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| Title: Characterization of a rice chlorophyll-deficient mutant using the T-DNA gene-trap system .
| | Author: Jung KH Hur J Ryu CH Choi Y Chung YY Miyao A Hirochika H An G | | Journal: Plant Cell Physiol .
Year: 2003 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub12773632 Accession (PMID): 12773632 | | Abstract: We have previously generated a large pool of T-DNA insertional lines in rice .
In this study , we screened those T-DNA pools for rice mutants that had defective chlorophylls .
Among the 1 , 995 lines examined in the T2 generation , 189 showed a chlorophyll-deficient phenotype that segregated as a single recessive locus .
Among the mutants , 10 lines were beta-glucuronidase ( GUS ) -positive in the leaves .
Line 9-07117 has a T-DNA insertion into the gene that is highly homologous to XANTHA-F in barley and CHLH in ARABIDOPSIS : This OsCHLH gene encodes the largest subunit of the rice Mg-chelatase , a key enzyme in the chlorophyll branch of the tetrapyrrole biosynthetic pathway .
In the T2 and T3 generations , the chlorina mutant phenotypes are co-segregated with the T-DNA .
We have identified two additional chlorina mutants that have a Tos17 insertion in the OsCHLH gene .
Those phenotypes were co-segregated with Tos17 in the progeny .
GUS assays and RNA blot analysis showed that expression of the OsCHLH gene is light inducible , while TEM analysis revealed that the thylakoid membrane of the mutant chloroplasts is underdeveloped .
The chlorophyll content was very low in the OschlH mutants .
This is the first report that T-DNA insertional mutagenesis can be used for functional analysis of rice genes . | Matching Sentences:
[ Sen. 5, subscore: 1.00 ]: Line 9-07117 has a T-DNA insertion into the gene that is highly homologous to XANTHA-F in barley and CHLH in ARABIDOPSIS : This OsCHLH gene encodes the largest subunit of the rice Mg-chelatase , a key enzyme in the chlorophyll branch of the tetrapyrrole biosynthetic pathway .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
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| Title: Rice Chlorina-1 and Chlorina-9 encode ChlD and ChlI subunits of Mg-chelatase , a key enzyme for chlorophyll synthesis and chloroplast development .
| | Author: Zhang H Li J Yoo JH Yoo SC Cho SH Koh HJ Seo HS Paek NC .
| | Journal: Plant Mol . Biol . Year: 2006 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub16915519 Accession (PMID): 16915519 | | Abstract: Photosynthetic organisms exhibit a green color due to the accumulation of chlorophyll pigments in chloroplasts .
Mg-protoporphyrin IX chelatase ( Mg-chelatase ) comprises three subunits ( ChlH , ChlD and ChlI ) and catalyzes the insertion of Mg ( 2+ ) into protoporphyrin IX , the last common intermediate precursor in both chlorophyll and heme biosyntheses , to produce Mg-protoporphyrin IX ( MgProto ) .
Chlorophyll deficiency in higher plants results in chlorina ( yellowish-green ) phenotype .
To date , 10 chlorina ( chl ) mutants have been isolated in rice , but the corresponding genes have not yet been identified .
Rice Chl1 and Chl9 genes were mapped to chromosome 3 and isolated by map-based cloning .
A missense mutation occurred in a highly conserved amino acid of ChlD in the chl1 mutant and ChlI in the chl9 mutant .
Ultrastructural analyses have revealed that the grana are poorly stacked , resulting in the underdevelopment of chloroplasts .
In the seedlings fed with aminolevulinate-dipyridyl in darkness , MgProto levels in the chl1 and chl9 mutants decreased up to 25% and 31% of that in wild-type , respectively , indicating that the Mg-chelatase activity is significantly reduced , causing the eventual decrease in chlorophyll synthesis .
Furthermore , Northern blot analysis indicated that the nuclear genes encoding the three subunits of Mg-chelatase and LhcpII in chl1 mutant are expressed about 2-fold higher than those in WT , but are not altered in the chl9 mutant .
This result indicates that the ChlD subunit participates in negative feedback regulation of plastid-to-nucleus in the expression of nuclear genes encoding chloroplast proteins , but not the ChlI subunit . | Matching Sentences:
[ Sen. 2, subscore: 1.00 ]: Mg-protoporphyrin IX chelatase ( Mg-chelatase ) comprises three subunits ( ChlH , ChlD and ChlI ) and catalyzes the insertion of Mg ( 2+ ) into protoporphyrin IX , the last common intermediate precursor in both chlorophyll and heme biosyntheses , to produce Mg-protoporphyrin IX ( MgProto ) .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
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| Title: C-terminal residues of oryza sativa GUN4 are required for the activation of the ChlH subunit of magnesium chelatase in chlorophyll synthesis .
| | Author: Zhou S Sawicki A Willows RD Luo M | | Journal: FEBS Lett Year: 2012 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub22226678 Accession (PMID): 22226678 | | Abstract: Oryza sativa GUN4 together with the magnesium chelatase subunits ChlI , ChlD , and ChlH have been heterologously expressed and purified to reconstitute magnesium chelatase activity in vitro .
Maximum magnesium chelatase activity requires pre-activation of OsChlH with OsGUN4 , Mg ( 2+ ) and protoporphyrin-IX .
OsGUN4 and OsChlH preincubated without protoporphyrin-IX yields magnesium chelatase activity similar to assays without OsGUN4 , suggesting formation of a dead-end complex Either 9 or 10 C-terminal amino acids of OsGUN4 are slowly hydrolyzed to yield a truncated OsGUN4 .
These truncated OsGUN4 still bind protoporphyrin-IX and Mg-protoporphyrin-IX but are unable to activate OsChlH .
This suggests the mechanism of GUN4 activation of magnesium chelatase is different in eukaryotes compared to cyanobacteria as the orthologous cyanobacterial GUN4 proteins lack this C-terminal extension .
| Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: Oryza sativa GUN4 together with the magnesium chelatase subunits ChlI , ChlD , and ChlH have been heterologously expressed and purified to reconstitute magnesium chelatase activity in vitro .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
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| Title: C-terminal residues of oryza sativa GUN4 are required for the activation of the ChlH subunit of magnesium chelatase in chlorophyll synthesis .
| | Author: Zhou S Sawicki A Willows RD Luo M | | Journal: FEBS Lett Year: 2012 Type: MEDLINE | | Literature: oryza Field: title Doc ID: pub22226678 Accession (PMID): 22226678 | | Abstract: Oryza sativa GUN4 together with the magnesium chelatase subunits ChlI , ChlD , and ChlH have been heterologously expressed and purified to reconstitute magnesium chelatase activity in vitro .
Maximum magnesium chelatase activity requires pre-activation of OsChlH with OsGUN4 , Mg ( 2+ ) and protoporphyrin-IX .
OsGUN4 and OsChlH preincubated without protoporphyrin-IX yields magnesium chelatase activity similar to assays without OsGUN4 , suggesting formation of a dead-end complex Either 9 or 10 C-terminal amino acids of OsGUN4 are slowly hydrolyzed to yield a truncated OsGUN4 .
These truncated OsGUN4 still bind protoporphyrin-IX and Mg-protoporphyrin-IX but are unable to activate OsChlH .
This suggests the mechanism of GUN4 activation of magnesium chelatase is different in eukaryotes compared to cyanobacteria as the orthologous cyanobacterial GUN4 proteins lack this C-terminal extension .
| Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: C-terminal residues of oryza sativa GUN4 are required for the activation of the ChlH subunit of magnesium chelatase in chlorophyll synthesis .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
