RNA Chaperone Activity Of Proteins Research Articles

Structural Investigations of RNA\u2013Protein Complexes in Post-Ribosomal Era

Structural studies of RNA–protein complexes are important for understanding many molecular mechanisms occurring in cells (e.g., regulation of protein synthesis and RNA-chaperone activity of proteins). Various objects investigated at the Institute of Protein Research of the Russian Academy of Sciences are considered. Based on the analysis of the structures of the complexes of the ribosomal protein L1 with specific regions on both mRNA and rRNA, the principles of regulation of the translation of the mRNA of its own operon are presented. The studies of the heterotrimeric translation initiation factor IF2 of archaea and eukaryotes are described, and the data on the interaction of glycyl-tRNA-synthetase with viral IRES are reported. The results of studying the interaction of RNA molecules with one of functionally important sites of the Hfq protein are presented, and the differences in the RNA-binding properties of the Hfq and archaeal Lsm proteins are revealed.

Assays for the RNA chaperone activity of proteins

Proteins with RNA chaperone activity promote RNA folding by loosening the structure of misfolded RNAs or by preventing their formation. How these proteins achieve this activity is still unknown, the mechanism is not understood and it is unclear whether this activity is always based on the same mechanism or whether different RNA chaperones use different mechanisms. To address this question, we compare and discuss in this paper a set of assays that have been used to measure RNA chaperone activity. In some assays, this activity is related to the acceleration of monomolecular reactions such as group I intron cis-splicing or anti-termination of transcription. Hereby, it is proposed that the proteins release the RNAs from folding traps, which represent the kinetic barriers during the folding process and involve the loosening of structural elements. In most assays, however, bimolecular reactions are monitored, which include the simple acceleration of annealing of two complementary RNAs, the turnover stimulation of ribozyme cleavage and group I intron trans-splicing. The acceleration of these reactions most probably involves the unfolding of structures that interfere with annealing or folding and may in addition provoke annealing by crowding. Most assays are performed in vitro, where conditions might differ substantially from intracellular conditions, and two assays have been reported that detect RNA chaperone activity in vivo.