title: Genes transcribed at diverse rates have a similar conformation in chromatin.
abstract: We have analyzed the DNA generated upon treatment of oviduct nuclei with pancreatic DNase I (deoxyribonucleate 3'-oligonucleotidohydrolase; EC 3.1.4.6), with cDNA copies of specific mRNA sequences to study the structure and organization of transcriptionally active genes in chromatin. In this report we examine the kinetics of digestion of three classes of genes in the oviduct which are transcribed at significantly different rates. Our results indicate that the ovalbumin genes appear to be organized by chromatin proteins in such a way that they are rendered exceedingly sensitive to digestion by DNase I. This sensitivity is not observed in the liver, a tissue in which these genes are transcriptionally inert. Furthermore, the transcriptionally inactive globin genes in the oviduct are not selectively sensitive to nuclease attack and are digested 5 times more slowly in the ovalbumin genes in this tissue. In addition, we have examined the accessibility of a complex subset of genes that are rarely represented in the mRNA and are likely to be transcribed at a frequency orders of magnitude below that of the ovalbumin gene. Comparison of the accessibility of these sequences with that of the ovalbumin gene indicates that these two subsets of genes are recognized and cleaved by DNase I at similar rates. These results suggest that the maintenance of an active conformation about specific genes does not reflect the polymerase distribution about these genes. This active conformation is therefore not confined to sequences actively engaged in the transcription process and may reflect the structure about a subpopulation of the genome which represents the transcriptional potential of a given cell type.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000032:analysis; D002645:Chickens; D002843:Chromatin / Q000032:analysis; D004247:DNA / Q000032:analysis / Q000096:biosynthesis / Q000302:isolation & purification; D003851:Deoxyribonucleases / Q000378:metabolism; D005260:Female; D005796:Genes; D006868:Hydrolysis; D066298:In Vitro Techniques; D007700:Kinetics; D009690:Nucleic Acid Conformation; D010057:Oviducts / Q000648:ultrastructure; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D012333:RNA, Messenger; D004247:DNA; D003851:Deoxyribonucleases
references.citation: Nucleic Acids Res. 1977 Jan;4(1):71-84
references.pmid: 866179
references.citation: Cell. 1977 Mar;10(3):415-32
references.pmid: 844101
references.citation: Ann N Y Acad Sci. 1977 Mar 11;286:135-46
references.pmid: 281170
references.citation: Nucleic Acids Res. 1977 Apr;4(4):883-98
references.pmid: 866196
references.citation: Cell. 1976 Jun;8(2):305-19
references.pmid: 822943
references.citation: Proc Natl Acad Sci U S A. 1976 Nov;73(11):3966-70
references.pmid: 1069279
references.citation: Cell. 1976 Nov;9(3):409-17
references.pmid: 991271
references.citation: Cell. 1976 Sep;9(1):131-46
references.pmid: 975237
references.citation: Proc Natl Acad Sci U S A. 1973 Dec;70(12):3440-2
references.pmid: 4587253
references.citation: Proc Natl Acad Sci U S A. 1973 Jul;70(7):2029-32
references.pmid: 4516203
references.citation: Biochim Biophys Acta. 1974 Jun 27;353(2):185-92
references.pmid: 4858315
references.citation: Proc Natl Acad Sci U S A. 1974 Aug;71(8):3045-9
references.pmid: 4370472
references.citation: Proc Natl Acad Sci U S A. 1975 Oct;72(10):3978-82
references.pmid: 1060078
references.citation: Science. 1976 Sep 3;193(4256):848-56
references.pmid: 948749
references.citation: Cell. 1976 Mar;7(3):455-65
references.pmid: 181146
references.citation: J Biol Chem. 1976 Jan 25;251(2):524-9
references.pmid: 1245487
references.citation: Cell. 1975 Jan;4(1):1-9
references.pmid: 1090375
references.citation: Cell. 1975 Mar;4(3):189
references.pmid: 1091360
references.citation: Proc Natl Acad Sci U S A. 1976 May;73(5):1572-5
references.pmid: 1064026
references.citation: Cell. 1976 Feb;7(2):247-54
references.pmid: 954082
references.citation: Proc Natl Acad Sci U S A. 1975 Nov;72(11):4404-8
references.pmid: 1060119