Document Detail

Wild-type opaque2 and defective opaque2 polypeptides form complexes in maize endosperm cells and bind the opaque2-zein target site.
MedLine Citation:
PMID:  17827273     Owner:  NLM     Status:  MEDLINE    
The Opaque2 (O2) basic leucine (Leu)-zipper transcriptional activator controls the expression of several genes in maize (Zea mays). We investigated the phosphorylation extent of wild-type O2 and mutant-defective or mutant-truncated o2 polypeptides in endosperm cells, their subcellular localization, participation in complex formation, and involvement in functional activity. Besides wild type, four mutant alleles (o2T, o2-52, o2It, and o2-676) producing o2 polypeptides and a null transcript allele (o2R) were considered. Observing the effects of these mutations, multiphosphorylation events in O2 or o2 proteins were confirmed and further investigated, and the involvement of both the nuclear localization signal (NLS)-B and Leu-zipper domains in proper targeting to the nucleus was ascertained. The absence of these domains in the o2T and o2It-S mutant-truncated forms holds them within the cytoplasm, where they are partially phosphorylated, whereas the presence of NLS-B and a partial Leu-zipper domain in o2-52 distributes this mutant-truncated form in both cytoplasm and nucleus. Although mutated in the NLS-B domain, the o2It-L and o2-676 mutant-defective forms are, respectively, partially or completely distributed into the nucleus. Only wild-type O2 and mutant-defective o2 polypeptides bearing the Leu-zipper are able to form complexes whose components were proven to bind the O2-zein target site by in vitro analyses. The transcription of a subset of H-zein genes as well as H-zein polypeptide accumulation in several o2-mutant-defective genotypes indicate the in vivo involvement of o2-mutant-defective proteins in O2-zein target site recognition. The gathered information broadens our knowledge on O2 functional activity and our view on possible quality protein maize trait manipulation or plant transformation via the utilization of cisgenic elements.
Floriana Gavazzi; Barbara Lazzari; Pietro Ciceri; Elisabetta Gianazza; Angelo Viotti
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-09-07
Journal Detail:
Title:  Plant physiology     Volume:  145     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-11-06     Completed Date:  2008-01-14     Revised Date:  2010-09-15    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  933-45     Citation Subset:  IM    
Istituto Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, I-20133 Milan, Italy.
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MeSH Terms
DNA-Binding Proteins / genetics*,  metabolism*
Gene Expression Regulation, Plant
Plant Proteins / genetics*,  metabolism*
Protein Binding
Protein Isoforms
Protein Transport
Seeds / growth & development,  metabolism
Transcription Factors / genetics*,  metabolism*
Transcription, Genetic
Zea mays / cytology,  genetics*,  metabolism*
Zein / genetics,  metabolism
Reg. No./Substance:
0/DNA-Binding Proteins; 0/Plant Proteins; 0/Protein Isoforms; 0/Transcription Factors; 0/opaque-2 protein, Zea mays; 9010-66-6/Zein

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