Genetic analysis of cell-cell adhesion in yeast.
Michael
J. Svarovsky, Sean P. Palecek
Chemical Engineering, University
of Wisconsin, 1415 Engineering Dr., Madison, WI 53706, USA
Recent
work has shown that adhesion regulates invasive and filamentous growth
in S. cerevisiae. Flocculins, a family of cell-surface
glycoproteins, mediate adhesion to mannans on neighboring cells. Yeast
cell wall composition and septum regulation can also affect attachment
between mother and daughter cells. We have used a filtration assay to
identify genetic mechanisms that promote cellular adhesion by regulating
these or other mechanisms. A LEU2-containing transposon cassette
was used to randomly disrupt the genome of haploid sigma-strain 1278b
S. cerevisiaecells. A vacuum was used to draw the mutagenized
pool over a polycarbonate membrane containing uniform cylindrical 20-micron diameter pores. Retained cells were collected and examined with
an optical microscope, and samples in which increased adhesion was
linked to the LEU2insertion were sequenced. Using this assay, the
mutation of LRG1was found to increase cellular adhesion. Lrg1 has
been previously characterized as a GAP for Rho1. In its GTP-bound state,
Rho1 activates 1,3-beta-glucan synthase both directly, through binding
of the Fks1/Fks2 subunits, and transcriptionally, through the activation
of PKC1. We propose that the activation of Rho1 in the absence of Lrg1
leads to additional glucan production and increased adhesion.
Return to YGM 2002 Home at SGD