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Structural mimicry in the phage φ21 N peptide–boxB RNA complex

Authors
  • CHRISTOPHER D. CILLEY
  • JAMES R. WILLIAMSON
Publisher
Copyright 2003 by RNA Society
Publication Date
Jun 01, 2003
Source
PMC
Keywords
Disciplines
  • Biology
License
Unknown

Abstract

We determined the solution structure of a 22-amino-acid peptide from the amino-terminal domain of the bacteriophage φ21 N protein in complex with its cognate 24-mer boxB RNA hairpin using heteronuclear magnetic resonance spectroscopy. The N peptide binds as an α-helix and interacts predominately with the major groove side of the 5′ half of the boxB RNA stem-loop. This binding interface is defined by surface complementarity of polar and nonpolar interactions, and little sequence-specific recognition. The φ21 boxB loop (CUAACC) has hydrogen bond and backbone torsions typical of the “U-turn” motif, as well as base stacking of the last 4 nt, and a hydrogen bonded C:C pair closing the loop. The exposed face of the φ21 boxB loop, in complex with the N peptide, is strikingly similar to the GNRA tetraloop-like folds of the related λ and P22 bacteriophage N peptide–boxB RNA complexes. The N peptide–boxB complexes of the various phage, while individually distinct, provide similar structural features for interactions with the Escherichia coli host factors to enable antitermination.

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