Nucleotide sequence of the exo-1,3-β-glucanase-encoding gene, EXG1, of the yeast Saccharomyces cerevisiae

Abstract The nucleotide (nt) sequence of the Saccharomyces cerevisiae gene ( EXG1 ) encoding extracellular exo-1,3-β-glucanases (EXG) I and II was determined. An open reading frame of 1344 bp codes for a 448-amino acid (aa) polypeptide, with a calculated M r of 51307, which contains two potential N -glycosylation sites. The EXG1 DNA hybridizes to a 1.7-kb transcript whose 5' end maps to a position 98 bp upstream from the site of initiation of protein synthesis. Comparison of the N-terminal aa sequence deduced from the nt sequence with that of the purified EXGII revealed the existence of an extra 40-aa peptide in the precursor protein containing a Lys-Arg peptidase-processing site at the junction with the mature, extracellular form. The N-terminal region of the putative precursor is a very hydrophobic segment with structural features resembling those of signal peptides of secreted proteins. The M c of the mature EXG polypeptide deduced from the nt sequence is 46385. The 5'- and 3' -flanking regions of the EXG1 gene have structural features in common with other yeast genes.