, the cloning and molecular analysis of the RGRI gene, and meiotic linkage analysis of rgrl. We constructed deletion mutations to determine the phenotypes of strains lacking a functional RGRI gene product and determined the nucleotide sequence of the gene. The RGRI gene affected accumulation of reserve carbohydrates. MATERIALS AND METHODSStrains and genetic methods. The strains of S. cerevisiae used in this study are listed in Table 1. All strains were derived from S288C. Crossing, sporulation, and tetrad analysis were carried out by standard genetic methods (23). The permissive and restrictive temperatures were 24 and 37°C, respectively. The phenotype of pep3 strains was scored as described elsewhere (12). The transformation of yeast was performed by the LiOAc-method of Ito et al. (11). Escherichia coli HB101 and JM109 were employed as hosts for * Corresponding author.constructing and propagating plasmids. The transform...

An RGR1 gene product is required to repress expression of glucose-regulated genes in Saccharomyces cerevisiae. The abnormal morphology of rgr1 cells was studied. Scanning and transmission electron microscopic observations revealed that the cell wall of the daughter cell remained attached to that of mother cell. We cloned the RGR1 gene by complementation and showed that the cloned DNA was tightly linked to the chromosomal RGR1 locus. The cloned RGR1 gene suppressed all of the phenotypes caused by the mutation and encoded a 3.6-kilobase poly(A)+ RNA. The RGR1 gene is located on chromosome XII, as determined by pulsed-field gel electrophoresis, and we mapped rgr1 between gal2 and pep3 by genetic analysis. rgr1 was shown to be a new locus. We also determined the nucleotide sequence of RGR1, which was predicted to encode a 123-kilodalton protein. The null mutation resulted in lethality, indicating that the RGR1 gene is essential for growth. On the other hand, a carboxy-terminal deletion of the gene caused phenotypes similar to but more severe than those caused by the original mutation. The amount of reserve carbohydrates was reduced in rgr1 cells. Possible functions of the RGR1 product are discussed.