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From Proteopedia
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DNA Zinc-finger 1
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Origin
Zinc fingers were first identified in a study of transcription in the transcription factor TFIIIA of the African clawed frog, Xenopus laevis, conducted in the lab of Aaron Klug, a Nobel Prize Winner known for electron crystallography.
Structure
The “finger” refers to the secondary structures ( and ) that are held together by the .
Proteins usually require many amino acids so that there would be enough hydrogen bonding and other interactions to form their secondary, tertiary, and quaternary structures. However, the polypeptide chains in zinc fingers can fold tightly around a zinc ion allowing a short chain of 20-30 amino acids to be enough to create a solid, stable structure.
Function
This small protein motif is a transcriptional regulator that regulates eukarotic gene expression. It recognizes and binds to the DNA sequence 5'-CGCCCCCGC-3', or EGR-site. DNA Zinc-fingers activate the transcription of target genes with products that are needed for mitogenesis (the induction of mitosis) and differentiation by interacting with several different transcription signals located in the ribosomal 5S RNA gene promoter of DNA.
Interactions
Zinc fingers are found in eukaryotic nucleus interacting with the outside of B-DNA. When interacting with DNA, the residue of the alpha helices in the zinc fingers bind in the major groove of B-DNA and wrap part way around the double helix, extending amino acids inwards to read the bases. A single zinc finger does not bind very tightly to the DNA and can only recognize 2 or 3 base pairs. However, when several are strung together, the group can bind more tightly and can read longer DNA sequences.
References
Zinc Fingers. (n.d.). Retrieved February 08, 2017, from http://www.ebi.ac.uk/interpro/potm/2007_3/Page2.htm
Miller, J., McLachlan, A. D., & Klug, A. (1985, June). Repetitive zinc-binding domains in the protein transcription factor IIIA from Xenopus oocytes. Retrieved February 08, 2017, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC554390/
Group, P. F., Motif, A., E., Highlights, C., & G. (n.d.). EpiGenie Learning Center. Retrieved February 08, 2017, from http://epigenie.com/key-epigenetic-players/chromatin-modifying-and-dna-binding-proteins/zinc-finger-proteins/
RCSB Protein Data Bank, Pavletich, N.P., Pabo, C.O. (n.d.). 1ZAA. Retrieved February 08, 2017, from http://www.rcsb.org/pdb/explore.do?structureId=1ZAA
PDB-101: Zinc Fingers. (n.d.). Retrieved February 08, 2017, from https://pdb101.rcsb.org/motm/871ZAA: Zinc Finger-dna Recognition: Crystal
1ZAA: Zinc Finger-dna Recognition: Crystal Structure of a Zif268- DNA Complex at 2.1 Angstroms - NCBI structure. (n.d.). Retrieved February 14, 2017, from https://www.ncbi.nlm.nih.gov/Structure/mmdb/mmdbsrv.cgi?uid=52204&Dopt=s
