title: The elementary RNP fiber--not the higher order structure--determines the all-or-none disintegration behaviour of Balbiani ring pre-messenger RNP particles upon RNase A treatment.
abstract: Balbiani ring premessenger ribonucleoprotein (RNP) particles are built from a 7-nm RNP fiber which is tightly folded into a ring-shaped RNP ribbon. Isolated particles are known to disintegrate in all-or-none fashion upon RNase A treatment. In the present study we investigated whether this mode of disintegration is dependent on an intact particle structure or is inherent in the 7-nm fiber. When treated at low ionic strength, the Balbiani ring (BR) particles lost their higher order structure and the 7-nm fiber was unpacked, as evidenced by sucrose gradient sedimentation and electron microscopy. When treated with RNase A, unfolded as well as intact particles disintegrated in the all-or-none fashion, with similar kinetics and without apparent intermediates. Proteinase K treatment, however, obliterated this pattern: the protein-free particle RNA degraded progressively. As the typical disintegration pattern of the particles was not altered by unfolding, but was lost by deproteinization, the all-or-none mode of disintegration is likely to be a property of the 7-nm RNP fiber.
authors.affiliation: Department of Molecular Genetics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Alexciev
authors.forename: T
authors.initials: T
authors.lastname: Wurtz
authors.forename: A
authors.initials: A
authors.lastname: Lönnroth
authors.forename: B
authors.initials: B
authors.lastname: Daneholt
mesh_terms: D000818:Animals; D002683:Chironomidae; D002875:Chromosomes / Q000648:ultrastructure*; D009994:Osmolar Concentration; D012322:RNA Precursors / Q000187:drug effects* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000187:drug effects* / Q000648:ultrastructure; D012259:Ribonuclease, Pancreatic; D012261:Ribonucleoproteins / Q000187:drug effects* / Q000648:ultrastructure
chemical_list: D012322:RNA Precursors; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D012259:Ribonuclease, Pancreatic