title: Cloning and characterization of a gene (LIP1) which encodes a lipase from the pathogenic yeast Candida albicans.
abstract: Extracellular phospholipases are demonstrated virulence factors for a number of pathogenic microbes. The opportunistic pathogen Candida albicans is known to secrete phospholipases and these have been correlated with strain virulence. In an attempt to clone C. albicans genes encoding secreted phospholipases, Saccharomyces cerevisiae was transformed with a C. albicans genomic library and screened for lipolytic activity on egg-yolk agar plates, a traditional screen for phospholipase activity. Two identical clones were obtained which exhibited lipolytic activity. Nucleotide sequence analysis identified an ORF encoding a protein of 351 amino acid residues. Although no extensive homologies were identified, the sequence contained the Gly-X-Ser-X-Gly motif found in prokaryotic and eukaryotic lipases, suggesting a similar activity for the encoded protein. Indeed, culture supernatants from complemented yeast cells contained abundant hydrolytic activity against a triglyceride substrate and had no phospholipase activity. The data suggest that C. albicans, in addition to phospholipases, also has lipases. Southern blot analyses revealed that C. albicans may contain a lipase gene (LIP) family, and that a lipase gene(s) may be present in Candida parapsilosis, Candida tropicalis and Candida krusei, but not in Candida pseudotropicalis, Candida glabrata or S. cerevisiae. Northern blot analyses showed that expression of the LIP1 transcript, the cloned gene which encodes a lipase, was detected only when C. albicans was grown in media containing Tween 80, other Tweens or triglycerides as the sole carbon source, and not in Sabouraud Dextrose Broth or yeast/peptone/dextrose media. Additionally, carbohydrate supplementation inhibited LIP1 expression. Cloning this gene will allow the construction of LIP1-deficient null mutants which will be critical in determining the role of this gene in candidal virulence.
authors.affiliation: Division of Infectious Diseases, St John's Cardiovascular Research Center, Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA 90509, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Division of Infectious Diseases, St John's Cardiovascular Research Center, Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA 90509, USA.
authors.forename: Ashraf S
authors.initials: AS
authors.lastname: Ibrahim
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Georgetown University Medical Center, Washington, DC 20007-2197, USA.
authors.forename: William
authors.initials: W
authors.lastname: Fonzi
authors.affiliation: Division of Infectious Diseases, St John's Cardiovascular Research Center, Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA 90509, USA.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Division of Infectious Diseases, St John's Cardiovascular Research Center, Department of Medicine, Harbour-UCLA Medical Center, Torrance, CA 90509, USA.
authors.forename: Clarisa F
authors.initials: CF
authors.lastname: Ramos
authors.affiliation: University Center for Medical Mycology, and Mycology Reference Laboratory, Department of Dermatology, Case Western Reserve University and University Hospitals of Cleveland, 11100 Euclid Avenue, Stop LKS 5028, Cleveland, OH 44106-5028, USA.
authors.forename: Mahmoud A
authors.initials: MA
authors.lastname: Ghannoum
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002176:Candida albicans / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity; D003001:Cloning, Molecular; D004530:Egg Yolk / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics*; D018628:Gene Dosage; D015870:Gene Expression; D005800:Genes, Fungal; D008049:Lipase / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013379:Substrate Specificity
chemical_list: D005656:Fungal Proteins; D008049:Lipase