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Identification, characterisation and molecular modelling of two AP endonucleases from base excision repair pathway in sugarcane provide insights on the early evolution of green plants

Authors

  • N. Maira,

    1. Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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    • These authors contributed equally to this work.
  • T. M. Torres,

    1. Departamento de Bioquímica, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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    • These authors contributed equally to this work.
  • A. L. de Oliveira,

    1. Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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  • S. R. B. de Medeiros,

    1. Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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  • L. F. Agnez-Lima,

    1. Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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  • J. P. M. S. Lima,

    1. Departamento de Bioquímica, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
    2. Institute of Tropical Medicine of Rio Grande do Norte (IMT-RN), Universidade Federal do Rio Grande do Norte, Natal, Brazil
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  • K. C. Scortecci

    Corresponding author
    1. Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
    • Correspondence

      K. C. Scortecci, Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN 59072-970, Brazil.

      E-mail: kcscortecci@ufrnet.br

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Abstract

Unlike bacteria and mammals, plant DNA repair pathways are not well characterised, especially in monocots. The understanding of these processes in the plant cell is of major importance, since they may be directly involved in plant acclimation and adaptation to stressful environments. Hence, two sugarcane ESTs were identified as homologues of AP endonuclease from the base-excision repair pathway: ScARP1 and ScARP3. In order to understand their probable function and evolutionary origin, structural and phylogenetic studies were performed using bioinformatics approaches. The two predicted proteins present a considerable amino acid sequence similarity, and molecular modelling procedures indicate that both are functional, since the main structural motifs remain conserved. However, inspection of the sort signal regions on the full-length cDNAs indicated that these proteins have a distinct organelle target. Furthermore, variances in their promoter cis-element motifs were also found. Although the mRNA expression pattern was similar, there were significant differences in their expression levels. Taken together, these data raise the hypothesis that the ScARP is an example of a probable gene duplication event that occurred before monocotyledon/dicotyledon segregation, followed by a sub-functionalisation event in the Poaceae, leading to new intracellular targeting and different expression levels.

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