Modulation of the exocellular serine-thiol proteinase activity of Paracoccidioides brasiliensis by neutral polysaccharides

Modulation of the exocellular serine-thiol proteinase activity of Paracoccidioides brasiliensis by neutral polysaccharides

Autor Matsuo, A. L. Google Scholar
Tersariol, IIL Google Scholar
Kobata, S. I. Google Scholar
Travassos, L. R. Google Scholar
Carmona, A. K. Google Scholar
Puccia, R. Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Univ Mogi Cruzes
Resumo Our group characterized an exocellular serine-thiol proteinase activity in the yeast phase of Paracoccidioides brasiliensis (PbST), a dimorphic human pathogen. the fungal proteinase is able to cleave in vitro, at pH 7.4, proteins associated with the basal membrane, such as human laminin and fibronectin, type IV collagen and proteoglycans. in the present study, we investigated the influence of glycosaminoglycans (GAGs) and neutral polysaccharides upon the serine-thiol proteinase activity by means of kinetic analysis monitored with fluorescence resonance energy transfer (FRET) peptides using the substrate Abz-MKALTLQ-EDDnp (Abz = ortho-aminobenzoic acid; EDDnp = ethylenedia-minedinitrophenyl). Only neutral polysaccharides exhibited patterns of interaction with the protemase, while sulfated GAGs had no effect. Incubation with neutral polysaccharides resulted in a powerful modulation of the enzyme activity, intensely changing the enzyme kinetic parameters of catalysis and affinity for the substrate. Commercial dextran at the highest concentration of 20 PM increased 6.8-fold the enzyme affinity for the substrate. in the presence of 8 mu M of purified baker's yeast mannan, the apparent K. of the enzyme increased about 5.5-fold, reflecting a significant inhibition in binding to the peptide substrate. When an exocellular galactomannan (GalMan) complex isolated from P brasiliensis was added to the reaction mixture at 400 nM, the apparent K-M and V-MAX decreased about threefold. Moreover, GalMan was able to protect the enzymatic activity at high temperatures, but it caused no effect on the optimum cleavage pH. Our results show a novel modulation mechanism in P. brasiliensis, where a fungal polysaccharide-rich component can stabilize a serine-thiol proteolytic activity, which is possibly involved in fungal dissemination. (c) 2005 Elsevier SAS. All rights reserved.
Assunto Paracoccidioides brasiliensis
serine-thiol activity
neutral polysaccharides
Idioma Inglês
Data 2006-01-01
Publicado em Microbes and Infection. Amsterdam: Elsevier B.V., v. 8, n. 1, p. 84-91, 2006.
ISSN 1286-4579 (Sherpa/Romeo, fator de impacto)
Editor Elsevier B.V.
Extensão 84-91
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000235441700010

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