4B5R

SAM-I riboswitch bearing the H. marismortui K-t-7

Summary for 4B5R

• Entry DOI: 10.2210/pdb4b5r/pdb
• Descriptor: SAM-I RIBOSWITCH, S-ADENOSYLMETHIONINE, BARIUM ION, ... (4 entities in total)
• Functional Keywords: rna, riboswitch, k-turn
• Biological source: THERMOANAEROBACTER TENGCONGENSIS
• Total number of polymer chains: 1
• Total formula weight: 32927.42

Authors

Daldrop, P.,Lilley, D.M.J. (deposition date: 2012-08-07, release date: 2013-01-30, Last modification date: 2023-12-20)

Primary citation

Daldrop, P.,Lilley, D.M.J.
The Plasticity of a Structural Motif in RNA: Structural Polymorphism of a Kink Turn as a Function of its Environment.
RNA, 19:357-, 2013

PubMed Abstract: The k-turn is a widespread structural motif that introduces a tight kink into the helical axis of double-stranded RNA. The adenine bases of consecutive G•A pairs are directed toward the minor groove of the opposing helix, hydrogen bonding in a typical A-minor interaction. We show here that the available structures of k-turns divide into two classes, depending on whether N3 or N1 of the adenine at the 2b position accepts a hydrogen bond from the O2' at the -1n position. There is a coordinated structural change involving a number of hydrogen bonds between the two classes. We show here that Kt-7 can adopt either the N3 or N1 structures depending on environment. While it has the N1 structure in the ribosome, on engineering it into the SAM-I riboswitch, it changes to the N3 structure, resulting in a significant alteration in the trajectory of the helical arms.

PubMed: 23325110
DOI: 10.1261/RNA.036657.112

Experimental method

X-RAY DIFFRACTION (2.95 Å)