1xj9
From Proteopedia
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Crystal structure of a partly self-complementary peptide nucleic acid (PNA) oligomer showing a duplex-triplex network
Overview
The X-ray structure of a partly self-complementary peptide nucleic acid, (PNA) decamer (H-GTAGATCACT-l-Lys-NH(2)) to 2.60 A resolution is reported., The structure is mainly controlled by the canonical Watson-Crick base, pairs formed by the self-complementary stretch of four bases in the middle, of the decamer (G(4)A(5)T(6)C(7)). One right- and one left-handed, Watson-Crick duplex are formed. The two PNA units C(9)T(10) change helical, handedness, so that each PNA strand contains both a right- and a, left-handed section. The changed handedness in C(9)T(10) allows formation, of Hoogsteen hydrogen bonding between C(9)T(10) and G(4)A(5) of a PNA, strand in an adjacent Watson-Crick double helix of the same handedness., Thereby, a PNA-PNA-PNA triplex is formed. The PNA unit A(3) forms a, noncanonical base pair with A(8) in a symmetry-related strand of opposite, handedness; the base pair is of the A-A reverse Hoogsteen type. The, structural diversity of this PNA demonstrates how the PNA backbone is able, to adapt to structures governed by the stacking and hydrogen-bonding, interactions between the nucleobases. The crystal structure further shows, how PNA oligomers containing limited sequence complementarity may form, complex hydrogen-bonding networks.
About this Structure
1XJ9 is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Crystal structure of a partly self-complementary peptide nucleic acid (PNA) oligomer showing a duplex-triplex network., Petersson B, Nielsen BB, Rasmussen H, Larsen IK, Gajhede M, Nielsen PE, Kastrup JS, J Am Chem Soc. 2005 Feb 9;127(5):1424-30. PMID:15686374
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