Premium
A seven‐WD40 protein related to human RACK1 regulates mating and virulence in Ustilago maydis
Author(s) -
Wang Lei,
Berndt Patrick,
Xia Xiaojuan,
Kahnt Jörg,
Kahmann Regine
Publication year - 2011
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2011.07783.x
Subject(s) - biology , ustilago , mutant , microbiology and biotechnology , genetics , fusion protein , ectopic expression , gene , recombinant dna
Summary In mammalian cells RACK1 serves as a scaffold protein that has a role in integrating inputs from different signalling pathways and affects translation through association with ribosomes. Ustilago maydis contains a seven‐WD40 repeat motif protein designated Rak1, which shows 68% identity to RACK1 and 51% identity to Asc1p of Saccharomyces cerevisiae . An asc1 mutant could be complemented by introduction of U. maydis rak1 . The deletion of rak1 affected cell growth, cell wall integrity and specifically attenuated cell fusion. This latter defect was caused by reduced expression of prf1 encoding the regulator for pheromone ( mfa ) and pheromone‐receptor genes. Rak1 interacts with a variety of ribosomal proteins and microarray analysis revealed that the deletion of rak1 led to severely reduced expression of rop1 , a transcriptional activator of prf1. The constitutive expression of rop1 could rescue the defect of mfa1 expression as well as conjugation tube formation in response to pheromone induction in the rak1 mutant. Moreover, a solopathogenic rak1 mutant failed to respond to plant‐derived stimuli, resulting in attenuated filamentation and pathogenicity. This could be partially rescued by constitutive expression of the b heterodimer. These data suggest that rak1 is a regulator of rop1 expression with additional roles after cell fusion.