The Neurospora crassa colonial temperature-sensitive 3 (cot-3) gene encodes protein elongation factor 2.
At elevated temperatures, the Neurospora crassa mutant colonial, temperature-sensitive 3 (cot-3) forms compact, highly branched colonies. Growth of the cot-3 strain under these conditions also results in the loss of the lower molecular weight (LMW) isoform of the Ser/Thr protein kinase encoded by the unlinked cot-1 gene, whose function is also involved in hyphal elongation. The unique cot-3 gene has been cloned by complementation and shown to encode translation elongation factor 2 (EF-2). As expected for a gene with a general role in protein synthesis, cot-3 mRNA is abundantly expressed throughout all asexual phases of the N. crassa life cycle. The molecular basis of the cot-3 mutation was determined to be an ATT to AAT transversion, which causes an Ile to Asn substitution at residue 278. Treatment with fusidic acid (a specific inhibitor of EF-2) inhibits hyphal elongation and induces hyperbranching in a manner which mimics the cot-3 phenotype, and also leads to a decrease in the abundance of the LMW isoform of COT1. This supports our conclusion that the mutation in cot-3 which results in abnormal hyphal elongation/branching impairs EF-2 function and confirms that the abundance of a LMW isoform of COT1 kinase is dependent on the function of this general translation factor.
Department of Plant Pathology and Microbiology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
O
O
Propheta
J
J
Vierula
P
P
Toporowski
R
R
Gorovits
O
O
Yarden
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017124:Conserved Sequence; D003470:Culture Media; D005672:Fusidic Acid / Q000494:pharmacology; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D020652:Peptide Elongation Factor 2 / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012568:Schizosaccharomyces / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013696:Temperature
D003470:Culture Media; D020652:Peptide Elongation Factor 2; D020033:Protein Isoforms; D005672:Fusidic Acid