| 7 matches found in 4 documents. Search time: 0.344 seconds. |
|---|
|
Score: 4.00 |
|---|
| Title: Activation of the indole-3-acetic acid-amido synthetase GH3-8 suppresses expansin expression and promotes salicylate and jasmonate-independent basal immunity in rice .
| | Author: Ding X Cao Y Huang L Zhao J Xu C Li X Wang S | | Journal: Plant Cell Citation: V : 20 P : 228-40 Year: 2008 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub18192436 Accession (PMID): 18192436 | | Abstract: New evidence suggests a role for the plant growth hormone auxin in pathogenesis and disease resistance .
Bacterial infection induces the accumulation of indole-3-acetic acid ( IAA ) , the major type of auxin , in rice ( Oryza sativa ) .
IAA induces the expression of expansins , proteins that loosen the cell wall .
Loosening the cell wall is key for plant growth but may also make the plant vulnerable to biotic intruders .
Here , we report that rice GH3-8 , an auxin-responsive gene functioning in auxin-dependent development , activates disease resistance in a salicylic acid signaling and jasmonic acid signaling-independent pathway .
GH3-8 encodes an IAA-amino synthetase that prevents free IAA accumulation .
Overexpression of GH3-8 results in enhanced disease resistance to the rice pathogen Xanthomonas oryzae pv oryzae .
This resistance is independent of jasmonic acid and salicylic acid signaling .
Overexpression of GH3-8 also causes abnormal plant morphology and retarded growth and development .
Both enhanced resistance and abnormal development may be caused by inhibition of the expression of expansins via suppressed auxin signaling .
| Matching Sentences:
[ Sen. 5, subscore: 1.00 ]: Here , we report that rice GH3-8 , an auxin-responsive gene functioning in auxin-dependent development , activates disease resistance in a salicylic acid signaling and jasmonic acid signaling-independent pathway .
[ Sen. 6, subscore: 1.00 ]: GH3-8 encodes an IAA-amino synthetase that prevents free IAA accumulation .
[ Sen. 7, subscore: 1.00 ]: Overexpression of GH3-8 results in enhanced disease resistance to the rice pathogen Xanthomonas oryzae pv oryzae .
[ Sen. 9, subscore: 1.00 ]: Overexpression of GH3-8 also causes abnormal plant morphology and retarded growth and development .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: A liquid chromatography-tandem mass spectrometry-based assay for indole-3-acetic acid-amido synthetase .
| | Author: Chen Q Zhang B Hicks LM Wang S Jez JM | | Journal: Anal Biochem Citation: V : 390 P : 149-54 Year: 2009 Type: In-Process | | Literature: oryza Field: abstract Doc ID: pub19393612 Accession (PMID): 19393612 | | Abstract: Indole-3-acetic acid ( IAA ) amide conjugates play an important role in balancing levels of free IAA in plant cells .
The GH3 family of proteins conjugates free IAA with various amino acids .
For example , auxin levels modulate expression of the Oryza sativa ( rice ) GH3-8 protein , which acts to prevent IAA accumulation by coupling the hormone to aspartate .
To examine the kinetic properties of the enzyme , we developed a liquid chromatography-tandem mass spectrometry ( LC-MS/MS ) assay system .
Bacterially expressed OsGH3-8 was purified to homogeneity and used to establish the assay system .
Monitoring of the reaction confirms the reaction product as IAA-Asp and demonstrates that production of the conjugate increases proportionally with both time and enzyme amount .
Steady-state kinetic analysis using the LC-MS/MS-based assay yields the following parameters : V/E ( t ) ( IAA ) =20 . 3 min ( -1 ) , K ( m ) ( IAA ) =123 microM , V/E ( t ) ( ATP ) =14 . 1 min ( -1 ) , K ( m ) ( ATP ) =50 microM , V/E ( t ) ( Asp ) =28 . 8 min ( -1 ) , K ( m ) ( Asp ) =1580 microM .
This is the first assignment of kinetic values for any IAA-amido synthetase from plants .
Compared with previously described LC and thin-layer chromatography ( TLC ) -based assays , this LC-MS/MS method provides a robust and sensitive means for performing direct kinetic studies on a range of IAA-conjugating enzymes .
| Matching Sentences:
[ Sen. 3, subscore: 1.00 ]: For example , auxin levels modulate expression of the Oryza sativa ( rice ) GH3-8 protein , which acts to prevent IAA accumulation by coupling the hormone to aspartate .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: Kinetic basis for the conjugation of auxin by a GH3 family indole-acetic acid-amido synthetase .
| | Author: Chen Q Westfall CS Hicks LM Wang S Jez JM | | Journal: J Biol Chem Citation: V : 285 P : 29780-6 Year: 2010 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub20639576 Accession (PMID): 20639576 | | Abstract: The GH3 family of acyl-acid-amido synthetases catalyze the ATP-dependent formation of amino acid conjugates to modulate levels of active plant hormones , including auxins and jasmonates .
Initial biochemical studies of various GH3s show that these enzymes group into three families based on sequence relationships and acyl-acid substrate preference ( I , jasmonate-conjugating ; II , auxin and salicylic acid-conjugating ; III , benzoate-conjugating ) ; however , little is known about the kinetic and chemical mechanisms of these enzymes .
Here we use GH3-8 from Oryza sativa ( rice ; OsGH3-8 ) , which functions as an indole-acetic acid ( IAA ) -amido synthetase , for detailed mechanistic studies .
Steady-state kinetic analysis shows that the OsGH3-8 requires either Mg ( 2+ ) or Mn ( 2+ ) for maximal activity and is specific for aspartate but accepts asparagine as a substrate with a 45-fold decrease in catalytic efficiency and accepts other auxin analogs , including phenyl-acetic acid , indole butyric acid , and naphthalene-acetic acid , as acyl-acid substrates with 1 . 4-9-fold reductions in k ( cat ) /K ( m ) relative to IAA .
Initial velocity and product inhibition studies indicate that the enzyme uses a Bi Uni Uni Bi Ping Pong reaction sequence .
In the first half-reaction , ATP binds first followed by IAA .
Next , formation of an adenylated IAA intermediate results in release of pyrophosphate .
The second half-reaction begins with binding of aspartate , which reacts with the adenylated intermediate to release IAA-Asp and AMP .
Formation of a catalytically competent adenylated-IAA reaction intermediate was confirmed by mass spectrometry .
These mechanistic studies provide insight on the reaction catalyzed by the GH3 family of enzymes to modulate plant hormone action .
| Matching Sentences:
[ Sen. 3, subscore: 1.00 ]: Here we use GH3-8 from Oryza sativa ( rice ; OsGH3-8 ) , which functions as an indole-acetic acid ( IAA ) -amido synthetase , for detailed mechanistic studies .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: Activation of the indole-3-acetic acid-amido synthetase GH3-8 suppresses expansin expression and promotes salicylate and jasmonate-independent basal immunity in rice .
| | Author: Ding X Cao Y Huang L Zhao J Xu C Li X Wang S | | Journal: Plant Cell Citation: V : 20 P : 228-40 Year: 2008 Type: MEDLINE | | Literature: oryza Field: title Doc ID: pub18192436 Accession (PMID): 18192436 | | Abstract: New evidence suggests a role for the plant growth hormone auxin in pathogenesis and disease resistance .
Bacterial infection induces the accumulation of indole-3-acetic acid ( IAA ) , the major type of auxin , in rice ( Oryza sativa ) .
IAA induces the expression of expansins , proteins that loosen the cell wall .
Loosening the cell wall is key for plant growth but may also make the plant vulnerable to biotic intruders .
Here , we report that rice GH3-8 , an auxin-responsive gene functioning in auxin-dependent development , activates disease resistance in a salicylic acid signaling and jasmonic acid signaling-independent pathway .
GH3-8 encodes an IAA-amino synthetase that prevents free IAA accumulation .
Overexpression of GH3-8 results in enhanced disease resistance to the rice pathogen Xanthomonas oryzae pv oryzae .
This resistance is independent of jasmonic acid and salicylic acid signaling .
Overexpression of GH3-8 also causes abnormal plant morphology and retarded growth and development .
Both enhanced resistance and abnormal development may be caused by inhibition of the expression of expansins via suppressed auxin signaling .
| Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: Activation of the indole-3-acetic acid-amido synthetase GH3-8 suppresses expansin expression and promotes salicylate and jasmonate-independent basal immunity in rice .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
