Mycelial growth in filamentous fungi results from polarised growth and hyphal branching. In addition to interest in the fundamental processes controlling this form of growth, colonial morphology is important in industrial fermentations. In order investigate the genetic basis of hyphal branching and growth polarity in the genetic model A. nidulans, we are isolating genes by complementation of mutants affecting branching frequency (see poster by Memmott et al.) and by isolation of homologues of genes from yeast or filamentous fungi. The cot-1 gene of Neurospora crassa, encoding a serine-threonine protein kinase (Yarden et al. 1992, EMBO J. 11, 2159) is one of a limited number of characterised genes known to affect polar growth and branching frequency. Degenerate oligonucleotides designed against cot-1, and homologues from C trifolii and S. cerevisiae were used to amplify a fragment from A. nidulans. Sequence analysis revealed marked identity with cot-1. Using the PCR amplified fragment as a probe, 3 related cosmid clones, assigned to chromosome V, were isolated from the chromosome sorted genomic library. Although 2 were adjacent on the physical map (Prade et al. 1997, PNAS 94,14564) a third was localised elsewhere on V, suggesting mislocalisation of one or more of the cosmids. Sequence analysis of the entire gene revealed high sequence identity at in the C-terminal region, but considerable divergence in the N-terminal region of the derived protein sequence. Attempts are underway to disrupt the gene, and alter the level of expression by promoter exchange.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)