DNase I and micrococcal nuclease analysis of the tomato proteinase inhibitor I gene in chromatin.
The chromatin structure of the wound-inducible proteinase inhibitor I gene was investigated in nuclei from leaves of wounded and unwounded tomato plants. DNase I digestion of intact nuclei revealed that the inhibitor I chromatin structure was highly sensitive to the enzyme compared to the inactive ribosomal chromatin. This sensitivity was independent of wounding. Digestion of tomato nuclei with micrococcal nuclease, which produces a nucleosomal ladder from bulk chromatin in agarose gels, supported these observations. Micrococcal nuclease produced only a faint nucleosomal repeat superimposed on a smear for the coding region of the inhibitor I gene, whereas digestion of inactive ribosomal chromatin produced a well defined nucleosomal ladder. Two DNase I-hypersensitive sites were found in the promoter region of the inhibitor I gene. Both were present before and after wound induction. These two constitutive DNase I-hypersensitive sites may correspond to DNA regulatory regions of the gene. The combined results indicate the existence of an open chromatin conformation in the inhibitor I gene DNA region, present before gene induction by wounding.
Conconi
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Institute of Biological Chemistry, Washington State University, Pullman 99164-6340.
Ryan
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D002458:Cell Fractionation; D002467:Cell Nucleus / Q000502:physiology / Q000648:ultrastructure; D002499:Centrifugation, Density Gradient; D002843:Chromatin / Q000502:physiology*; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D003850:Deoxyribonuclease I; D017343:Genes, Plant; D008836:Micrococcal Nuclease; D010940:Plant Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011480:Protease Inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D014158:Transcription, Genetic
D002843:Chromatin; D010940:Plant Proteins; D011480:Protease Inhibitors; D012333:RNA, Messenger; C023578:proteinase inhibitor I (plants); D004247:DNA; D003850:Deoxyribonuclease I; D008836:Micrococcal Nuclease