Size selection identifies new genes that regulate Saccharomyces cerevisiae cell proliferation

Area of Science:

• * Molecular and Cellular Biology
• * Yeast Genetics
• * Cell Cycle Regulation

Background:

• * Temperature-sensitive cell division cycle (cdc) mutants are crucial for studying cell cycle control.
• * Identifying genes that regulate the 'start' transition is key to understanding cell proliferation.
• * Previous studies have identified some, but likely not all, genes controlling the start transition.

Purpose of the Study:

• * To isolate and characterize novel temperature-sensitive cdc mutants in Saccharomyces cerevisiae.
• * To identify new genes regulating the critical 'start' transition of the cell cycle.
• * To investigate the roles of newly identified genes in cell proliferation and mating.

Main Methods:

• * Utilized a centrifugation procedure to enrich for enlarged yeast cells.
• * Screened for temperature-sensitive mutants exhibiting cell cycle arrest at the start transition.
• * Characterized mutant phenotypes, including proliferation, mating ability, and zygote formation.

Main Results:

• * Identified two new genes, CDC67 and CDC68, essential for the start transition.
• * Found that the previously identified gene DNA33 (termed CDC65) also harbors start mutations.
• * Observed that cdc68-1 mutants arrest proliferation but retain mating ability, while cdc65-1 and cdc67-1 mutants impair conjugation.

Conclusions:

• * The identification of CDC65, CDC67, and CDC68 expands the known genetic control of the yeast cell cycle start.
• * The novel selection procedure is effective for discovering new genes involved in cell cycle regulation.
• * The large number of genes influencing the start transition suggests complex regulatory networks in Saccharomyces cerevisiae.