Eukaryotic Cell doi:10.1128/EC.00269-06
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.
The WW domain protein PRO40 is required for fungal fertility and associates with Woronin bodies
Ines Engh,
Christian Würtz,
Konstanze Witzel-Schlömp,
Hai Yu Zhang,
Birgit Hoff,
Minou Nowrousian,
Hanspeter Rottensteiner,
and
Ulrich Kück*
Lehrstuhl für Allgemeine und Molekulare Botanik und Institut für Physiologische Chemie, Abteilung für Systembiochemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
* To whom correspondence should be addressed. Email:
ulrich.kueck{at}rub.de.
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Abstract |
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Fruiting body formation in ascomycetes is a highly complex process that is under polygenic control and is a fundamental part of the fungal sexual life cycle. However, the molecular determinants regulating this cellular process are largely unknown. Here we show that the sterile pro40 mutant is defective in a 120 kDa WW domain protein that plays a pivotal role in fruiting body maturation of the homothallic ascomycete Sordaria macrospora. Although WW domains occur in many eukaryotic proteins, homologs of PRO40 are present only in filamentous ascomycetes. Complementation analysis with different pro40 mutant strains using full-sized or truncated versions of the wildtype pro40 gene revealed that the C-terminus of PRO40 is crucial for restoring the fertile phenotype. Using differential centrifugation and protease protection assays, we determined that a PRO40-FLAG fusion protein is located within organelles. Further microscopic investigations of fusion proteins with DsRed or GFP polypeptides showed a co-localization of PRO40 with HEX-1, a Woronin body-specific protein. However, the integrity of Woronin bodies is not affected in mutant strains from S. macrospora and N. crassa as shown by fluorescence microscopy, sedimentation and immunoblot analyses. We discuss the function of PRO40 in fruiting body formation.
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