IDENTIFICATION OF A CAP (ADENYLYL-CYCLASE-ASSOCIATED PROTEIN) HOMOLOGOUS GENE IN LENTINUS-EDODES AND ITS FUNCTIONAL COMPLEMENTATION OF YEAST CAP MUTANTS

The adenylyl-cyclase-associated protein, CAP, was originally identifie d in yeasts as a protein that functions in both signal transduction an d cytoskeletal organization. This paper reports the identification of a cDNA and genomic DNA that encodes a CAP homologue from the mushroom Lentinus edodes. The L. edodes cap gene contains eight introns and an ORF encoding a 518 amino acid protein. The L. edodes CAP is 35.5% and 40.9% identical at the amino acid level with Saccharomyces cerevisiae CAP and Schizosaccharomyces pombe CAP, respectively. The C-terminal do main shows greater homology (39-46 % identity) with yeast CAPs than do es the N-terminal domain (27-35% identity). Southern blotting and Nort hern blotting results suggest that L. edodes cap is a single-copy gene and uniformly expressed. Expression of the L. edodes CAP in both Schi z. pombe and Sacch. cerevisiae complemented defects associated with th e loss of the C-terminal domain function of the endogenous CAP. By usi ng a yeast two-hybrid assay, an interaction was demonstrated between t he L. edodes CAP and Schiz. pombe actin. This result and the functiona l complementation test indicate that CAP from L. edodes has a conserve d C-terminal domain function.