THE ASPERGILLUS-NIDULANS SEPTIN ENCODING GENE, ASPB, IS ESSENTIAL FORGROWTH

Septins are a highly conserved family of presumed cytoskeletal protein s involved in cytokinesis and morphogenesis in Saccharomyces cerevisia e and Drosophila melanogaster, To investigate the role of septins in f ilamentous fungi, we have identified presumptive septin homologues in Aspergillus nidulans, One of these septins, aspB is expressed during v egetative growth and asexual sporulation, Based on cDNA and genomic se quences, the predicted aspB protein shares a P-loop motif and coiled c oil regions with septins from other organisms, Antibodies generated ag ainst an aspB fusion protein recognized an A, nidulans protein of appr oximately 50 kDa, but could not localize the septin product in cells b y immunofluorescence. Hybridization to a chromosome-specific ordered c osmid library placed the aspB gene on the right arm of chromosome I, D isruption of aspB showed that it is an essential gene. (C) 1997 Academ ic Press.