GENETIC INTERACTIONS BETWEEN HOP1, RED1 AND MEK1 SUGGEST THAT MEK1 REGULATES ASSEMBLY OF AXIAL ELEMENT COMPONENTS DURING MEIOSIS IN THE YEAST SACCHAROMYCES-CEREVISIAE
Nm. Hollingsworth et L. Ponte, GENETIC INTERACTIONS BETWEEN HOP1, RED1 AND MEK1 SUGGEST THAT MEK1 REGULATES ASSEMBLY OF AXIAL ELEMENT COMPONENTS DURING MEIOSIS IN THE YEAST SACCHAROMYCES-CEREVISIAE, Genetics, 147(1), 1997, pp. 33-42
During meiosis, axial elements are generated by the condensation of si
ster chromatids along a protein core as precursors to the formation of
the synaptonemal complex (SC). Functional axial elements are essentia
l for wild-type levels of recombination and proper reductional segrega
tion at meiosis I. Genetic and cytological data suggest that three mei
osis-specific genes, HOP1, RED1 and MEK1, are involved in axial elemen
t formation in the yeast Saccharomyces cerevisiae. HOP1 and RED1 encod
e structural components of axial elements while MEK1 encodes a putativ
e protein kinase. Using a partially functional allele of MEK1, new gen
etic interactions have been found between HOP1, RED1 and MEK1. Overexp
ression of HOP1 partially suppresses the spore inviability and recombi
nation defects of mek1-974; in contrast, overexpression of RED1 exacer
bates the mek1-974 spore inviability. Co-overexpression of HOP1 and RE
D1 in mek1-974 diploids alleviates the negative effect of overexpressi
ng RED1 alone. Red1p/Red1p as well as Hop1p/Red1p interactions have be
en reconstituted in two hybrid experiments. Our results suggest a mode
l whereby Mek1 kinase activity controls axial element assembly by regu
lating the affinity with which Hop1p and Red1p interact with each othe
r.