Zinc Fingers DNA- and RNA-Binding Motifs

Among the strong preferences which have been observed, it seems that Arg prefers binding to guanosine. Asp to adenosine and cytosine, and Leu to thymidine. However, we are not yet sufficiently advanced to define a set of coding mles (i.e., to define the amino acid sequence of one or more zinc fingers which would bind to a specific DNA sequence). 

The Xenopus transcription factor lllA not only acts as an essential RNA polymerase transcription factor for the expression of the 5S rRNA gene, it also binds to the 5S rRNA to form a 7S ribonucleoprotein particle which stabilises the RNA until it is required for ribosome assembly and facihtates nuclear export of the 5S rRNA. Indeed, it was originally shown to be the protein component associated with 5S rRNA in the 7S particle in Xenopus oocytes before it was recognised as a transcription factor. How, we may ask, can this protein not only recognise specific DNA sequences in the 5S rRNA gene upstream region, but also recognise different, but equally specific, sequences in 5S rRNA  

Both biochemical and X-ray crystallographic data show that binding of TFlll A to the 5S rRNA gene internal control region utilises all but the fourth and sixth of the nine zinc fingers of the transcription factor 

FIGURE 12.20 (a) TFIIIA binds to 5S rRNA promoter sequences using zinc fingers 1—3, 5, and 7—9 which recognise respectively box C 

(2001). Zinc coordination sphere in biochemical zinc sites. BioMetals, 14, 271—313. 

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Multinuclear and Cocatalytic Zinc Enzymes.. . Zinc Fingers - DNA- and RNA-Binding Motifs References. 

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