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.
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.
Alexciev
K
K
Department of Molecular Genetics, Karolinska Institutet, Stockholm, Sweden.
Wurtz
T
T
Lönnroth
A
A
Daneholt
B
B
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
D012322:RNA Precursors; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D012259:Ribonuclease, Pancreatic