National Institutes of Health/National Human Genome Research Institute (NIH/NHGRI)
P41GM103832
米国
National Institutes of Health/National Human Genome Research Institute (NIH/NHGRI)
R01GM079429
米国
National Institutes of Health/National Human Genome Research Institute (NIH/NHGRI)
S10OD021600
米国
引用
ジャーナル: Nat Commun / 年: 2019 タイトル: Cryo-EM structure of a 40 kDa SAM-IV riboswitch RNA at 3.7 Å resolution. 著者: Kaiming Zhang / Shanshan Li / Kalli Kappel / Grigore Pintilie / Zhaoming Su / Tung-Chung Mou / Michael F Schmid / Rhiju Das / Wah Chiu / 要旨: Specimens below 50 kDa have generally been considered too small to be analyzed by single-particle cryo-electron microscopy (cryo-EM). The high flexibility of pure RNAs makes it difficult to obtain ...Specimens below 50 kDa have generally been considered too small to be analyzed by single-particle cryo-electron microscopy (cryo-EM). The high flexibility of pure RNAs makes it difficult to obtain high-resolution structures by cryo-EM. In bacteria, riboswitches regulate sulfur metabolism through binding to the S-adenosylmethionine (SAM) ligand and offer compelling targets for new antibiotics. SAM-I, SAM-I/IV, and SAM-IV are the three most commonly found SAM riboswitches, but the structure of SAM-IV is still unknown. Here, we report the structures of apo and SAM-bound SAM-IV riboswitches (119-nt, ~40 kDa) to 3.7 Å and 4.1 Å resolution, respectively, using cryo-EM. The structures illustrate homologies in the ligand-binding core but distinct peripheral tertiary contacts in SAM-IV compared to SAM-I and SAM-I/IV. Our results demonstrate the feasibility of resolving small RNAs with enough detail to enable detection of their ligand-binding pockets and suggest that cryo-EM could play a role in structure-assisted drug design for RNA.