A characterization of the low temperature structural transition of Escherichia coli 5 S RNA by partial enzymatic digestion.

The low temperature structural transition (low leads to high) of 5 S RNA from Escherichia coli is investigated by partial digestion with ribonuclease T1. In addition to a general masking of guanines from the nuclease, differential changes of accessibility are observed when Mg2+ and salt concentrations are increased to bring about the low leads to high transition. Residue G13 becomes more exposed in the high form while residues G54, G56, G61, G72, and G83-86 become less exposed. The observed cutting rate at other sites is unchanged. A possible conformational change is discussed which could explain the observed changes in RNase T1 digestion patterns as well as the physical chemical observations.