skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Studies of DNA supercoiling in vivo and in vitro

Abstract

This thesis describes a number of diverse experiments whose common theme is to elaborate some aspect of DNA supercoiling. The torsion elastic constant of DNA is measure as a function of superhelix density using the technique of picosecond Time Resolved Fluorescence Polarization Anisotropy (FPA) of intercalated ethidium bromide. The results agree with theories which predict that the anisotropy decay should vary with the square root of the relative viscosity. This experiment furthermore demonstrates a sensitivity of FPA to a change in torsion elastic constant of less than 10%. A number of covalently closed DNA samples, ranging in superhelix density from = [minus]0.123 to [plus]0.042, are then examined. A novel method for measuring changes in local supercoiling on a large PNA molecule which is sensitive to changes in supercoiling of regions of chromosomal DNA as short as 1 kilobase in length is presented. Study of chromosomal supercoiling regulating anaerobic gene expression in the facultative photosynthetic bacterium, Rhodobacter capsulatus showed that no stable change in chromosomal supercoiling upon a shift from aerobic respiratory growth to anaerobic photosynthetic conditions. Studies to detect transient changes in DNA supercoiling indicate that DNA downstream from heavily transcribed genes for the photosynthetic reaction center are relaxed ormore » perhaps overwound upon the induction of photosynthetic metabolism. These results are interpreted in terms of the twin domain model of transcriptional supercoiling.« less

Authors:
Publication Date:
Research Org.:
Lawrence Berkeley Lab., CA (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
6993672
Report Number(s):
LBL-32809
ON: DE93002556
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CHROMOSOMES; MOLECULAR STRUCTURE; DNA; BIOPHYSICS; CONFORMATIONAL CHANGES; DNA HELICASES; ELASTICITY; FLUORESCENCE SPECTROSCOPY; GENE REGULATION; IN VITRO; IN VIVO; ISOMERASES; TORSION; TRANSCRIPTION; EMISSION SPECTROSCOPY; ENZYMES; MECHANICAL PROPERTIES; NUCLEIC ACIDS; ORGANIC COMPOUNDS; PROTEINS; SPECTROSCOPY; TENSILE PROPERTIES; 550200* - Biochemistry

Citation Formats

Cook, D.N.. Studies of DNA supercoiling in vivo and in vitro. United States: N. p., 1990. Web. doi:10.2172/6993672.
Cook, D.N.. Studies of DNA supercoiling in vivo and in vitro. United States. doi:10.2172/6993672.
Cook, D.N.. Mon . "Studies of DNA supercoiling in vivo and in vitro". United States. doi:10.2172/6993672. https://www.osti.gov/servlets/purl/6993672.
@article{osti_6993672,
title = {Studies of DNA supercoiling in vivo and in vitro},
author = {Cook, D.N.},
abstractNote = {This thesis describes a number of diverse experiments whose common theme is to elaborate some aspect of DNA supercoiling. The torsion elastic constant of DNA is measure as a function of superhelix density using the technique of picosecond Time Resolved Fluorescence Polarization Anisotropy (FPA) of intercalated ethidium bromide. The results agree with theories which predict that the anisotropy decay should vary with the square root of the relative viscosity. This experiment furthermore demonstrates a sensitivity of FPA to a change in torsion elastic constant of less than 10%. A number of covalently closed DNA samples, ranging in superhelix density from = [minus]0.123 to [plus]0.042, are then examined. A novel method for measuring changes in local supercoiling on a large PNA molecule which is sensitive to changes in supercoiling of regions of chromosomal DNA as short as 1 kilobase in length is presented. Study of chromosomal supercoiling regulating anaerobic gene expression in the facultative photosynthetic bacterium, Rhodobacter capsulatus showed that no stable change in chromosomal supercoiling upon a shift from aerobic respiratory growth to anaerobic photosynthetic conditions. Studies to detect transient changes in DNA supercoiling indicate that DNA downstream from heavily transcribed genes for the photosynthetic reaction center are relaxed or perhaps overwound upon the induction of photosynthetic metabolism. These results are interpreted in terms of the twin domain model of transcriptional supercoiling.},
doi = {10.2172/6993672},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Oct 01 00:00:00 EDT 1990},
month = {Mon Oct 01 00:00:00 EDT 1990}
}

Technical Report:

Save / Share: