Internalisation and degradation of histatin 5 by Candida albicans.
Histatins, salivary antimicrobial peptides, are susceptible to proteolytic degradation, often ascribed to host proteinases. In this study, we addressed the question whether proteolytic activity from microbial sources can contribute to this degradation. Candida albicans, an opportunistic yeast that is susceptible to the histatins, was used as target organism. The most potent histatin (histatin 5: sequence: DSHAKRHHGYKRKFHEKHHSHRGY), two histatin 5 fragments (dh-5: sequence: KRKFHEKHHSHRGY; P-113: sequence: AKRHHGYKRKFH) and an all-D isomer of the latter (P-113D) were used as model peptides. All L-peptides were susceptible to degradation by C. albicans. Cleavage was established at Lys5 and His19 of histatin 5, Lys11, Arg12, Phe14, Glu16, Lys17, His18 and Ser20 of dh-5 and Ala4 and Lys11 of P-113. In addition, it was found that secreted C. albicans enzymes are not involved in the degradation process and that blocking cell entry of the peptides greatly impedes degradation. Moreover, P-113D, which is biologically as active as P-113, was hardly susceptible to proteolysis. These data imply that proteolysis occurs mainly intracellularly and is not used as a protective mechanism against histatin activity. Together, our results suggest that, besides host proteinases, microbial enzymes play an important role in histatin degradation.
Ruissen
Anita L A
AL
Department of Dental Basic Sciences, Section of Oral Biochemistry, Academic Centre for Dentistry Amsterdam (ACTA), Vrije Universiteit, Van der Boechorststraat 7, NL-1081 BT Amsterdam, The Netherlands.
Groenink
Jasper
J
Krijtenberg
Patricia
P
Walgreen-Weterings
Els
E
van 't Hof
Wim
W
Veerman
Enno C I
EC
Nieuw Amerongen
Arie V
AV
D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000378:metabolism* / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism; D054808:Histatins; D008826:Microbial Sensitivity Tests; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification; D011480:Protease Inhibitors / Q000494:pharmacology; D012471:Salivary Proteins and Peptides / Q000378:metabolism* / Q000494:pharmacology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013237:Stereoisomerism
D000935:Antifungal Agents; C068075:HTN3 protein, human; D054808:Histatins; D010455:Peptides; D011480:Protease Inhibitors; D012471:Salivary Proteins and Peptides; D010450:Endopeptidases