title: Protamine-induced condensation and decondensation of the same DNA molecule.
abstract: The DNA in sperm and certain viruses is condensed by arginine-rich proteins into toroidal subunits, a form of packaging that inactivates their entire genome. Individual DNA molecules were manipulated with an optical trap to examine the kinetics of torus formation induced by the binding of protamine and a subset of its DNA binding domain, Arg6. Condensation and decondensation experiments with lambda-phage DNA show that toroid formation and stability are influenced by the number of arginine-rich anchoring domains in protamine. The results explain why protamines contain so much arginine and suggest that these proteins must be actively removed from sperm chromatin after fertilization.
authors.affiliation: Electronics Engineering Technologies Division, Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Brewer
authors.forename: M
authors.initials: M
authors.lastname: Corzett
authors.forename: R
authors.initials: R
authors.lastname: Balhorn
mesh_terms: D001120:Arginine / Q000737:chemistry / Q000378:metabolism; D010582:Bacteriophage lambda; D001583:Benzoxazoles; D004279:DNA, Viral / Q000737:chemistry* / Q000378:metabolism*; D005456:Fluorescent Dyes; D007364:Intercalating Agents; D007834:Lasers; D008856:Microscopy, Fluorescence; D009690:Nucleic Acid Conformation; D011479:Protamines / Q000737:chemistry / Q000378:metabolism*; D011806:Quinolinium Compounds
chemical_list: D001583:Benzoxazoles; D004279:DNA, Viral; D005456:Fluorescent Dyes; D007364:Intercalating Agents; D011479:Protamines; D011806:Quinolinium Compounds; C075296:1,1'-((4,4,7,7-tetramethyl)-4,7-diazaundecamethylene)bis-4-(3-methyl-2,3-dihydro(benzo-1,3-oxazole)-2-methylidene)quinolinium; D001120:Arginine