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Zinc Dependent Recognition of a Human CpG Island Sequence by the Mammalian Spermatidal Protein TP2

Kundu, Tapas Kumar and Manchanahalli, R and Rao, Satyanarayana (1996) Zinc Dependent Recognition of a Human CpG Island Sequence by the Mammalian Spermatidal Protein TP2. In: Biochemistry, 35 (49). pp. 15626-15632.

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Rat spermatidal protein TP2 is a zinc metalloprotein with two atoms of zinc coordinated to cysteine and histidine residues and condenses alternating GC copolymer preferentially in a zinc dependent manner [Kundu, T. K., & Rao, M. R. S. (1995) Biochemistry 34, 5143-5150]. In the present study, we have used a 40-mer oligonucleotide containing a human CpG island sequence to study its interaction with TP2 by gel mobility shift assays. A specific complex was observed in the presence of poly(dI). poly(dC). Preincubation of TP2 with 10 mM EDTA or 1 mM 1, 10-o-phenanthroline inhibited the complex formation by more than 90%. Competition experiments with various polynucleotides revealed the following order of efficiency: poly(dG-dC). poly(dG-dC) > cold homologous oligonucleotide > poly(dA-dT). poly(dA-dT). Homoduplexes poly(dG). poly(dC) and poly(dA). poly(dT) had no effect on the complex formation. Chromomycin A(3), a GC minor groove binding drug, inhibited the complex formation. Methylation of the CpG doublet within the CpG island sequence by SssI methylase (CpG methylase) completely abolished the complex formation. Methylation of G at the N-7 position with dimethyl sulfate did not affect the recognition of CpG island by TP2. Thus, CpG islands, widely distributed in the mammalian genome, may serve as specific loci for initiation of chromatin condensation by TP2 during the later stages of spermiogenesis

Item Type: Journal Article
Publication: Biochemistry
Publisher: American Chemical Society
Additional Information: Coyright of this article belongs to American Chemical Society.
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 27 Feb 2009 06:02
Last Modified: 19 Sep 2010 05:25
URI: http://eprints.iisc.ac.in/id/eprint/18893

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