Cloning of a Candida albicans peptide transport gene

Abstract

SUMMARY A Candida albicans peptide transport gene, CaPTR2, was cloned from a C. albicans genomic library by functional complementation of a peptide transport deficient mutant (strain ptr2-2) of Saccharomyces cerevisiae. CaPTR2 restored peptide transport to transformants as determined by uptake of radiolabelled dileucine, growth on dipeptides as sources of required amino acids, and restoration of growth inhibition by toxic peptides. Plasmid curing experiments demonstrated that the peptide transport phenotype was plasmid borne. CaPTR2 was localized to chromosome R of C. albicans by contour-clamped homologous electric field gel chromosome blots. Deletion subclones and frameshift mutagenesis were used to narrow the peptide transport complementing region to a 5:1 kb DNA fragment. DNA sequencing of the complementing region identified an ORF of 1869 bp containing an 84 nucleotide intron. The deduced amino acid sequence predicts a protein of 70 kDa consisting of 623 amino acids with 12 hydrophobic segments. A high level of identity was found between the predicted protein and peptide transport proteins of S. cerevisiae and Arabidopsis thaliana. This study represents the first steps in the genetic characterization of peptide transport in C. albicans and initiates a molecular approach for the study of drug delivery against this pathogen.

Divergence of Stp1 and Stp2 Transcription Factors in Candida albicans Places Virulence Factors Required for Proper Nutrient Acquisition under Amino Acid Control

“…We examined this possibility directly by monitoring the expression levels of a select set of genes encoding amino acid permeases and peptide transporters. The transcript levels of two amino acid permease homologs (GAP1 and GAP2) (36), the dipeptide transporter (PTR2) (6), and the oligopeptide transporter (OPT1) (35) in cells grown in SD medium supplemented with glutamine were analyzed by RT-PCR (Fig. 2B).…”

Asynchronous Cell Cycle and Asymmetric Vacuolar Inheritance in True Hyphae of Candida albicans

“…Cellular parameters, compartment lengths, branching frequencies, and VOL. 2,2003 CANDIDA VACUOLE DYNAMICS 399 numbers of compartments between the hyphal apex and the first branch were measured directly from digitized microscopic images. Cell dimensions were also calculated by using a simple video analysis system (21).…”

Membrane Topology of the Di- and Tripeptide Transport Protein ofLactococcus lactis

“…In contrast to these binding protein-dependent transport systems, the di-and tripeptide carrier DtpT of L. lactis is driven by the proton motive force and composed of a single polypeptide of 463 amino acid residues. The DtpT protein has been shown to be homologous to peptide transport proteins of Saccharomyces cereVisiae (PTR2) (Perry et al, 1994), Arabidopsis thaliana (AtPTR2A and AtPTR2B) Song et al, 1996), rabbit intestine (rbPepT1) (Fei et al, 1994), human intestine (hPepT1) , and Candida albicans (CaPTR2) (Basrai et al, 1995), as well as a nitrate transport protein of A. thaliana (AtCHL) (Tsay et al, 1993); this group of proteins has been designated the peptide transport (PTR) family (Steiner et al, 1995). Alignment of the eukaryotic proteins revealed a high number of identical and similar residues, and conserved glycosylation and phosphorylation sites, as well as a signature sequence unique to this group of proteins.…”