Expression of Paracoccidioides brasiliensis CHS3 in a Saccharomyces cerevisiae chs3 null mutant demonstrates its functionality as a chitin synthase gene.

We report the isolation and sequencing of CHS3, a gene that encodes one of several chitin synthases in Paracoccidioides brasiliensis, a medically important fungus restricted geographically to Latin America. The gene contains a single open reading frame of 3817 bp with two introns (71 and 86 bp) and encodes a 1220 amino acid polypeptide with high similarity to other fungal chitin synthases. Northern analysis reveals a high expression of CHS3 in the pathogenic yeast-like phase of the fungus and at the end of the mycelium yeast transition. Expression of P. brasiliensis CHS3 in a Saccharomyces cerevisiae chs3 null mutant enhanced calcofluor white staining in parallel to an increase in total chitin synthase activity and chitin content in its cell wall. The sequence of P. brasiliensis CHS3 is available at the GenBank database under Accession No. AF107623.2. Copyright (C) 2009 John Wiley & Sons, Ltd.