Ferguson ZNF Sandbox: Difference between revisions
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==The Zinc Finger== | ==The Zinc Finger== | ||
The DNA-binding motif known as the zinc finger was first discovered by Klug in Transcription Factor IIIA in ''Xenopus laevis'', the African clawed toad. TFIIIA is a 344 residue protein that contains 9 repeated modules, which are about 30 residues each, that contain two invariant | The DNA-binding motif known as the zinc finger was first discovered by Klug in Transcription Factor IIIA in ''Xenopus laevis'', the African clawed toad. TFIIIA is a 344 residue protein that contains 9 repeated modules, which are about 30 residues each, that contain <scene name='Zinc_Fingers/Zinc_fingers_cys/3'>two invariant cysteines</scene> and <scene name='Zinc_Fingers/Zinc_fingers_his/4'>two invariant histidines</scene><ref>Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. Fundamentals of Biochemistry: Life at the Molecular Level. 3rd Ed. Hoboken, NJ: Wiley, 2008</ref>. These are able to bind a zinc ion, allowing the protein to fold tightly around it. This protein stabilizer is found in thousands of different proteins in both plants and animals, but not in prokaryotic organisms. | ||
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[[Image:2adr.jpg|right|300px]]Two mutants in the N-terminal domain of ADR1, a yeast transcription factor that contains two Cys2-His2 zinc finger sequences spanning residues 102-159 were studied at the Department of Biochemistry at the University of Washington<ref>Hoffman, R.C.; Horvath, S.J.; Klevit, R.E. Structures of DNA-binding mutant zinc finger domains: implications for DNA binding. Protein Sci. 1993 June; 2(6): 951–965.</ref>. The structure to the left shows the region responsible for DNA binding and contains two zinc fingers. Within this region, there are two point mutants at position 118 in the N-terminal zinc finger (ADR1b: 102-130) that adversely affect the DNA-binding activity of ADR1 that been identified: H118A and H118Y. Comparisons of wild-type ADR1b and the two mutants revealed that neither mutation causes a significant structural perturbation. The structures indicate that the DNA binding properties of the His 118 mutants are dependent on the identity of the side chain at position 118, which makes a direct DNA contact in the wild-type ADR1 protein. The results suggest that the identity of the side chain at the middle DNA contact position in Cys2-His2 zinc fingers may be changed regarding the domain structure and this change can and will affect the affinity of the protein-DNA interaction<ref>Hoffman, R.C.; Horvath, S.J.; Klevit, R.E. Structures of DNA-binding mutant zinc finger domains: implications for DNA binding. Protein Sci. 1993 June; 2(6): 951–965.</ref>. | [[Image:2adr.jpg|right|300px]]Two mutants in the N-terminal domain of ADR1, a yeast transcription factor that contains two Cys2-His2 zinc finger sequences spanning residues 102-159 were studied at the Department of Biochemistry at the University of Washington<ref>Hoffman, R.C.; Horvath, S.J.; Klevit, R.E. Structures of DNA-binding mutant zinc finger domains: implications for DNA binding. Protein Sci. 1993 June; 2(6): 951–965.</ref>. The structure to the left shows the region responsible for DNA binding and contains two zinc fingers. Within this region, there are two point mutants at position 118 in the N-terminal zinc finger (ADR1b: 102-130) that adversely affect the DNA-binding activity of ADR1 that been identified: H118A and H118Y. Comparisons of wild-type ADR1b and the two mutants revealed that neither mutation causes a significant structural perturbation. The structures indicate that the DNA binding properties of the His 118 mutants are dependent on the identity of the side chain at position 118, which makes a direct DNA contact in the wild-type ADR1 protein. The results suggest that the identity of the side chain at the middle DNA contact position in Cys2-His2 zinc fingers may be changed regarding the domain structure and this change can and will affect the affinity of the protein-DNA interaction<ref>Hoffman, R.C.; Horvath, S.J.; Klevit, R.E. Structures of DNA-binding mutant zinc finger domains: implications for DNA binding. Protein Sci. 1993 June; 2(6): 951–965.</ref>. | ||
