title: Functional characterization of a putative aquaporin from Encephalitozoon cuniculi, a microsporidia pathogenic to humans.
abstract: The microsporidia are a group of obligate intracellular parasitic protists that have been implicated as both human and veterinary pathogens. The infectious process of these organisms is believed to be dependent upon the rapid influx of water into spores, presumably via aquaporins (AQPs), transmembrane channels that facilitate osmosis. An AQP-like sequence of the microsporidium Encephalitozoon cuniculi (EcAQP), when cloned and expressed in oocytes of Xenopus laevis, rendered these oocytes highly permeable to water. No permeability to the solutes glycerol or urea was observed. Pre-treatment of EcAQP-expressing oocytes with HgCl(2) failed to inhibit their osmotic permeability, as predicted from EcAQP's lack of mercury-sensitive cysteine residues near the NPA motifs which line the AQP aqueous pore. EcAQP exhibits sequence identity to AQP A of Dictyostelium discoideum (26%) and human AQP 2 (24%). Further study of AQPs in microsporidia and their potential inhibitors may yield novel therapeutic agents for microsporidian infections.
authors.affiliation: Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Kaya
authors.initials: K
authors.lastname: Ghosh
authors.forename: Clint D
authors.initials: CD
authors.lastname: Cappiello
authors.forename: Sean M
authors.initials: SM
authors.lastname: McBride
authors.forename: James L
authors.initials: JL
authors.lastname: Occi
authors.forename: Ann
authors.initials: A
authors.lastname: Cali
authors.forename: Peter M
authors.initials: PM
authors.lastname: Takvorian
authors.forename: Thomas V
authors.initials: TV
authors.lastname: McDonald
authors.forename: Louis M
authors.initials: LM
authors.lastname: Weiss
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020346:Aquaporins / Q000032:analysis* / Q000378:metabolism; D002478:Cells, Cultured; D004023:Dictyostelium; D009670:Encephalitozoon cuniculi / Q000737:chemistry*; D016890:Encephalitozoonosis / Q000378:metabolism; D005656:Fungal Proteins / Q000032:analysis* / Q000378:metabolism; D005990:Glycerol / Q000494:pharmacology; D006801:Humans; D008627:Mercuric Chloride / Q000494:pharmacology; D009865:Oocytes / Q000502:physiology; D009995:Osmosis / Q000187:drug effects; D010802:Phylogeny; D011817:Rabbits; D016415:Sequence Alignment / Q000379:methods; D020539:Sequence Analysis, Protein / Q000379:methods; D012997:Solvents / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology; D014982:Xenopus laevis / Q000502:physiology
chemical_list: D020346:Aquaporins; D005656:Fungal Proteins; D012997:Solvents; D008627:Mercuric Chloride; D014508:Urea; D005990:Glycerol