tailieunhanh - Báo cáo Y học: Ribosome-associated factor Y adopts a fold resembling a double-stranded RNA binding domain scaffold

Escherichia coliproteinY (pY) binds to the small ribosomal subunit and stabilizes ribosomes against dissociation when bacteria experience environmental stress. pY inhibits trans-lationin vitro,most probably by interferingwith the binding of the aminoacyl-tRNA to the ribosomal A site. Such a translational arrest may mediate overall adaptation of cells to environmental conditions. We have determined the 3D solution structure of a 112-residue pY and have studied its backbone dynamic by NMRspectroscopy. . | Eur. J. Biochem. 269 5182-5191 2002 FEBS 2002 doi Ribosome-associated factor Y adopts a fold resembling a double-stranded RNA binding domain scaffold Keqiong Ye1 Alexander Serganov1 Weidong Hu1 Maria Garber2 and Dinshaw J. Patel1 1 Cellular Biochemistry Biophysics Program Memorial Sloan-Kettering Cancer Center New York USA institute of Protein Research Moscow Region Pushchino Russia Escherichia coli protein Y pY binds to the small ribosomal subunit and stabilizes ribosomes against dissociation when bacteria experience environmental stress. pY inhibits translation in vitro most probably by interfering with the binding of the aminoacyl-tRNA to the ribosomal A site. Such a translational arrest may mediate overall adaptation of cells to environmental conditions. We have determined the 3D solution structure of a 112-residue pY and have studied its backbone dynamic by NMR spcclroscoyy. The tlruclure has a papppa topology and represents a compact twolayered sandwich of two nearly parallel a helices packed against the same side of a four-stranded p sheet. The 23 C-terminal residues of the protein are disordered. Long-range angular constraints provided by residual dipolar coupling data proved critical for precisely defining the position of helix 1. Our data establish that the C-terminal region of helix 1 and the loop linking this helix with strand p2 show significant conformational exchange in the ms is time scale which may have relevance to the interaction of pY with ribosomal subunits. Distribution of the conserved residues on the protein surface highlights a positively charged region towards the C-terminal segments of both a helices which most probably constitutes an RNA binding site. The observed papppa topology of pY resembles the apppa topology of double-stranded RNA-binding domains despite limited sequence similarity. It appears probable that functional properties of pY are not identical to those of dsRBDs as the postulated .