5S rRNA-assisted DnaK refolding.
Although accumulating evidence has revealed that most proteins can fold without the assistance of molecular chaperones, little attention has been paid to other types of chaperoning macromolecules. A variety of proteins interact with diverse RNA molecules in vivo, suggesting a potential role of RNAs for folding of their interacting proteins. Here we show that the in vitro refolding of a representative molecular chaperone, DnaK, an Escherichia coli homolog of Hsp70, could be assisted by its interacting 5S rRNA. The folding enhancement occurred in RNA concentration and its size dependent manner whereas neither the RNA with the reverse sequence of 5S rRNA nor the RNase pretreated 5S rRNA stimulated the folding in vitro. Based on our results, we propose that 5S rRNA could exert the chaperoning activity on DnaK during the folding process. The results suggest an interesting possibility that the folding of RNA-interacting proteins could be assisted by their cognate RNA ligands.
Kim
Hyo Kyung
HK
Department of Biotechnology, College of Bioscience and Biotechnology, Yonsei University, Seoul 120-749, South Korea.
Choi
Seong Il
SI
Seong
Baik L
BL
D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D009690:Nucleic Acid Conformation; D017510:Protein Folding; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000378:metabolism; D012341:RNA, Ribosomal, 5S / Q000737:chemistry / Q000378:metabolism*
D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D008024:Ligands; D012338:RNA, Ribosomal, 23S; D012341:RNA, Ribosomal, 5S; C063842:dnaK protein, E coli