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Title: Structural Insight into DFMO Resistant Ornithine Decarboxylase from Entamoeba histolytica: An Inkling to Adaptive Evolution
Authors: Preeti
Tapas S.
Kumar, Pravindra R.Manish
Madhubala R.
Tomar, Shailly
Published in: PLoS ONE
Abstract: Background: Polyamine biosynthetic pathway is a validated therapeutic target for large number of infectious diseases including cancer, giardiasis and African sleeping sickness, etc. ?-Difluoromethylornithine (DFMO), a potent drug used for the treatment of African sleeping sickness is an irreversible inhibitor of ornithine decarboxylase (ODC), the first rate limiting enzyme of polyamine biosynthesis. The enzyme ODC of E. histolytica (EhODC) has been reported to exhibit resistance towards DFMO. Methodology/Principal Finding: The basis for insensitivity towards DFMO was investigated by structural analysis of EhODC and conformational modifications at the active site. Here, we report cloning, purification and crystal structure determination of C-terminal truncated Entamoeba histolytica ornithine decarboxylase (EhODC?15). Structure was determined by molecular replacement method and refined to 2.8 Å resolution. The orthorhombic crystal exhibits P212121 symmetry with unit cell parameters a = 76.66, b = 119.28, c = 179.28 Å. Functional as well as evolutionary relations of EhODC with other ODC homologs were predicted on the basis of sequence analysis, phylogeny and structure. Conclusions/Significance: We determined the tetrameric crystal structure of EhODC?15, which exists as a dimer in solution. Insensitivity towards DFMO is due to substitution of key substrate binding residues in active site pocket. Additionally, a few more substitutions similar to antizyme inhibitor (AZI), a non-functional homologue of ODCs, were identified in the active site. Here, we establish the fact that EhODC sequence has conserved PLP binding residues; in contrast few substrate binding residues are mutated similar to AZI. Further sequence analysis and structural studies revealed that EhODC may represent as an evolutionary bridge between active decarboxylase and inactive AZI. © 2013 Preeti et al.
Citation: PLoS ONE(2013), 8(1): -
Issue Date: 2013
ISSN: 19326203
Author Scopus IDs: 35103173800
Author Affiliations: Preeti, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
Tapas, S., Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
Kumar, P., Department of Biotechnology
Corresponding Author: Tomar, S.; Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India; email:
Appears in Collections:Journal Publications [BT]

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