L-myo-lnositol 1-Phosphate Synthase from Plant Sources (Characteristics of the Chloroplastic and Cytosolic Enzymes)

Raychaudhuri, Aniruddha; Hait, Nitai C.; Dasgupta, Saumya; Bhaduri, Tirtha Jyoti; Deb, Rajib; Majumder, Arun Lahiri

doi:10.1104/pp.115.2.727

Cited by 50 publications

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References 46 publications

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“…Purification of Cytosolic MIPS from Oryza and Porteresia LeavesCytosolic MIPS from leaves of O. sativa and P. coarctata were isolated following the procedure developed in this laboratory (20). Low speed supernatant from the leaf homogenate was subjected to 40 -70% (NH 4 ) 2 SO 4 precipitation.…”

Section: Methodsmentioning

confidence: 99%

“…The supernatant was dialyzed serially (step dialysis with 8, 7, 6, 5, 4, 3, and 2 M urea and finally with urea-free buffer) to remove urea. Dialyzed expressed protein sample was purified by DEAE-Sephacel and Bio-Gel A0.5 as for the native enzyme described earlier (20).…”

Section: Methodsmentioning

confidence: 99%

“…(18 -22). The chloroplastic form of the enzyme has been found to be similar to the cytosolic enzyme, with respect to biochemical and immunological properties (20), and was demonstrated to be regulated by light and salt (21). At least two molecular forms of the enzyme having ϳ80-and ϳ60-kDa subunits have been identified in rice chloroplasts.…”

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A Novel Salt-tolerant l-myo-Inositol-1-phosphate Synthase from Porteresia coarctata (Roxb.) Tateoka, a Halophytic Wild Rice

Majee

Maitra

Dastidar

et al. 2004

Journal of Biological Chemistry

172

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L-myo-Inositol-1-phosphate synthase (EC 5.5.1.4, MIPS), an evolutionarily conserved enzyme protein, catalyzes the synthesis of inositol, which is implicated in a number of metabolic reactions in the biological kingdom. Here we report on the isolation of the gene (PINO1) for a novel salt-tolerant MIPS from the wild halophytic rice, Porteresia coarctata (Roxb.) Tateoka. Identity of the PINO1 gene was confirmed by functional complementation in a yeast inositol auxotrophic strain. Comparison of the nucleotide and deduced amino acid sequences of PINO1 with that of the homologous gene from Oryza sativa L. (RINO1) revealed distinct differences in a stretch of 37 amino acids, between amino acids 174 and 210. Purified bacterially expressed PINO1 protein demonstrated a salt-tolerant character in vitro compared with the salt-sensitive RINO1 protein as with those purified from the native source or an expressed salt-sensitive mutant PINO1 protein wherein amino acids 174 -210 have been deleted. Analysis of the salt effect on oligomerization and tryptophan fluorescence of the RINO1 and PINO1 proteins revealed that the structure of PINO1 protein is stable toward salt environment. Furthermore, introgression of PINO1 rendered transgenic tobacco plants capable of growth in 200 -300 mM NaCl with retention of ϳ40 -80% of the photosynthetic competence with concomitant increased inositol production compared with unstressed control. MIPS protein isolated from PINO1 transgenics showed salt-tolerant property in vitro confirming functional expression in planta of the PINO1 gene. To our knowledge, this is the first report of a salt-tolerant MIPS from any source.Inositols are six-carbon cyclohexane hexitols found ubiquitously in the biological kingdom, and its metabolism plays a vital role in growth regulation, membrane biogenesis, osmotolerance, and in many other processes. As phosphorylated derivatives, its role as a phosphorus store and as a "second messenger" in signal transduction pathways has long been recognized. myo-Inositol, physiologically the most favored stereoisomer among the eight possible geometric isomers of inositol, also enters into an array of biochemical reactions having diverse functions in cellular metabolism both as free and conjugated and phosphorylated or methylated forms (1-3).The primary enzyme for the synthesis of L-myo-inositol 1-phosphate from glucose 6-phosphate is L-myo-inositol-1-phosphate synthase (EC 5.5.1.4; referred to as MIPS), 1 which synthesizes L-myo-inositol 1-phosphate through an internal oxidoreduction reaction involving NAD ϩ . Free inositol is generated by dephosphorylation of the MIPS product by a specific Mg 2ϩ -dependent inositol-1-phosphate phosphatase (EC 3.1.3.25). This mechanism is followed by all myo-inositolproducing organisms throughout the phylogenetic lines, and MIPS has been identified as an evolutionarily conserved protein (4). The structural gene coding for cytosolic MIPS, termed INO1, was first identified in yeast, Saccharomyces cerevisiae (5, 6) and cloned by Klig and Henry (7)....

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 96%

mentioning

confidence: 99%

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A Novel Salt-tolerant l-myo-Inositol-1-phosphate Synthase from Porteresia coarctata (Roxb.) Tateoka, a Halophytic Wild Rice

Majee

Maitra

Dastidar

et al. 2004

Journal of Biological Chemistry

172

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“…The deduced cDNA sequences of IMT and INPS included N-terminal sequences without any recognizable homology to chloroplast transit peptides, but the localization of INPS activity in chloroplasts has been reported from higher plants (RayChaudhuri et al, 1997). To study whether the two proteins might be located in the cytosol or in chloroplasts, extracts of total cell protein of NaCl-treated plants were compared with protein extracts from chloroplasts ( Figure 3).…”

Section: Imt and Inps Protein Analysismentioning

confidence: 99%

Regulation of Cell-Specific Inositol Metabolism and Transport in Plant Salinity Tolerance

1998

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myo-Inositol and its derivatives are commonly studied with respect to cell signaling and membrane biogenesis, but they also participate in responses to salinity in animals and plants. In this study, we focused on L -myo -inositol 1-phosphate synthase (INPS), which commits carbon to de novo synthesis, and myo -inositol O -methyltransferase (IMT), which uses myo -inositol for stress-induced accumulation of a methylinositol, D -ononitol. The Imt and Inps promoters are transcriptionally controlled. We determined that the transcription rates, transcript levels, and protein abundance are correlated. During normal growth, INPS is present in all cells, but IMT is repressed. After salinity stress, the amount of INPS was enhanced in leaves but repressed in roots. IMT was induced in all cell types. The absence of myo -inositol synthesis in roots is compensated by inositol/ononitol transport in the phloem. The mobilization of photosynthate through myo -inositol translocation links root metabolism to photosynthesis. Our model integrates the transcriptional control of a specialized metabolic pathway with physiological reactions in different tissues. The tissue-specific differential regulation of INPS, which leads to a gradient of myo -inositol synthesis, supports root growth and sodium uptake. By inducing expression of IMT and increasing myo -inositol synthesis, metabolic end products accumulate, facilitating sodium sequestration and protecting photosynthesis. INTRODUCTIONA central focus of our work is to determine genes that underlie mechanisms providing salinity tolerance in higher plants. In addition, we hope to learn how whole plants adapt metabolically. Many researchers have studied tolerance mechanisms in plants. Their findings show the importance of metabolite accumulation, which generally is attributed to osmotic adjustment leading to water retention and/or protection of biochemical pathways. When single enzymes were tested in transgenic plants, the accumulation of mannitol, proline, fructans, trehalose, glycine betaine, or ononitol (Tarczynski et al., 1993;Kavi Kishor et al., 1995;Pilon-Smits et al., 1995;Holmström et al., 1996;Hayashi et al., 1997;Sheveleva et al., 1997) provided marginally higher salinity and cold or drought tolerance. The manipulation of biochemical pathways by the transfer of multiple genes will be an even more appropriate strategy that is expected to provide broader tolerance because salinity tolerance is a multigenic trait Warne et al., 1995;Bohnert and Jensen, 1996). Salinity tolerance is also a multicellular trait, and the remodeling of complex pathways in transgenic plants will require knowledge of the distribution of such pathways throughout the plant. We have analyzed the myo -inositol biosynthetic pathway-leading to methylated inositols-that feeds into a pathway specific to salinity tolerance in a halophyte, the common ice plant ( Mesembryanthemum crystallinum ) (Loewus and Dickinson, 1982;Vernon and Bohnert, 1992).myo -Inositol is a central component of several biochemical pathways. It i...

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Evolutionary Divergence of L-myo-Inositol 1-Phosphate Synthase: Significance of a “Core Catalytic Structure”

Dastidar

Chatterjee

et al.

Subcellular Biochemistry

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L-myo-lnositol 1-Phosphate Synthase from Plant Sources (Characteristics of the Chloroplastic and Cytosolic Enzymes)

Cited by 50 publications

References 46 publications

A Novel Salt-tolerant l-myo-Inositol-1-phosphate Synthase from Porteresia coarctata (Roxb.) Tateoka, a Halophytic Wild Rice

A Novel Salt-tolerant l-myo-Inositol-1-phosphate Synthase from Porteresia coarctata (Roxb.) Tateoka, a Halophytic Wild Rice

Regulation of Cell-Specific Inositol Metabolism and Transport in Plant Salinity Tolerance

Evolutionary Divergence of L-myo-Inositol 1-Phosphate Synthase: Significance of a “Core Catalytic Structure”

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