Molecular Characterization and Analysis of the acrB Gene of Aspergillus nidulans: A Gene Identified by Genetic Interaction As a Component of the Regulatory Network That Includes the CreB Deubiquitination Enzyme

Corresponding author: Joan M. Kelly, Molecular Life Sciences Building, University of Adelaide, North Terrace, Adelaide, 5005, SA, Australia., joan.kelly{at}adelaide.edu.au (E-mail)

Communicating editor: M. S. SACHS

Mutations in the acrB gene, which were originally selected through their resistance to acriflavine, also result in reduced growth on a range of sole carbon sources, including fructose, cellobiose, raffinose, and starch, and reduced utilization of -amino acids, including GABA and ß-alanine, as sole carbon and nitrogen sources. The acrB2 mutation suppresses the phenotypic effects of mutations in the creB gene that encodes a regulatory deubiquitinating enzyme, and in the creC gene that encodes a WD40-repeat-containing protein. Thus AcrB interacts with a regulatory network controlling carbon source utilization that involves ubiquitination and deubiquitination. The acrB gene was cloned and physically analyzed, and it encodes a novel protein that contains three putative transmembrane domains and a coiled-coil region. AcrB may play a role in the ubiquitination aspect of this regulatory network.