title: Deletion of Candida albicans SPT6 is not lethal but results in defective hyphal growth.
abstract: As a means to study surface proteins involved in the yeast to hypha transition, human monoclonal antibody fragments (single-chain variable fragments, scFv) have been generated that bind to antigens expressed on the surface of Candida albicans yeast and/or hyphae. A cDNA expression library was constructed from hyphae, and screened for immunoreactivity with scFv5 as a means to identify its cognate antigen. A reactive clone contained the 3' end of the C. albicans gene, orf 19.7136, designated SPT6 based on homology to Saccharomyces cerevisiae, where its product functions as a transcription elongation factor. A mutant containing a homozygous deletion of SPT6 was isolated, demonstrating that unlike S. cerevisiae, deletion of this gene in C. albicans is not lethal. Growth of this strain was severely impaired, however, as was its capacity to undergo filamentous growth. Reactivity with scFv5 was not detected in the mutant strain, although its impaired growth complicates the interpretation of this finding. To assess C. albicansSPT6 function, expression of the C. albicans gene was induced in a defined S. cerevisiaespt6 mutant. Partial complementation was seen, confirming that the C. albicans and S. cerevisiae genes are functionally related in these species.
authors.affiliation: Department of Pediatrics, Women & Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Providence, RI, United States.
authors.forename: Nada
authors.initials: N
authors.lastname: Al-Rawi
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Laforce-Nesbitt
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Bliss
mesh_terms: D000595:Amino Acid Sequence; D002176:Candida albicans / Q000235:genetics* / Q000254:growth & development*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D017353:Gene Deletion; D015870:Gene Expression; D015723:Gene Library; D006801:Humans; D025301:Hyphae / Q000254:growth & development*; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D035602:Transcriptional Elongation Factors / Q000172:deficiency / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D035602:Transcriptional Elongation Factors