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Biosynthesis and possible functions of inositol pyrophosphates in plants.

Williams SP, Gillaspy GE, Perera IY - Front Plant Sci (2015)

Bottom Line: Most eukaryotes synthesize the precursor molecule, myo-inositol (1,2,3,4,5,6)-hexakisphosphate (InsP6), which can serve as a signaling molecule or as storage compound of inositol, phosphorus, and minerals (referred to as phytic acid).Recent work has delineated that Arabidopsis has two genes capable of PP-InsP5 synthesis, and PPx-InsPs have been detected across the plant kingdom.This review will detail the known roles of PPx-InsPs in yeast and animal systems, and provide a description of recent data on the synthesis and accumulation of these novel molecules in plants, and potential roles in signaling.

View Article: PubMed Central - PubMed

Affiliation: Biochemistry, Virginia Polytechnic and State University Blacksburg, VA, USA.

ABSTRACT
Inositol phosphates (InsPs) are intricately tied to lipid signaling, as at least one portion of the inositol phosphate signaling pool is derived from hydrolysis of the lipid precursor, phosphatidyl inositol (4,5) bisphosphate. The focus of this review is on the inositol pyrophosphates, which are a novel group of InsP signaling molecules containing diphosphate or triphosphate chains (i.e., PPx) attached to the inositol ring. These PPx-InsPs are emerging as critical players in the integration of cellular metabolism and stress signaling in non-plant eukaryotes. Most eukaryotes synthesize the precursor molecule, myo-inositol (1,2,3,4,5,6)-hexakisphosphate (InsP6), which can serve as a signaling molecule or as storage compound of inositol, phosphorus, and minerals (referred to as phytic acid). Even though plants produce huge amounts of precursor InsP6 in seeds, almost no attention has been paid to whether PPx-InsPs exist in plants, and if so, what roles these molecules play. Recent work has delineated that Arabidopsis has two genes capable of PP-InsP5 synthesis, and PPx-InsPs have been detected across the plant kingdom. This review will detail the known roles of PPx-InsPs in yeast and animal systems, and provide a description of recent data on the synthesis and accumulation of these novel molecules in plants, and potential roles in signaling.

No MeSH data available.


Schematic alignment of the kinase and phosphatase domains of VIPs. The ATP grasp/RimK/ kinase (ATP-grasp) and the histidine acid Phosphatase (Phosphatase) domains within the VIP proteins from Homo sapiens (Hs, Genbank AAH57395), Saccharomyces cerevisiae (Sc, NP_013514) and Arabidopsis thaliana (AtVip1 Gene ID, 821297; AtVip2 Gene ID, 831359). The red asterisks denotes in both panels the conserved aspartic acid residue (D) required for kinase activity, and the black dot, the known phosphorylated serine residues within the Arabidopsis VIPs. The lower panel contains the amino acid alignment of the boundary region between the ATP-Grasp and Phosphatase domains. The beginning of the Histidine Acid phosphatase domain is boxed, followed by the PH domain and Arg417 is marked by the blue arrow.
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Figure 4: Schematic alignment of the kinase and phosphatase domains of VIPs. The ATP grasp/RimK/ kinase (ATP-grasp) and the histidine acid Phosphatase (Phosphatase) domains within the VIP proteins from Homo sapiens (Hs, Genbank AAH57395), Saccharomyces cerevisiae (Sc, NP_013514) and Arabidopsis thaliana (AtVip1 Gene ID, 821297; AtVip2 Gene ID, 831359). The red asterisks denotes in both panels the conserved aspartic acid residue (D) required for kinase activity, and the black dot, the known phosphorylated serine residues within the Arabidopsis VIPs. The lower panel contains the amino acid alignment of the boundary region between the ATP-Grasp and Phosphatase domains. The beginning of the Histidine Acid phosphatase domain is boxed, followed by the PH domain and Arg417 is marked by the blue arrow.

Mentions: The Vip genes are conserved across eukaryotes, including plants (Mulugu et al., 2007; Desai et al., 2014). They have a dual domain structure consisting of an N-terminal ATP grasp domain with kinase activity and a C-terminal histidine acid phosphatase domain or “phytase” domain (Mulugu et al., 2007) (see Figure 4). The human PPIP5K1 phosphatase domain is not active with InsP5, InsP6, PP-InsP4, or PP-InsP5 as the substrate or even p-nitrophenyl phosphate, a generic substrate for acid phosphatases (Gokhale et al., 2011). This is probably due to the fact that PPIP5Ks lack a conserved histidine essential for phosphatase activity. In addition, the phosphatase catalytic region is interrupted by a Pleckstrin Homology (PH) domain (Gokhale et al., 2011). The PH domain is found in signaling proteins and is responsible for binding phospholipids or molecules derived from their head group (Scheffzek and Welti, 2012). The hybrid PH domain in PPIP5K1 preferentially binds PtdIns(3,4,5)P3 and can also bind InsP6 allowing PPIP5K1 to translocate from the cytoplasm to the plasma membrane when the PtdIns(3,4,5)P3 signaling pathway is activated (Gokhale et al., 2011). Critical to ligand binding is arginine 417 in the PH domain of PPIP5K1 (Gokhale et al., 2011).


Biosynthesis and possible functions of inositol pyrophosphates in plants.

Williams SP, Gillaspy GE, Perera IY - Front Plant Sci (2015)

Schematic alignment of the kinase and phosphatase domains of VIPs. The ATP grasp/RimK/ kinase (ATP-grasp) and the histidine acid Phosphatase (Phosphatase) domains within the VIP proteins from Homo sapiens (Hs, Genbank AAH57395), Saccharomyces cerevisiae (Sc, NP_013514) and Arabidopsis thaliana (AtVip1 Gene ID, 821297; AtVip2 Gene ID, 831359). The red asterisks denotes in both panels the conserved aspartic acid residue (D) required for kinase activity, and the black dot, the known phosphorylated serine residues within the Arabidopsis VIPs. The lower panel contains the amino acid alignment of the boundary region between the ATP-Grasp and Phosphatase domains. The beginning of the Histidine Acid phosphatase domain is boxed, followed by the PH domain and Arg417 is marked by the blue arrow.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4325660&req=5

Figure 4: Schematic alignment of the kinase and phosphatase domains of VIPs. The ATP grasp/RimK/ kinase (ATP-grasp) and the histidine acid Phosphatase (Phosphatase) domains within the VIP proteins from Homo sapiens (Hs, Genbank AAH57395), Saccharomyces cerevisiae (Sc, NP_013514) and Arabidopsis thaliana (AtVip1 Gene ID, 821297; AtVip2 Gene ID, 831359). The red asterisks denotes in both panels the conserved aspartic acid residue (D) required for kinase activity, and the black dot, the known phosphorylated serine residues within the Arabidopsis VIPs. The lower panel contains the amino acid alignment of the boundary region between the ATP-Grasp and Phosphatase domains. The beginning of the Histidine Acid phosphatase domain is boxed, followed by the PH domain and Arg417 is marked by the blue arrow.
Mentions: The Vip genes are conserved across eukaryotes, including plants (Mulugu et al., 2007; Desai et al., 2014). They have a dual domain structure consisting of an N-terminal ATP grasp domain with kinase activity and a C-terminal histidine acid phosphatase domain or “phytase” domain (Mulugu et al., 2007) (see Figure 4). The human PPIP5K1 phosphatase domain is not active with InsP5, InsP6, PP-InsP4, or PP-InsP5 as the substrate or even p-nitrophenyl phosphate, a generic substrate for acid phosphatases (Gokhale et al., 2011). This is probably due to the fact that PPIP5Ks lack a conserved histidine essential for phosphatase activity. In addition, the phosphatase catalytic region is interrupted by a Pleckstrin Homology (PH) domain (Gokhale et al., 2011). The PH domain is found in signaling proteins and is responsible for binding phospholipids or molecules derived from their head group (Scheffzek and Welti, 2012). The hybrid PH domain in PPIP5K1 preferentially binds PtdIns(3,4,5)P3 and can also bind InsP6 allowing PPIP5K1 to translocate from the cytoplasm to the plasma membrane when the PtdIns(3,4,5)P3 signaling pathway is activated (Gokhale et al., 2011). Critical to ligand binding is arginine 417 in the PH domain of PPIP5K1 (Gokhale et al., 2011).

Bottom Line: Most eukaryotes synthesize the precursor molecule, myo-inositol (1,2,3,4,5,6)-hexakisphosphate (InsP6), which can serve as a signaling molecule or as storage compound of inositol, phosphorus, and minerals (referred to as phytic acid).Recent work has delineated that Arabidopsis has two genes capable of PP-InsP5 synthesis, and PPx-InsPs have been detected across the plant kingdom.This review will detail the known roles of PPx-InsPs in yeast and animal systems, and provide a description of recent data on the synthesis and accumulation of these novel molecules in plants, and potential roles in signaling.

View Article: PubMed Central - PubMed

Affiliation: Biochemistry, Virginia Polytechnic and State University Blacksburg, VA, USA.

ABSTRACT
Inositol phosphates (InsPs) are intricately tied to lipid signaling, as at least one portion of the inositol phosphate signaling pool is derived from hydrolysis of the lipid precursor, phosphatidyl inositol (4,5) bisphosphate. The focus of this review is on the inositol pyrophosphates, which are a novel group of InsP signaling molecules containing diphosphate or triphosphate chains (i.e., PPx) attached to the inositol ring. These PPx-InsPs are emerging as critical players in the integration of cellular metabolism and stress signaling in non-plant eukaryotes. Most eukaryotes synthesize the precursor molecule, myo-inositol (1,2,3,4,5,6)-hexakisphosphate (InsP6), which can serve as a signaling molecule or as storage compound of inositol, phosphorus, and minerals (referred to as phytic acid). Even though plants produce huge amounts of precursor InsP6 in seeds, almost no attention has been paid to whether PPx-InsPs exist in plants, and if so, what roles these molecules play. Recent work has delineated that Arabidopsis has two genes capable of PP-InsP5 synthesis, and PPx-InsPs have been detected across the plant kingdom. This review will detail the known roles of PPx-InsPs in yeast and animal systems, and provide a description of recent data on the synthesis and accumulation of these novel molecules in plants, and potential roles in signaling.

No MeSH data available.