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A Ser/Thr-rich multicopy suppressor of a cdc24 bud emergence defect
1Department of Biology, University of Michigan, Ann Arbor 48109-1048.
Abstract:
MSB2 was identified previously as a multicopy suppressor of a temperature-sensitive mutation in CDC24, a gene required for polarity establishment and bud formation in Saccharomyces cerevisiae. The inferred MSB2 product contains 1306 amino acids, 42% of which are Ser or Thr. Its Ser+Thr-richness and hydrophobicity profile suggest that Msb2p may be an integral membrane protein containing a long, periplasmic, N-terminal domain and a short, cytoplasmic, C-terminal domain. Cells that lack MSB2 display no obvious mutant phenotypes. MSB2 is located between the centromere and KSS1 on the right arm of chromosome VII. Although physical mapping suggests that MSB2 and LEU1 (on the left arm of chromosome VII) are approximately 40 kb apart, the genetic map distance observed between leu1 and an msb2::URA3 marker was only 2.3 cM.
Insights
The gene MSB2 was identified as a suppressor of CDC24 mutations in yeast. Deletion of MSB2 in Saccharomyces cerevisiae showed no obvious mutant phenotypes, suggesting a complex role in cell polarity.
Area of Science:
- * Molecular and Cellular Biology
- * Yeast Genetics
- * Cell Polarity Research
Background:
- * The gene CDC24 is essential for polarity establishment and bud formation in Saccharomyces cerevisiae.
- * MSB2 was previously identified as a multicopy suppressor of a temperature-sensitive CDC24 mutation.
- * The function of MSB2 in yeast cell biology remains largely uncharacterized.
Purpose of the Study:
- * To characterize the MSB2 gene and its product in Saccharomyces cerevisiae.
- * To investigate the potential role of Msb2p in cellular processes, particularly cell polarity.
Main Methods:
- * Bioinformatic analysis of the inferred MSB2 gene product (Msb2p) sequence.
- * Construction and phenotypic analysis of MSB2 deletion mutants in yeast.
- * Genetic mapping of the MSB2 locus on chromosome VII.
Main Results:
- * The inferred Msb2p is a large protein (1306 amino acids) rich in Serine and Threonine, suggesting it may be an integral membrane protein.
- * Saccharomyces cerevisiae cells lacking MSB2 exhibit no discernible mutant phenotypes.
- * MSB2 was physically mapped to chromosome VII, with genetic mapping indicating a distance of 2.3 cM from the LEU1 locus.
Conclusions:
- * Despite its identification as a suppressor, MSB2 deletion does not cause obvious defects in yeast.
- * The predicted structure of Msb2p suggests a membrane-associated role, potentially in signaling or regulation.
- * Further studies are needed to elucidate the precise function of MSB2 in yeast cell biology.