J. Bahler et Jr. Pringle, POM1P, A FISSION YEAST PROTEIN-KINASE THAT PROVIDES POSITIONAL INFORMATION FOR BOTH POLARIZED GROWTH AND CYTOKINESIS, Genes & development, 12(9), 1998, pp. 1356-1370
Schizosaccharomyces pombe cells have a well-defined pattern of polariz
ed growth at the cell ends during interphase and divide symmetrically
into two equal-sized daughter cells. We identified a gene, pom1, that
provides positional information for both growth and division in S. pom
be. pom1 mutants form functioning growth zones and division septa but
show several abnormalities: (1) After division, cells initiate growth
with equal frequencies from either the old or the new end; (2) most ce
lls never switch to bipolar growth but instead grow exclusively at the
randomly chosen end; (3) some cells mislocalize their growth axis alt
ogether, leading to the formation of angled and branched cells; and (4
) many cells misplace and/or misorient their septa, leading to asymmet
ric cell division, pom1 encodes a putative protein kinase that is conc
entrated at the new cell end during interphase, at both cell ends duri
ng mitosis, and at the septation site after mitosis. Small amounts of
Pom1p are also found at the old cell end during interphase and associa
ted with the actin ring during mitosis. Pom1p localization to the cell
ends is independent of actin but requires microtubules and Tea1p. pom
1 mutations are synthetically lethal with several other mutations that
affect cytokinesis and/or the actin or microtubule cytoskeleton. Thus
, Pom1p may position the growth and cytokinesis machineries by interac
tion with both the actin and microtubule cytoskeletons.