2003 Fiscal Year Final Research Report Summary
Multiforn of γ-Glutamyltransfemse in Higher Plants and Cysteine Recycle
| Project/Area Number |
14560052
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Plant nutrition/Soil science
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
SEKIYA Jiro KYOTO UNIVERSITY, Graduate School of Agriculture, Professor, 農学研究科, 教授 (10035123)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KOIZUMI Yukio KYOTO UNIVERSITY, Graduate School of Agriculture, Instructor, 農学研究科, 助手 (40293914)
|
|---|
| Project Period (FY) |
2002 – 2003
|
| Keywords | γ-glutamyltransferase / mdish / bound γ-glutamyltransferase / soluble γ-glutamyltransferase / transgenic tobacco / multiform / glutathione catabolism |
|---|
| Research Abstract |
1 Occurrence of two forms of radish γ-glutamyltransferases (GGT; EC.2.3.2.2), soluble and cell wall bound ones, were demonstrated in many plants including radish (Raphanus sativus).
2 We cloned three cDNAs (rsggt1, AB098475; rsggt2, AB102676;rsggt3, unregistered) predicted to encode radish soluble GGTs, sequenced them and analyzed their properties. These cDNA seems to encode a heterodimeric type of GGTs homologous to mammalians GGTs.
3 These three genes were transcribed by organ and tissue specific manner: rsggt1 was expressed characteristically in immature seeds and cotyledons; rsggt2 in cotyledons, leaves and roots; and rsggt 3 in leaves, roots and immature seeds.
4 We transformed tobacco plants with rsggt1 and rsggt2. Transformed tobacco plants grew normally. They developed higher level of GGT activity, although wild type tobacco plants exhibited a very low GGT activity. Expressed GGT activity was found in the bound fraction, although cDNA used encoded soluble radish GGT. To understand this discrepancy remains to be solved in future.
5 We purified bound GGTs from radish cotyledons. The bound GGT was a monomeric enzyme unlike soluble GGTs. cDNA was presumed to be highly homologous to Arabidopsis cDNA (AK118068) encoding putative β-1,3-glucanase. Tobacco plants transformed with putative β-1,3-glucanase cDNA exhibited elevated level of GGT activity, but not β-1,3-glucanase.
6 We measured thiol compounds in apoplastic space of leaves of transgenic and wild type tobacco plants. Decreased level of glutathione (GSH) and elevated level of cysteinylglycine, a product of GGT reaction, were found in transgenic plants. These findings suggest that cell wall bound GGTs participate in GSH catabolism in apoplastic space.
|
