Open AccessFunctional Characterization of the Interaction of Ste50p with Ste11p MAPKKK inSaccharomyces cerevisiae
Author(s) -
Cunle Wu,
Ekkehard Leberer,
David Y. Thomas,
Malcolm Whiteway
Publication year - 1999
Publication title -
molecular biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.463
H-Index - 225
eISSN - 1939-4586
pISSN - 1059-1524
DOI - 10.1091/mbc.10.7.2425
Subject(s) - biology , cyclin dependent kinase 7 , autophosphorylation , schizosaccharomyces pombe , microbiology and biotechnology , saccharomyces cerevisiae , map kinase kinase kinase , kinase , signal transduction , cyclin dependent kinase 1 , cyclin dependent kinase 9 , c raf , biochemistry , protein kinase domain , protein kinase a , cyclin dependent kinase complex , mitogen activated protein kinase kinase , yeast , gene , cell cycle , mutant
The Saccharomyces cerevisiae Ste11p protein kinase is a homologue of mammalian MAPK/extracellular signal-regulated protein kinase kinase kinases (MAPKKKs or MEKKs) as well as the Schizosaccharomyces pombe Byr2p kinase. Ste11p functions in several signaling pathways, including those for mating pheromone response and osmotic stress response. The Ste11p kinase has an N-terminal domain that interacts with other signaling molecules to regulate Ste11p function and direct its activity in these pathways. One of the Ste11p regulators is Ste50p, and Ste11p and Ste50p associate through their respective N-terminal domains. This interaction relieves a negative activity of the Ste11p N terminus, and removal of this negative function is required for Ste11p function in the high-osmolarity glycerol (HOG) pathway. The Ste50p/Ste11p interaction is also important (but not essential) for Ste11p function in the mating pathway; in this pathway binding of the Ste11p N terminus with both Ste50p and Ste5p is required, with the Ste5p association playing the major role in Ste11p function. In vitro, Ste50p disrupts an association between the catalytic C terminus and the regulatory N terminus of Ste11p. In addition, Ste50p appears to modulate Ste11p autophosphorylation and is itself a substrate of the Ste11p kinase. Therefore, both in vivo and in vitro data support a role for Ste50p in the regulation of Ste11p activity.