Yeast Kre1p is a cell surface O-glycoprotein

Area of Science:

• * Molecular and Cellular Biology
• * Mycology
• * Biochemistry

Background:

• * The KRE1 gene in Saccharomyces cerevisiae encodes a secretory protein essential for synthesizing the cell wall polymer (1-->6)-beta-glucan.
• * Understanding Kre1p's function and modifications is key to deciphering yeast cell wall assembly and integrity.

Purpose of the Study:

• * To further characterize the KRE1 gene product, Kre1p, focusing on its post-translational modifications, localization, and function.
• * To investigate the cellular processes influencing Kre1p's modification and its role in cell wall structure.

Main Methods:

• * Functional epitope-tagged Kre1p expression and analysis.
• * Cellular fractionation to isolate different Kre1p species.
• * Indirect immunofluorescence microscopy for localization studies.

Main Results:

• * Functional Kre1p undergoes significant post-translational modification, dependent on SEC53, including O-glycosylation.
• * Kre1p exists in both cell wall-associated and membrane-associated forms.
• * Kre1p localizes to the cell surface, concentrating on mother cells, similar to chitin deposition patterns.

Conclusions:

• * Kre1p is a highly modified protein involved in (1-->6)-beta-glucan production and cell wall integrity in Saccharomyces cerevisiae.
• * Its cell surface localization and association with cell wall components suggest a direct role in cell wall construction and maturation.