Molecular and structural analysis of C 4-specific PEPC isoform from Pennisetum glaucum plays a role in stress adaptation

Jitender Singh, Guda Maheedhara Reddy, Aakrati Agarwal, Kottakota Chandrasekhar, S. K. Sopory, M. K. Reddy, Tanushri Kaul

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Phosphoenolpyruvate carboxylase is an ubiquitous cytosolic enzyme that catalyzes the ß-carboxylation of phosphoenolpyruvate (PEP) and is encoded by multigene family in plants. It plays an important role in carbon economy of plants by assimilating CO 2 into organic acids for subsequent C 4 or CAM photosynthesis or to perform several anaplerotic roles in non-photosynthetic tissues. In this study, a cDNA clone encoding for PEPC polypeptide possessing signature motifs characteristic to ZmC 4PEPC was isolated from Pennisetum glaucum (PgPEPC). Deduced amino acid sequence revealed its predicted secondary structure consisting of forty alpha helices and eight beta strands is well conserved among other PEPC homologs irrespective of variation in their primary amino acid sequences. Predicted PgPEPC quartenary structure is a tetramer consisting of a dimer of dimers, which is globally akin to maize PEPC crystal structure with respect to major chain folding wherein catalytically important amino acid residues of active site geometry are conserved. Recombinant PgPEPC protein expressed in E. coli and purified to homogeneity, possessed in vitro ß-carboxylation activity that is determined using a coupled reaction converting PEP into malate. Tetramer is the most active form, however, it exists in various oligomeric forms depending upon the protein concentration, pH, ionic strength of the media and presence of its substrate or effecters. Recombinant PgPEPC protein confers enhanced growth advantage to E. coli under harsh growth conditions in comparison to their respective controls; suggesting that PgPEPC plays a significant role in stress adaptation.

Original languageEnglish
Pages (from-to)224-231
Number of pages8
JournalGene
Volume500
Issue number2
DOIs
StatePublished - 1 Jun 2012
Externally publishedYes

Keywords

  • Abiotic stress
  • Carboxylation activity
  • Dynamic light scattering spectroscopy
  • Escherichia coli
  • Gel-permeation chromatography
  • Tetramer

ASJC Scopus subject areas

  • Genetics

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