|
|
| Line 1: |
Line 1: |
| − | As a member of '''TPS/TPP gene family''', '''''OsTPP2(Oryza sativa Trehalose-6-phosphate phosphatase2)''''' confers '''stress tolerance''' in rice<ref name="ref1"/><ref name="ref2"/>.
| |
| − |
| |
| − | ==Annotated Information==
| |
| − | ===Function===
| |
| − | *''OsTPP2'' encodes a functional trehalose-6-phosphate phosphatase enzyme. A full-length OsTPP2 cDNA was then isolated from root tissue by RT-PCR. The OsTPP2 gene contained an ORF encoding a 42.6 kDa protein with 382 amino acid residues<ref name="ref1"/>.
| |
| − |
| |
| − | *Expression of ''OsTPP2'' was regulated by '''multiple stress factors''', such as '''chilling''', '''drought''', and '''salt''' stresses, as well as '''ABA''' treatment. Enzymatic characterization of recombinant ''OsTPP1'' and ''OsTPP2'' revealed stringent substrate specificity for trehalose 6-phosphate and about 10 times lower Km values for trehalose 6-phosphate as compared with trehalose-6-phosphate phosphatase enzymes from microorganisms<ref name="ref1"/>.
| |
| − |
| |
| − | '''GO assignment(s):''' [http://amigo.geneontology.org/amigo/term/GO:0003824 GO:0003824], [http://amigo.geneontology.org/amigo/term/GO:0005992 GO:0005992], [http://amigo.geneontology.org/amigo/term/GO:0008152 GO:0008152]
| |
| − |
| |
| − | ===[[Os02g0661100|'''''OsTPP1''''']] and OsTPP2'''''===
| |
| − | *'''Enzymatic characterization''' of recombinant ''OsTPP1'' and ''OsTPP2'' revealed '''stringent substrate specificity''' for trehalose 6-phosphate and about 10 times '''lower Km values''' for trehalose 6-phosphate as compared with trehalose-6-phosphate phosphatase enzymes from microorganisms<ref name="ref1"/>.
| |
| − | *''OsTPP1'' and ''OsTPP2'' also clearly contrasted with microbial enzymes, in that they are generally unstable, almost completely losing activity when subjected to heat treatment at 50°C for 4 min. These characteristics of rice trehalose-6-phosphate phosphatase enzymes are '''consistent with very low cellular substrate concentration''' and '''tightly regulated gene expression'''<ref name="ref1"/>.
| |
| − | *''OsTPP1'' and ''OsTPP2'' were the major TPP genes expressed in rice '''seedlings'''<ref name="ref1"/>.
| |
| − | *Both ''OsTPP1'' and ''OsTPP2'' '''exhibited strong phosphatase activity upon Tre6P''', but almost no activity (less than 1% relative to Tre6P) was detected with any of the other sugar phosphates tested (data not shown).
| |
| − | *'''The pH optima''' of OsTPP1 and OsTPP2 were approximately 7.0 and 6.5, respectively, whereas the enzymes had almost no activity at pH 5.5 or 9<ref name="ref1"/>.
| |
| − | *Heat treatment at 50°C or higher for 4 min nearly eliminated both OsTPP1 and OsTPP2 activity, indicating that both enzymes are heat-labile<ref name="ref1"/>.
| |
| − |
| |
| − | ===Mutation===
| |
| − | *yeast ''△tps2'' mutant<ref name="ref1"/>:
| |
| − | Whereas wild-type cells grow at both 30°C and 36°C, growth of the ''△tps2'' mutant at 36°C was inhibited because of its inability
| |
| − | to synthesize trehalose. The same mutant yeast strain transformed with ''OsTPP2'' recovered wild-type levels of growth at 36°C, suggesting that ''OsTPP2'' is a '''functional TPP enzyme''' in yeast cells.
| |
| − |
| |
| − | ===Expression===
| |
| − | *''OsTPP2'' mRNA levels were detectable prior to stress treatments, and transiently increased in response to '''low temperature''', peaking at 10 h after the initiation of treatment in both '''shoot and root tissues'''. This expression pattern contrasted with the observed rapid induction of [[Os02g0661100|''OsTPP1'']] and gradual induction of ''OsMEK1''<ref name="ref3"/> in response to low temperature treatment<ref name="ref2"/><ref name="ref3"/>.
| |
| − | *''Drought stress'' transiently induced ''OsTPP2'' expression, which peaked at 6 h in shoots and 2 h in roots. The induction of ''OsTPP2'' expression occurs earlier during stress treatment compared with expression of another drought-induced gene (''salT'') [25]. Treatment with 150 mm '''NaCl''' also induced OsTPP2 expression in roots, suggesting that stresses associated with water deficit similarly affect expression of this gene<ref name="ref1"/>.
| |
| − | *However, in contrast to '''chilling and drought stress''' treatments, clear induction of ''OsTPP2'' was not observed in shoots, whereas the salt treatment effectively induced salT in both roots and shoots. Slight and transient induction of OsTPP2 was observed in roots and shoots in response to exogenous '''ABA'''. Together, these expression analyses indicated involvement of ''OsTPP2'' in '''multiple stress responses'''<ref name="ref3"/>.
| |
| − |
| |
| − | ===Evolution===
| |
| − | [[File: TPP Phylogenetic1.jpg|right|thumb|300px|'''Figure 1.''' ''Phylogenetic analysis of TPP domains.(from reference <ref name="ref4"/>).'']]
| |
| − | *Phylogenetic analysis of the TPP domains demonstrated that the '''whole TPS/TPP gene family''' in rice was grouped into '''three''' classes (Class I/II/III)(Fig. 1). '''Class I''' consisted of '''''OsTPS1''''' which displayed high identity to '''''AtTPS1'''''<ref name="ref5"/> and '''''SlTPS1'''''<ref name="ref6"/>; '''Class II''' consisted of all the '''remaining OsTPSs'''; and '''Class III''' consisted of '''all independent TPP genes'''. The phylogenetic tree displayed a similar structure to that in ''Arabidopsis''<ref name="ref7"/>, suggesting the gene family was '''highly conserved''' and formed before the divergence of dicotyledonous and monocotyledonous angiosperms<ref name="ref1"/><ref name="ref4"/>.
| |
| − |
| |
| − | *''OsTPP2'' belongs to '''Class III'''<ref name="ref4"/>.
| |
| − |
| |
| − | *'''Amino acid sequence homology''' between '''''OsTPP2''''' and '''''OsTPP1''''' was '''53%'''. Greater '''similarity''' was observed between OsTPP2 and ''Arabidopsis'' '''AtTPPA''' ('''57%'''). OsTPP2 contains '''two motifs''' shared by all TPP enzymes, known as phosphatase boxes<ref name="ref4"/>.
| |
| − |
| |
| − | ===Knowledge Extension===
| |
| − | [[File: trehalose metabolic pathways1.jpg|left|thumb|300px|'''Figure 2.''' ''Identified trehalose metabolic pathways.(from reference <ref name="ref8"/>).'']]
| |
| − |
| |
| − | *Although five different trehalose synthesis pathways exist in bacteria, fungi, yeast and algae, trehalose biosynthesis in higher plants only occurs in the trehalose phosphate synthase (TPS)–trehalose phosphate phosphatase(TPP) pathway (also known as OtsA–OtsB pathway)(Figure 2). The first step, catalyzed by TPS, involves the binding of a glucose-6-P to a UDP-glucose to produce T6P, which is cleaved into trehalose by TPP<ref name="ref9"/>. Trehalase breaks down trehalose to form two glucose residues. This process has been found in all organisms that synthesize trehalose<ref name="ref9"/>, even when distinct forms of trehalase coexist<ref name="ref10"/>.
| |
| − |
| |
| − | *Trehalose is a disaccharide sugar '''widely distributed''' in bacteria, fungi, insects, plants and invertebrate animals. In microbes and yeast, trehalose is produced from glucose by trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP), and serves as a sugar storage, metabolic regulator and protects against abiotic stress<ref name="ref10"/><ref name="ref11"/>. However, its role in plants is not yet fully elucidated<ref name="ref4"/><ref name="ref10"/><ref name="ref11"/>.
| |
| − |
| |
| − |
| |
| − | ==Labs working on this gene==
| |
| − | *Crop Cold Tolerance Research Team, National Agricultural Research Center for Hokkaido Region, National Agriculture and Food Research Organization, Hitsujigaoka 1, Toyohira-ku, Sapporo 0628555, Japan
| |
| − | *Department of Crop Botany, Bangladesh Agricultural University, Mymensing, Bangladesh
| |
| − |
| |
| − |
| |
| − | ==References==
| |
| − | <references>
| |
| − | * <ref name="ref1">
| |
| − | Shima S, Matsui H, Tahara S, et al. Biochemical characterization of rice trehalose‐6‐phosphate phosphatases supports distinctive functions of these plant enzymes[J]. FEBS Journal, 2007, 274(5): 1192-1201.
| |
| − | </ref>
| |
| − | * <ref name="ref2">
| |
| − | Pramanik M H R, Imai R. Functional identification of a trehalose 6-phosphate phosphatase gene that is involved in transient induction of trehalose biosynthesis during chilling stress in rice[J]. Plant molecular biology, 2005, 58(6): 751-762.
| |
| − | </ref>
| |
| − | * <ref name="ref3">
| |
| − | Wen J Q, Oono K, Imai R. Two novel mitogen-activated protein signaling components, OsMEK1 and OsMAP1, are involved in a moderate low-temperature signaling pathway in rice[J]. Plant physiology, 2002, 129(4): 1880-1891.
| |
| − | </ref>
| |
| − | * <ref name="ref4">
| |
| − | Ge L F, Chao D Y, Shi M, et al. Overexpression of the trehalose-6-phosphate phosphatase gene OsTPP1 confers stress tolerance in rice and results in the activation of stress responsive genes[J]. Planta, 2008, 228(1): 191-201.
| |
| − | </ref>
| |
| − | * <ref name="ref5">
| |
| − | Blazquez M A, Santos E, Flores C, et al. Isolation and molecular characterization of the Arabidopsis TPS1 gene, encoding trehalose‐6‐phosphate synthase[J]. The Plant Journal, 1998, 13(5): 685-689.
| |
| − | </ref>
| |
| − | * <ref name="ref6">
| |
| − | Zentella R, Mascorro-Gallardo J O, Van Dijck P, et al. A Selaginella lepidophylla Trehalose-6-Phosphate Synthase Complements Growth and Stress-Tolerance Defects in a Yeasttps1 Mutant[J]. Plant Physiology, 1999, 119(4): 1473-1482.
| |
| − | </ref>
| |
| − | * <ref name="ref7">
| |
| − | Leyman B, Van Dijck P, Thevelein J M. An unexpected plethora of trehalose biosynthesis genes in< i> Arabidopsis thaliana</i>[J]. Trends in plant science, 2001, 6(11): 510-513.
| |
| − | </ref>
| |
| − | * <ref name="ref8">
| |
| − | Fernandez O, Béthencourt L, Quero A, et al. Trehalose and plant stress responses: friend or foe?[J]. Trends in plant science, 2010, 15(7): 409-417.
| |
| − | </ref>
| |
| − | * <ref name="ref9">
| |
| − | Paul M J, Primavesi L F, Jhurreea D, et al. Trehalose metabolism and signaling[J]. Annu. Rev. Plant Biol., 2008, 59: 417-441.
| |
| − | </ref>
| |
| − | * <ref name="ref10">
| |
| − | Wiemken A. Trehalose in yeast, stress protectant rather than reserve carbohydrate[J]. Antonie van Leeuwenhoek, 1990, 58(3): 209-217.
| |
| − | </ref>
| |
| − | * <ref name="ref11">
| |
| − | Strom A R, Kaasen I. Trehalose metabolism in Escherichia coli: stress protection and stress regulation of gene expression[J]. Molecular microbiology, 1993, 8(2): 205-210.
| |
| − | </ref>
| |
| − | </references>
| |
| − |
| |
| | [[Category:Genes]] | | [[Category:Genes]] |
| | [[Category:Japonica mRNA]] | | [[Category:Japonica mRNA]] |
