title: Coccidioides posadasii contains a single 1,3-beta-glucan synthase gene that appears to be essential for growth.
abstract: 1,3-beta-Glucan synthase is responsible for the synthesis of beta-glucan, an essential cell wall structural component in most fungi. We sought to determine whether Coccidioides posadasii possesses genes homologous to known fungal FKS genes that encode the catalytic subunit of 1,3-beta-glucan synthase. A single gene, designated FKS1, was identified, and examination of its predicted protein product showed a high degree of conservation with Fks proteins from other filamentous fungi. FKS1 is expressed at similar levels in mycelia and early spherulating cultures, and expression decreases as the spherules mature. We used Agrobacterium-mediated transformation to create strains that harbor DeltaFKS1::hygB, a null allele of FKS1, and hypothesize that Fks1p function is essential, due to our inability to purify this allele away from a complementing wild-type FKS1 allele in a heterokaryotic strain. The heterokaryon appears normal with respect to growth rate and arthroconidium production; however, microscopic examination of strains with DeltaFKS1::hygB alleles revealed abnormal swelling of hyphal elements.
authors.affiliation: Valley Fever Center for Excellence, 3601 S. Sixth Ave., Tucson, AZ 85723, USA.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Kellner
authors.forename: Kris I
authors.initials: KI
authors.lastname: Orsborn
authors.forename: Erin M
authors.initials: EM
authors.lastname: Siegel
authors.forename: M Alejandra
authors.initials: MA
authors.lastname: Mandel
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Orbach
authors.forename: John N
authors.initials: JN
authors.lastname: Galgiani
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D015139:Blotting, Southern; D020134:Catalytic Domain; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival; D002473:Cell Wall / Q000378:metabolism; D002478:Cells, Cultured; D003045:Coccidioides / Q000201:enzymology* / Q000502:physiology*; D005656:Fungal Proteins / Q000378:metabolism; D017353:Gene Deletion; D015723:Gene Library; D005800:Genes, Fungal; D005964:Glucosyltransferases / Q000235:genetics* / Q000502:physiology*; D008938:Mitosis; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012231:Rhizobium / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
chemical_list: D005656:Fungal Proteins; D012313:RNA; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase