The three yeast A kinases have specific signaling functions in pseudohyphal growth

The three yeast A kinases have specific signaling functions in pseudohyphal growth

Laura S. Robertson and
Gerald R. Fink*

Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142; and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139

Contributed by Gerald R. Fink

Abstract

The three yeast A kinase catalytic subunit isoforms are redundant for viability. We demonstrate that they have dramatically different roles in pseudohyphal development: Tpk2 is essential, whereas Tpk3 inhibits. Tpk1 has no discernible effect. Two-hybrid analysis identified the transcription factor Sfl1 as a protein that interacts specifically with Tpk2, but not Tpk1 or Tpk3. Deletion of SFL1 enhances pseudohyphal and invasive growth. Flo11, a cell surface flocculin required for pseudohyphal development, is transcriptionally regulated by Tpk2 and Sfl1. Genetic evidence indicates that Tpk2 acts upstream of Sfl1 in the regulation of Flo11.

Footnotes

↵ * To whom reprint requests should be addressed. e-mail: fink{at}wi.mit.edu.
ABBREVIATIONS:

MAPK,

mitogen-activated protein kinase;

SLAD,

synthetic low ammonia dextrose