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Insights into copper coordination in the EcoRI-DNA complex by ESR spectroscopy.

ABSTRACT: The EcoRI restriction endonuclease requires one divalent metal ion in each of two symmetrical and identical catalytic sites to catalyse double-strand DNA cleavage. Recently, we showed that Cu(2+) binds outside the catalytic sites to a pair of new sites at H114 in each sub-unit, and inhibits Mg(2+) -catalysed DNA cleavage. In order to provide more detailed structural information on this new metal ion binding site, we performed W-band (~94 GHz) and X-band (~9.5 GHz) electron spin resonance spectroscopic measurements on the EcoRI-DNA-(Cu(2+) )2 complex. Cu(2+) binding results in two distinct components with different gzz and Azz values. X-band electron spin echo envelope modulation results indicate that both components arise from a Cu(2+) coordinated to histidine. This observation is further confirmed by the hyperfine sub-level correlation results. W-band electron nuclear double resonance spectra provide evidence for equatorial coordination of water molecules to the Cu(2+) ions.

SUBMITTER: Ji M

PROVIDER: S-EPMC4350447 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Insights into copper coordination in the EcoRI-DNA complex by ESR spectroscopy.

Ji Ming M Tan Likun L Jen-Jacobson Linda L Saxena Sunil S

Molecular physics 20141201 24

The EcoRI restriction endonuclease requires one divalent metal ion in each of two symmetrical and identical catalytic sites to catalyse double-strand DNA cleavage. Recently, we showed that Cu2+ binds outside the catalytic sites to a pair of new sites at H114 in each sub-unit, and inhibits Mg2+ -catalysed DNA cleavage. In order to provide more detailed structural information on this new metal ion binding site, we performed W-band (~94 GHz) and X-band (~9.5 GHz) electron spin ...[more]

PMID: 25750461

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