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Open Access Research article

Cysteine peptidases and their inhibitors in Tetranychus urticae: a comparative genomic approach

María Estrella Santamaría1, Pedro Hernández-Crespo2, Félix Ortego2, Vojislava Grbic1, Miodrag Grbic1, Isabel Diaz3 and Manuel Martinez3*

Author Affiliations

1 Department of Biology WSC 339/341, The University of Western Ontario, 1151 Richmond St, London, ON N6A 5B7, Canada

2 Laboratorio de Interacción Planta-Insecto, Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040, Madrid, Spain

3 Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus Montegancedo, 28223-Pozuelo de Alarcón, Madrid, Spain

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BMC Genomics 2012, 13:307  doi:10.1186/1471-2164-13-307

Published: 11 July 2012

Abstract

Background

Cysteine peptidases in the two-spotted spider mite Tetranychus urticae are involved in essential physiological processes, including proteolytic digestion. Cystatins and thyropins are inhibitors of cysteine peptidases that modulate their activity, although their function in this species has yet to be investigated. Comparative genomic analyses are powerful tools to obtain advanced knowledge into the presence and evolution of both, peptidases and their inhibitors, and could aid to elucidate issues concerning the function of these proteins.

Results

We have performed a genomic comparative analysis of cysteine peptidases and their inhibitors in T. urticae and representative species of different arthropod taxonomic groups. The results indicate: i) clade-specific proliferations are common to C1A papain-like peptidases and for the I25B cystatin family of inhibitors, whereas the C1A inhibitors thyropins are evolutionarily more conserved among arthropod clades; ii) an unprecedented extensive expansion for C13 legumain-like peptidases is found in T. urticae; iii) a sequence-structure analysis of the spider mite cystatins suggests that diversification may be related to an expansion of their inhibitory range; and iv) an in silico transcriptomic analysis shows that most cathepsin B and L cysteine peptidases, legumains and several members of the cystatin family are expressed at a higher rate in T. urticae feeding stages than in embryos.

Conclusion

Comparative genomics has provided valuable insights on the spider mite cysteine peptidases and their inhibitors. Mite-specific proliferations of C1A and C13 peptidase and I25 cystatin families and their over-expression in feeding stages of mites fit with a putative role in mite’s feeding and could have a key role in its broad host feeding range.

Keywords:
Comparative genomics; Cystatins; Cysteine peptidases; Feeding; Tetranychus urticae; Thyropins