Identification and organization of chloroplastic and cytosolic l-myo-inositol 1-phosphate synthase coding gene(s) in Oryza sativa: comparison with the wild halophytic rice, Porteresia coarctata

Abstract

The gene coding for rice chloroplastic L-myo-inositol-1-phosphate synthase (MIPS; EC 5.5.1.4) has been identified by matrix-assisted laser desorption time-of-flight mass spectrometry analysis of the purified and immunologically cross-reactive approximately 60 kDa chloroplastic protein following two-dimensional polyacrylamide gel electrophoresis, which exhibited sequence identity with the cytosolic MIPS coded by OsINO1-1 gene. A possible chloroplastic transit peptide sequence was identified upstream of the OsINO1-1 gene upon analysis of rice genome. RT-PCR and confocal microscope studies confirmed transcription, effective translation and its functioning as a chloroplast transit peptide. Bioinformatic analysis mapped the chloroplastic MIPS (OsINO1-1) gene on chromosome 3, and a second MIPS gene (OsINO1-2) on chromosome 10 which lacks conventional chloroplast transit peptide sequence as in OsINO1-1. Two new PcINO1 genes, with characteristic promoter activity and upstream cis-elements were identified and cloned, but whether these proteins can be translocated to the chloroplast or not is yet to be ascertained. Electrophoretic mobility shift assay carried out with nuclear extract of Porteresia coarctata leaves grown under both control and stressed condition shows binding of nuclear proteins with the upstream elements. Nucleotide divergence among the different Oryza and Porteresia INO1 genes were calculated and compared.

Hydrogen peroxide and nitric oxide mediated cold‐ and dehydration‐induced myo‐inositol phosphate synthase that confers multiple resistances to abiotic stresses

“…2008), including wild halophytic rice P. coarctata (Majee et al . 2004), P. edulis (Abreu & Aragão 2007) and Oryza sativa (Ray et al . 2010).…”

“…2010), although there are reports that a chloroplastic isozyme of MIPS is found in rice, and PvMIPS can be expressed in membrane‐bound cellular compartments (Lackey et al . 2003; Ray et al . 2010).…”

“…MfMIPS1 was cloned from M. falcata in this study, with no signal, chloroplast transit or mitochondrial targeting peptide being predicted in MfMIPS1, suggesting that it might locate in the cytosol. MIPS has only been isolated in its soluble form (Lackey, Pope & Johnson 2003), or demonstrated to locate in cytosol (Donahue et al 2010), although there are reports that a chloroplastic isozyme of MIPS is found in rice, and PvMIPS can be expressed in membrane-bound cellular compartments (Lackey et al 2003;Ray et al 2010). Multiple myo-Inositol phosphate synthase and abiotic stress 295 alignments of amino acid sequence showed that MIPS is evolutionarily highly conserved.…”

MIPS sequences: a promising molecular consideration in angiosperm phylogeny and systematics

“…Although the MIPS gene was found in various plants with an almost similar sequence composition, their activity level has not been conserved (Khurana et al, 2012;Ray et al, 2010). These differences might also be attributed to the transcriptional and/or translational regulation or changes in the sequences.…”

L- Myo-Inositol 1-Phosphate Synthase (MIPS) in Chickpea: Gene Duplication and Functional Divergence

“…However, the biochemical and enzymatic properties of these two forms do not differ significantly between each other. Recent studies suggest that rice chloroplastic MIPS is coded by OsINO1-1 gene located on chromosome 3 (RayChaudhuri et al1997;Ray et al, 2010). The structural gene coding (INO1) for this ancient enzyme was first identified and cloned in Saccharomyces cerevisiae (Donahue & Henry,1981).…”