title: Identification and characterization of CaApe2--a neutral arginine/alanine/leucine-specific metallo-aminopeptidase from Candida albicans.
abstract: The proteolytic potential of the pathogenic fungus Candida albicans was evaluated by the identification and functional characterization of a peptidolytic enzyme isolated from the cell wall of the microorganism. Determination of basic structural and kinetic data identified a neutral arginine/alanine/leucine-specific metallo-aminopeptidase of unknown function termed CaApe2, which is encoded by ORF CaO19.5197 (GenBank RefSeq XM_705313). Mass spectrometric tryptic peptide analysis and N-terminal protein sequencing revealed serine-88 to represent the N-terminus of CaApe2. Taking into account the results of DNA and protein sequence analysis including inspection of the genomic region upstream of ORF CaO19.5197, the gene CaAPE2 is likely to consist of two exons linked by a phase-2 intron with exons 1 and 2 encoding a signal peptide and the amino acids 88-954 of ORF CaO19.5197, respectively. The isolated CaApe2 protein shares an equally high similarity with the gene products ScAap1 and ScApe2, suggesting duplication of a phylogenetically ancient precursor gene in Saccharomyces cerevisiae. The observed failure to cleave human type-I and type-IV collagen in vitro challenges a direct role that secreted CaApe2 might play in the degradation of extracellular matrix components during host colonization, but does not exclude per se a contribution of the aminopeptidase to the pathogenicity of C. albicans.
authors.affiliation: Poliklinik für Zahnerhaltung, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Klinke
authors.forename: Andreas
authors.initials: A
authors.lastname: Rump
authors.forename: Roman
authors.initials: R
authors.lastname: Pönisch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schellenberger
authors.forename: Eva-Christina
authors.initials: EC
authors.lastname: Müller
authors.forename: Albrecht
authors.initials: A
authors.lastname: Otto
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Klimm
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Kriegel
mesh_terms: D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001120:Arginine / Q000737:chemistry; D001483:Base Sequence; D002176:Candida albicans / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D002473:Cell Wall / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D005656:Fungal Proteins; D001120:Arginine; D000626:Aminopeptidases; D007931:Leucyl Aminopeptidase; D000409:Alanine