Vincent, Susan, and colleagues published Vincent’s thesis work on the structure of an archaeal box C/D s(no)RNP! Using cryo-electron microscopy (cryo-EM), their 9.0 ångström structure revealed a parallel orientation of the two small RNAs within the ribonucleoprotein complex, and provide support for a stabilizing interaction between the RNA stem ends. This structure is the first cryo-EM structure to be solved at sub-nanometer resolution here at Yale!
Check out the original research here in Nucleic Acids Research: https://doi.org/10.1093/nar/gkw576
Box C/D sRNA stem ends act as stabilizing anchors for box C/D di-sRNPs
Ribosomal RNA (rRNA) modifications are essential for ribosome function in all cellular organisms. Box C/D small (nucleolar) ribonucleoproteins [s(no)RNPs] catalyze 2’-O-methylation, one rRNA modification type in Eukarya and Archaea. Negatively stained electron microscopy (EM) models of archaeal box C/D sRNPs have demonstrated the dimeric sRNP (di-sRNP) architecture, which has been corroborated by nuclear magnetic resonance (NMR) studies. Due to limitations of the structural techniques, the orientation of the box C/D sRNAs has remained unclear. Here, we have used cryo-EM to elucidate the sRNA orientation in a M. jannaschii box C/D di-sRNP. The cryo-EM reconstruction suggests a parallel orientation of the two sRNAs. Biochemical and structural analyses of sRNPs assembled with mutant sRNAs indicate a potential interaction between the sRNA stem ends. Our results suggest that the parallel arrangement of the sRNAs juxtaposes their stem ends into close proximity to allow for a stabilizing interaction that helps maintain the di-sRNP architecture.