Histatin 5 uptake by Candida albicans utilizes polyamine transporters Dur3 and Dur31 proteins.
Histatin 5 (Hst 5) is a salivary gland-secreted cationic peptide with potent fungicidal activity against Candida albicans. Hst 5 kills fungal cells following intracellular translocation, although its selective transport mechanism is unknown. C. albicans cells grown in the presence of polyamines were resistant to Hst 5 due to reduced intracellular uptake, suggesting that this cationic peptide may enter candidal cells through native yeast polyamine transporters. Based upon homology to known Saccharomyces cerevisiae polyamine permeases, we identified six C. albicans Dur polyamine transporter family members and propose a new nomenclature. Gene deletion mutants were constructed for C. albicans polyamine transporters Dur3, Dur31, Dur33, Dur34, and were tested for Hst 5 sensitivity and uptake of spermidine. We found spermidine uptake and Hst 5 mediated killing were decreased significantly in Δdur3, Δdur31, and Δdur3/Δdur31 strains; whereas a DUR3 overexpression strain increased Hst 5 sensitivity and higher spermidine uptake. Treatment of cells with a spermidine synthase inhibitor increased spermidine uptake and Hst 5 killing, whereas protonophores and cold treatment reduced spermidine uptake. Inhibition assays showed that Hst 5 is a competitive analog of spermidine for uptake into C. albicans cells, and that Hst 5 Ki values were increased by 80-fold in Δdur3/Δdur31 cells. Thus, Dur3p and Dur31p are preferential spermidine transporters used by Hst 5 for its entry into candidal cells. Understanding of polyamine transporter-mediated internalization of Hst 5 provides new insights into the uptake mechanism for C. albicans toxicity, and further suggests design for targeted fungal therapeutic agents.
Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214.
Rohitashw
R
Kumar
Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214; Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Sonia
S
Chadha
Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214.
Darpan
D
Saraswat
Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214.
Jashanjot Singh
JS
Bajwa
Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214.
Rui A
RA
Li
Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214.
Heather R
HR
Conti
Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214. Electronic address: edgerto@buffalo.edu.
Mira
M
Edgerton
D000890:Anti-Infective Agents / Q000494:pharmacology; D001667:Binding, Competitive; D001896:Boron Compounds / Q000737:chemistry; D002176:Candida albicans / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D054808:Histatins / Q000378:metabolism*; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D018613:Microscopy, Confocal / Q000379:methods; D010802:Phylogeny; D010957:Plasmids / Q000378:metabolism; D011073:Polyamines / Q000737:chemistry*; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D013095:Spermidine / Q000737:chemistry; D013997:Time Factors
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D000890:Anti-Infective Agents; D001896:Boron Compounds; D027682:Cation Transport Proteins; C515373:DUR3 protein, S cerevisiae; C068075:HTN3 protein, human; D054808:Histatins; D026901:Membrane Transport Proteins; D011073:Polyamines; D029701:Saccharomyces cerevisiae Proteins; D013095:Spermidine