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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/26948
Title: X-ray crystallographic structural characteristics of Arabidopsis hemoglobin I and their functional implications
Authors: Mukhi N.
Dhindwal S.
Uppal S.
Kumar, Pravindra R.Manish
Kaur J.
Kundu S.
Published in: Biochimica et Biophysica Acta - Proteins and Proteomics
Abstract: Genome of the model dicot flowering plant, Arabidopsis thaliana, a popular tool for understanding molecular biology of plant physiology, encodes all three classes of plant hemoglobins that differ in their sequence, ligand binding and spectral properties. As such these globins are of considerable attention. Crystal structures of few members of plant class I nonsymbiotic hemoglobin have been described earlier. Here we report the crystal structure of Arabidopsis class I hemoglobin (AHb1) to 2.2 Å and compare its key features with the structures of similar nonsymbiotic hemoglobin from other species. Crystal structure of AHb1 is homologous to the related members with similar globin fold and heme pocket architecture. The structure is homodimeric in the asymmetric unit with both distal and proximal histidines coordinating to the heme iron atom. Residues lining the dimeric interface are also conserved in AHb1 with the exception of additional electrostatic interaction between H112 and E113 of each subunit and that involving Y119 through two water molecules. In addition, differences in heme pocket non-covalent interactions, a novel Ser residue at F7 position, Xe binding site variability, internal cavity topology differences, CD loop conformation and stability and other such properties might explain kinetic variability in AHb1. Detailed cavity analysis of AHb1 showed the presence of a novel long tunnel connecting the distal pockets of both the monomers. Presence of such tunnel, along with confor-mational heterogeneity observed in the two chains, might suggest cooperative ligand binding and support its role in NO scavenging. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins. © 2013 Elsevier B.V. All rights reserved.
Citation: Biochimica et Biophysica Acta - Proteins and Proteomics, 1834(9): 1944-1956
URI: https://doi.org/10.1016/j.bbapap.2013.02.024
http://repository.iitr.ac.in/handle/123456789/26948
Issue Date: 2013
Publisher: Elsevier B.V.
Keywords: AHb1
Arabidopsis hemoglobin 1
Crystal structure
Nonsymbiotic plant hemoglobin
Tunnel between heme groups
ISSN: 15709639
Author Scopus IDs: 55630780900
36082537700
35082765800
55064809000
13610600400
7201407194
Author Affiliations: Mukhi, N., Department of Genetics, University of Delhi, South Campus, New Delhi 110021, India
Dhindwal, S., Department of Biotechnology, Indian Institute of Technology, Roorkee, Uttarakhand 247667, India
Uppal, S., Department of Biochemistry, University of Delhi, South Campus, New Delhi 110021, India
Kumar, P., Department of Biotechnology, Indian Institute of Technology, Roorkee, Uttarakhand 247667, India
Kaur, J., Department of Genetics, University of Delhi, South Campus, New Delhi 110021, India
Kundu, S., Department of Biochemistry, University of Delhi, South Campus, New Delhi 110021, India
Funding Details: We acknowledge Macromolecular Crystallography Unit (MCU), Institute Instrumentation Centre, IIT Roorkee (PK) for X-ray diffraction experiments. Help with HPLC experiments by Richa Arya and Dr. Monica Sundd, National Institute of Immunology, New Delhi, is acknowledged. Sanjay Kumar Dey is acknowledged for helping with tunnel calculations by varying isocontour values. We also appreciate financial assistance from the Delhi University (DU) and the Department of Science and Technology (DST), Government of India under the PURSE program (JK, SK). Research fellowships from UGC, Government of India to NM and CSIR, Government of India to SU are also acknowledged. Department of Science and Technology, Ministry of Science and Technology, India, डीएसटी; Council of Scientific and Industrial Research, India, CSIR; University Grants Committee, UGC; University of Delhi, DU
Corresponding Author: Kaur, J.; Department of Genetics, South Campus, New Delhi 110021, India; email: jagreet@south.du.ac.in
Appears in Collections:Journal Publications [BT]

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