Cas3p belongs to a seven-member family of capsule structure designer proteins.
The polysaccharide capsule is the main virulence factor of the basidiomycetous yeast Cryptococcus neoformans. Four genes (CAP10, CAP59, CAP60, and CAP64) essential for capsule formation have been previously identified, although their roles in the biosynthetic pathway remain unclear. A genetic and bioinformatics approach allowed the identification of six CAP64-homologous genes, named CAS3, CAS31, CAS32, CAS33, CAS34, and CAS35, in the C. neoformans genome. This gene family is apparently specific in a subclass of the basidiomycete fungi. Single as well as double deletions of these genes in all possible combinations demonstrated that none of the CAP64-homologous genes were essential for capsule formation, although the cas35Delta strains displayed a hypocapsular phenotype. The chemical structure of the glucuronomannan (GXM) produced by the CAS family deletants revealed that these genes determined the position and the linkage of the xylose and/or O-acetyl residues on the mannose backbone. Hence, these genes are all involved in assembly of the GXM structure in C. neoformans.
Moyrand
Frédérique
F
Unité de Mycologie Moléculaire, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France.
Chang
Yun C
YC
Himmelreich
Uwe
U
Kwon-Chung
Kyung J
KJ
Janbon
Guilhem
G
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry; D002240:Carbohydrate Sequence; D003001:Cloning, Molecular; D019295:Computational Biology; D003455:Cryptococcus neoformans / Q000378:metabolism*; D017931:DNA Primers / Q000737:chemistry; D016521:Electrophoresis, Gel, Pulsed-Field; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D017353:Gene Deletion; D016681:Genome, Fungal; D005838:Genotype; D008358:Mannose / Q000737:chemistry; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D010641:Phenotype; D011134:Polysaccharides / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D000911:Antibodies, Monoclonal; D017931:DNA Primers; D005656:Fungal Proteins; D011134:Polysaccharides; D008358:Mannose