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BioMed Research International
Volume 2015 (2015), Article ID 286972, 8 pages
http://dx.doi.org/10.1155/2015/286972
Research Article

Analysis of the Isomerase and Chaperone-Like Activities of an Amebic PDI (EhPDI)

Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Calzada Universidad 14418, Parque Industrial Internacional, 22390 Tijuana, BCN, Mexico

Received 10 August 2014; Revised 20 November 2014; Accepted 24 November 2014

Academic Editor: Yun-Peng Chao

Copyright © 2015 Rosa E. Mares et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Protein disulfide isomerases (PDI) are eukaryotic oxidoreductases that catalyze the formation and rearrangement of disulfide bonds during folding of substrate proteins. Structurally, PDI enzymes share as a common feature the presence of at least one active thioredoxin-like domain. PDI enzymes are also involved in holding, refolding, and degradation of unfolded or misfolded proteins during stressful conditions. The EhPDI enzyme (a 38 kDa polypeptide with two active thioredoxin-like domains) has been used as a model to gain insights into protein folding and disulfide bond formation in E. histolytica. Here, we performed a functional complementation assay, using a ΔdsbC mutant of E. coli, to test whether EhPDI exhibits isomerase activity in vivo. Our preliminary results showed that EhPDI exhibits isomerase activity; however, further mutagenic analysis revealed significant differences in the functional role of each thioredoxin-like domain. Additional studies confirmed that EhPDI protects heat-labile enzymes against thermal inactivation, extending our knowledge about its chaperone-like activity. The characterization of EhPDI, as an oxidative folding catalyst with chaperone-like function, represents the initial step to dissect the molecular mechanisms involved in protein folding in E. histolytica.