7MKT

Crystal structure of r(GU)11G-NMM complex

Summary for 7MKT

• Entry DOI: 10.2210/pdb7mkt/pdb
• Descriptor: RNA (5'-R(*GP*UP*GP*UP*GP*UP*GP*UP*GP*UP*GP*UP*GP*UP*GP*UP*GP*UP*GP*UP*GP*UP*G)-3'), N-METHYLMESOPORPHYRIN, POTASSIUM ION (3 entities in total)
• Functional Keywords: rna-porpyrin complex, rna
• Biological source: synthetic construct
• Total number of polymer chains: 1
• Total formula weight: 8280.64

Authors

Bingman, C.A.,Roschdi, S.,Nomura, Y.,Butcher, S.E. (deposition date: 2021-04-26, release date: 2022-11-02, Last modification date: 2024-05-22)

Primary citation

Roschdi, S.,Yan, J.,Nomura, Y.,Escobar, C.A.,Petersen, R.J.,Bingman, C.A.,Tonelli, M.,Vivek, R.,Montemayor, E.J.,Wickens, M.,Kennedy, S.G.,Butcher, S.E.
An atypical RNA quadruplex marks RNAs as vectors for gene silencing.
Nat.Struct.Mol.Biol., 29:1113-1121, 2022

PubMed Abstract: The addition of poly(UG) ('pUG') repeats to 3' termini of mRNAs drives gene silencing and transgenerational epigenetic inheritance in the metazoan Caenorhabditis elegans. pUG tails promote silencing by recruiting an RNA-dependent RNA polymerase (RdRP) that synthesizes small interfering RNAs. Here we show that active pUG tails require a minimum of 11.5 repeats and adopt a quadruplex (G4) structure we term the pUG fold. The pUG fold differs from known G4s in that it has a left-handed backbone similar to Z-RNA, no consecutive guanosines in its sequence, and three G quartets and one U quartet stacked non-sequentially. The compact pUG fold binds six potassium ions and brings the RNA ends into close proximity. The biological importance of the pUG fold is emphasized by our observations that porphyrin molecules bind to the pUG fold and inhibit both gene silencing and binding of RdRP. Moreover, specific 7-deaza substitutions that disrupt the pUG fold neither bind RdRP nor induce RNA silencing. These data define the pUG fold as a previously unrecognized RNA structural motif that drives gene silencing. The pUG fold can also form internally within larger RNA molecules. Approximately 20,000 pUG-fold sequences are found in noncoding regions of human RNAs, suggesting that the fold probably has biological roles beyond gene silencing.

PubMed: 36352138
DOI: 10.1038/s41594-022-00854-z

Experimental method

X-RAY DIFFRACTION (1.97 Å)