| Autor: |
Ghering AB; Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA., Jenkins LM, Schenck BL, Deo S, Mayer RA, Pikaart MJ, Omichinski JG, Godwin HA |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2005 Mar 23; Vol. 127 (11), pp. 3751-9. |
| DOI: |
10.1021/ja0464544 |
| Abstrakt: |
GATA proteins are transcription factors that bind GATA DNA elements through Cys4 structural zinc-binding domains and play critical regulatory roles in neurological and urogenital development and the development of cardiac disease. To evaluate GATA proteins as potential targets for lead, spectroscopically monitored metal-binding titrations were used to measure the affinity of Pb2+ for the C-terminal zinc-binding domain from chicken GATA-1 (CF) and the double-finger domain from human GATA-1 (DF). Using this method, Pb2+ coordinating to CF and DF was directly observed through the appearance of intense bands in the near-ultraviolet region of the spectrum (250-380 nm). Absorption data collected from these experiments were best fit to a 1:1 Pb2+ -CF model and a 2:1 Pb2+ -DF model. Competition experiments using Zn2+ were used to determine the absolute affinities of Pb2+ for these proteins. These studies reveal that Pb2+ forms tight complexes with cysteine residues in the zinc-binding sites in GATA proteins, beta1Pb = 6.4 (+/- 2.0) x 10(9) M(-1) for CF and beta2 = 6.3 (+/- 6.3) x 10(19) M(-2) for Pb(2+)2-DF, and within an order of magnitude of the affinity of Zn2+ for these proteins. Furthermore, Pb2+ was able to displace bound Zn2+ from CF and DF. Upon addition of Pb2+, GATA shows a decreased ability to bind to DNA and subsequently activate transcription. Therefore, the DNA binding and transcriptional activity of GATA proteins are most likely to be targeted by Pb2+ in cells and tissues that sequester Pb2+ in vivo, which include the brain and the heart. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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