Comparative in silico Analysis of Phosphoglycerate Kinase (PGK) Genes in Selected Plants

Phosphoglycerate kinase (PGK; EC 2.7.2.3) is a major phosphoryl group transfer enzyme which catalyzes the formation of ATP to ADP in glycolysis, the generation of ATP in fermentation and carbon fixation. The enzyme is found in all living organisms, particularly in plants with two main cytosolic and chloroplastic isoforms. In this study, PGK gene and protein sequences from six selected plants were identified. Nucleotide level analysis showed higher sequence variation in lower plants compared to higher plants. PGK expression profiles in Arabidopsis found to be correlated with the energy demand of cells based on their anatomical parts and developmental stages. Protein sequence lengths were in 398-597 range, mainly resulting from N-terminal “transit peptide” residues in chloroplastic isoforms. PGK proteins were 28.39-63.73 kDa in molecular weight with 5.47-8.92 pI value. Phylogenetically, chloroplastic and cytosolic PGKs of higher and lower plants belonged to different branches with a distinct separation. In spite of the well-conserved topological structure found in modelled proteins, and similar biochemical activities of cytosolic and chloroplastic PGK forms, different binding residues were predicted to involve in catalysis of biochemical reactions in glycolysis/gluconeogenesis (cytosolic form) and Calvin cycle (chloroplastic form). These divergences in PGKs either do not change the protein structure, stability and function or they bare new functional roles at species-dependent way.