Cold-sensitive cell-division-cycle mutants of yeast: isolation, properties, and pseudoreversion studies

Area of Science:

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

Background:

• * The cell cycle is a fundamental process involving precise regulation of cell division.
• * Cold-sensitive (cs) mutants are valuable tools for studying essential genes, including those involved in the cell cycle.
• * Understanding cell division cycle (cdc) genes is crucial for comprehending cell proliferation and development.

Purpose of the Study:

• * To isolate and characterize new cold-sensitive cell-division-cycle (cdc) mutants in Saccharomyces cerevisiae.
• * To identify novel cdc genes and investigate their roles in cell division.
• * To explore interactions between cdc gene products and their potential assembly into functional complexes.

Main Methods:

• * Isolation and complementation analysis of 18 independent recessive cold-sensitive cdc mutants.
• * Screening for spontaneous revertants with temperature-sensitive phenotypes (Sup/Ts mutations).
• * Phenotypic analysis of mutants and revertants at restrictive temperatures to determine terminal phenotypes.

Main Results:

• * Identified 18 cs cdc mutants falling into nine complementation groups, defining at least six new cdc genes (CDC44-CDC51).
• * Discovered a novel terminal phenotype: cells with a single small bud and an undivided nucleus.
• * Isolated Sup/Ts mutations defining two new cdc genes (CDC46, CDC47) and identified alleles of CDC32, CDC11, CDC46, and CDC47, revealing complex interactions.

Conclusions:

• * The study identified novel cell division cycle genes and provided insights into their functions.
• * Evidence suggests that cdc gene products interact and may function within specific protein assemblies.
• * These findings contribute to a deeper understanding of the intricate mechanisms governing cell cycle progression in yeast.