4xno

Crystal structure of 5'-CTTATPPPZZZATAAG

spinqualitylabelsall models 4xno, resolution 1.98Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4xno is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: 1W5, 1WA, BRU Related: 4xo0, 4xpc, 4xpe Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Expanded genetic systems are most likely to work with natural enzymes if the added nucleotides pair with geometries that are similar to those displayed by standard duplex DNA. Here, we present crystal structures of 16-mer duplexes showing this to be the case with two nonstandard nucleobases (Z, 6-amino-5-nitro-2(1H)-pyridone and P, 2-amino-imidazo[1,2-a]-1,3,5-triazin-4(8H)one) that were designed to form a Z:P pair with a standard "edge on" Watson-Crick geometry, but joined by rearranged hydrogen bond donor and acceptor groups. One duplex, with four Z:P pairs, was crystallized with a reverse transcriptase host and adopts primarily a B-form. Another contained six consecutive Z:P pairs; it crystallized without a host in an A-form. In both structures, Z:P pairs fit canonical nucleobase hydrogen-bonding parameters and known DNA helical forms. Unique features include stacking of the nitro group on Z with the adjacent nucleobase ring in the A-form duplex. In both B- and A-duplexes, major groove widths for the Z:P pairs are approximately 1 A wider than those of comparable G:C pairs, perhaps to accommodate the large nitro group on Z. Otherwise, ZP-rich DNA had many of the same properties as CG-rich DNA, a conclusion supported by circular dichroism studies in solution. The ability of standard duplexes to accommodate multiple and consecutive Z:P pairs is consistent with the ability of natural polymerases to biosynthesize those pairs. This, in turn, implies that the GACTZP synthetic genetic system can explore the entire expanded sequence space that additional nucleotides create, a major step forward in this area of synthetic biology. Structural basis for a six nucleotide genetic alphabet.,Georgiadis MM, Singh I, Kellett WF, Hoshika S, Benner SA, Richards NG J Am Chem Soc. 2015 Jun 3;137(21):6947-55. doi: 10.1021/jacs.5b03482. Epub 2015, May 18. PMID:25961938 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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