Title

Predictive inference on cytoplasmic and mitochondrial thioredoxin peroxidases in the highly radioresistant Lepidopteran insect Spodoptera frugiperda

Authors

Shashank Hambarde¹, Ragothaman M. Yennamalli^{2, 3}, Naidu Subbarao², Sudhir Chandna^*1

Affiliation

¹Natural Radiation Response Mechanisms Group, Division of Radiation Biosciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S.K. Mazumdar Road, Delhi -110054, India; ²Centre for Computational Biology and Bioinformatics, School of Information Technology, Jawaharlal Nehru University, New Mehrauli Road, New Delhi 110067 India; ³Present address: 1032 Crop Genome Informatics Laboratory, Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011-3260 USA

Email

sudhirchandna@yahoo.com

Article Type

Hypothesis

Date

Received December 09, 2009; revised December 28, 2009; accepted February 08, 2010; published March 31, 2010

Abstract

Lepidopteran insects show remarkable resistance to radiation and chemical stress than insects of other orders. Despite this, the antioxidant machinery of insects of this order is poorly understood. Recently we demonstrated the significance of cytoplasmic NOS and a stronger mitochondrial antioxidant enzyme system in the stress-resistance of Lepidopteran insects. In the present study, we hypothesize two thioredoxin peroxidase orthologues (Sf-TPx1 and Sf-TPx2) in Lepidopteran insect Spodoptera frugiperda and demonstrate their structural/functional features important for cellular antioxidant activity and stress resistance. Results show a higher mitochondrial localization score (WoLFPSORT) of Sf-TPx2 (mitochondria-18.0, cytoplasm-7.0, nucleus-4.0) than its Drosophila orthologue Jafrac2 (secretory-30.0; mitochondria/nucleus/cytoplasm-no signal), which is important for antioxidant activity, and a higher cytoplasmic localization score of Sf-TPx1 (mitochondria-no signal; cytoplasm-22.0; nucleus-3.5) than the Drosophila Jafrac1 (mitochondria-17; nucleus- 11; cytoplasm-no signal). Structural modeling data show certain motifs present in Jafrac1 and Jafrac2 that affect active site conformation and separate cysteine residues at distances not suitable for disulphide bridge formation (5.21Å; 5.73Å). These motifs are absent in Sf-TPx1 and Sf-TPx2, yielding shorter distance (2.01Å; 2.05Å) between the cysteine residues suitable for disulphide bridge formation. Taken together, the disulphide bridge as well as mitochondrial and cytoplasmic localization are crucial for peroxidatic activity of TPx’s. Therefore, we hypothesize that the Spodoptera TPx’s offer potentially stronger anti-oxidant activity than that of Drosophila orthologues, and may contribute in the high radioresistance of Lepidopteran insects.

Keywords

lepidopteran insects; cytoplasm; radiation; peroxidases

Citation

Hambarde et al., Bioinformation 4(9): 399-404 (2010)

Edited by

P. Kangueane

ISSN

0973-2063

Publisher

Biomedical Informatics

License

This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. This is distributed under the terms of the Creative Commons Attribution License.