Heparin Modulates the Endopeptidase Activity of Leishmania mexicana Cysteine Protease Cathepsin L-Like rCPB2.8: e80153

• Published in: PloS one 2013-11, Vol.8 (11)
• Main Authors: Judice, Wagner AS, Manfredi, Marcella A, Souza, Gerson P, Sansevero, Thiago M, Almeida, Paulo C, Shida, Claudio S, Gesteira, Tarsis F, Juliano, Luiz, Westrop, Gareth D, Sanderson, Sanya J
• Format: Article
• Language: English
• Subjects: Leishmania mexicana
• ISSN: 1932-6203
• DOI: 10.1371/journal.pone.0080153

Background Cysteine protease B is considered crucial for the survival and infectivity of the Leishmania in its human host. Several microorganism pathogens bind to the heparin-like glycosaminoglycans chains of proteoglycans at host-cell surface to promote their attachment and internalization. Here, we have investigated the influence of heparin upon Leishmania mexicana cysteine protease rCPB2.8 activity. Methodology/Principal Findings The data analysis revealed that the presence of heparin affects all steps of the enzyme reaction: (i) it decreases 3.5-fold the k1 and 4.0-fold the k-1, (ii) it affects the acyl-enzyme accumulation with pronounced decrease in k2 (2.7-fold), and also decrease in k3 (3.5-fold). The large values of Delta G = 12 kJ/mol for the association and dissociation steps indicate substantial structural strains linked to the formation/dissociation of the ES complex in the presence of heparin, which underscore a conformational change that prevents the diffusion of substrate in the rCPB2.8 active site. Binding to heparin also significantly decreases the alpha -helix content of the rCPB2.8 and perturbs the intrinsic fluorescence emission of the enzyme. The data strongly suggest that heparin is altering the ionization of catalytic (Cys25)-S-/(His163)-Im+ H ion pair of the rCPB2.8. Moreover, the interaction of heparin with the N-terminal pro-region of rCPB2.8 significantly decreased its inhibitory activity against the mature enzyme. Conclusions/Significance Taken together, depending on their concentration, heparin-like glycosaminoglycans can either stimulate or antagonize the activity of cysteine protease B enzymes during parasite infection, suggesting that this glycoconjugate can anchor parasite cysteine protease at host cell surface.