The P-box refers to a sequence of three amino acids in the first zinc finger, which is involved in DNA sequence recognition. These similarities define a signature sequence shared by members of the family. The DNA-binding domain includes two so-called zinc fingers, in which four cysteines coordinate one zinc atom, and folds into a finger-like structure. Families of transcription regulators share a type of DNA-binding motif, as well as inducer binding or oligomerization motifs. “Our best case is now approaching nature's worst case,” says Romesberg. In molecular biology, a library is a collection of DNA fragments that is stored and propagated in a population of micro-organisms through the process of molecular cloning. Such interactions may involve DNA-binding motifs other than the HTH or factors, as used by B.subtilis for differentiation. 11), overlapping with the sloppiest rate for natural DNA. > The helix-turn-helix motif is a DNA binding motif composed of two -helices, which make contacts with DNA and are joined by a short turn. Any such protein is called DNA-binding protein. Examples are leucine zipper and zinc finger protein s. And in July, Romesberg's team reported rates of 99.66–99.99% for optimized versions of his bases, called NaM and 5SICS (ref. DNA binding motif: Common sites on different proteins which facilitate their binding to DNA. The same year, Benner and his colleagues showed that another unnatural base pair - P and Z, which join using hydrogen bonds - achieved fidelity of 99.8% per replication 10. In 2011, Hirao's team reported that DNA containing an unnatural hydrophobic base pair, called Ds and Diol1-Px, could be copied with 99.77–99.92% fidelity per replication 9. Hirao and his colleagues found that they could reduce mispairing by designing shapes that fit awkwardly with natural bases, and by adding negatively charged or electron-rich chemical groups that repel the natural bases' corresponding parts. Ichiro Hirao, a chemist at the RIKEN Systems and Structural Biology Center in Yokohama, Japan, had been intrigued by the idea of creating unnatural bases ever since reading James Watson's 1968 book The Double Helix as a teenager.
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