Evidence for the structural stability of ribonucleoprotein LMG(160) under ribonuclease-A treatment.

Low mobility group nonhistone protein, LMG(160), is a ribonucleoprotein particle of the nuclear matrix with an inhibitory effect on transcription. Through the current study, we have investigated comparatively the effect and behavior of the protein in the absence and presence of its RNA moiety. Analysis was performed with the intact LMG(160) and its RNase-treated form using native and denatured gel electrophoresis as well as fluorescence spectroscopy and trypsin digestion techniques. The results show that the RNA moiety of LMG(160) plays a key role in maintaining the overall structure and conformation of this RNP particle, in the way that RNA removal causes some alterations in the structural stability of the protein, leading it to become self-associated. This finding can easily explain the loss of function of LMG(160) after RNase-treatment, the effect that may influence the biological activity of the molecule in the nuclear matrix structure.