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Investigation of the inhibitory role of phosphorothioate internucleotidic linkages on the catalytic activity of the restriction endonuclease EcoRV.

Abstract：

:The inhibitory effect of phosphorothioate residues, located within one strand of double-stranded DNA, on the hydrolytic activity of the restriction endonuclease EcoRV was investigated. Specific incorporation of a phosphorothioate group at the site of cleavage yielded the sequence 5'-GATsATC-3'. This modified sequence was cleaved at a relative rate of 0.1 compared to the unmodified substrate. Substrates 5'-GATsAsTC-3' and 5'-GsATsATC-3', both containing one additional phosphorothioate substitution, were linearized at a rate of 0.04 relative to unmodified DNA. However, under the same conditions, fully dAMPS-substituted DNA was found to be virtually resistant to the hydrolytic activity of EcoRV. Further experiments showed that double-stranded DNA fragments generated by PCR containing phosphorothioate groups within both strands are potent inhibitors of EcoRV catalysis. The inhibition was independent of whether the inhibitor fragment contained an EcoRV recognition site. We concluded that substitution of the phosphate group at the site of cleavage by a phosphorothioate residue decreases the rate of EcoRV-catalyzed hydrolysis most significantly. Substitution of other phosphate groups within the recognition sequence plays a limited role in enzyme inhibition. The presence of multiple dNMPS residues at regions of the DNA removed from the EcoRV recognition site may decrease the amount of enzyme available for catalysis by nonspecific binding to EcoRV.

journal_name

Biochemistry

journal_title

Biochemistry

authors

Olsen DB,Kotzorek G,Eckstein F

doi

10.1021/bi00493a008

subject

Has Abstract

pub_date

1990-10-16 00:00:00

pages

9546-51

issue

41

eissn

0006-2960

issn

1520-4995

journal_volume

29

pub_type

杂志文章

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