title: Purification, refolding and autoactivation of the recombinant cysteine proteinase EhCP112 from Entamoeba histolytica.
abstract: The cysteine proteinase EhCP112 and the adhesin EhADH112 assemble to form the EhCPADH complex involved in Entamoeba histolytica virulence. To further characterize this cysteine proteinase, the recombinant full-length EhCP112 enzyme was expressed and purified under denaturing conditions. After a refolding step under reductive conditions, the inactive precursor (ppEhCP112) was processed to a 35.5 kDa mature and active enzyme (EhCP112). The thiol specific inhibitor E-64, but not serine or aspartic proteinase inhibitors arrested this activation process. The activation step of the proenzyme followed by the mature enzyme suggests an autocatalytic process during EhCP112 maturation. The experimentally determined processing sites observed during EhCP112 activation lie close to processing sites of other cysteine proteinases from parasites. The kinetic parameters of the mature EhCP112 were determined using hemoglobin and azocasein as substrates. The proteinase activity of EhCP112 was completely inhibited by thiol inhibitors, E-64, TLCK, and chymostatin, but not by general proteinase inhibitors. Since EhCP112 is a proteinase involved in the virulence of E. histolytica, a reliable source of active EhCP112 is a key step for its biochemical characterization and to carry out future protein structure-function studies.
authors.affiliation: Department of Biotechnology and Bioengineering, Centro de Investigación y Estudios Avanzados del IPN (CINVESTAV-IPN), Av. IPN # 2508, Col. San Pedro Zacatenco, CP 07360 Mexico City, Mexico.
authors.forename: Laura I
authors.initials: LI
authors.lastname: Quintas-Granados
authors.forename: Esther
authors.initials: E
authors.lastname: Orozco
authors.forename: Luis G
authors.initials: LG
authors.lastname: Brieba
authors.forename: Rossana
authors.initials: R
authors.lastname: Arroyo
authors.forename: Jaime
authors.initials: J
authors.lastname: Ortega-López
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D002364:Caseins / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004748:Entamoeba histolytica / Q000201:enzymology*; D004792:Enzyme Precursors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017510:Protein Folding; D020673:Protein Renaturation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013053:Spectrophotometry
chemical_list: D001426:Bacterial Proteins; D002364:Caseins; D004792:Enzyme Precursors; D011994:Recombinant Proteins; C026018:azocasein; D003546:Cysteine Endopeptidases; C122004:EhCP112 protein, Entamoeba histolytica