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Molecular mechanism for dimerization to regulate the catalytic activity of human cytomegalovirus protease

Nature Structural Biology volume 8, pages 810817 (2001) | Download Citation

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Abstract

Biochemical studies indicate that dimerization is required for the catalytic activity of herpesvirus proteases, whereas structural studies show a complete active site in each monomer, away from the dimer interface. Here we report kinetic, biophysical and crystallographic characterizations of structure-based mutants in the dimer interface of human cytomegalovirus (HCMV) protease. Such mutations can produce a 1,700-fold reduction in the kcat while having minimal effects on the Km. Dimer stability is not affected by these mutations, suggesting that dimerization itself is insufficient for activity. There are large changes in monomer conformation and dimer organization of the apo S225Y mutant enzyme. However, binding of an activated peptidomimetic inhibitor induced a conformation remarkably similar to the wild type protease. Our studies suggest that appropriate dimer formation may be required to indirectly stabilize the protease oxyanion hole, revealing a novel mechanism for dimerization to regulate enzyme activity.

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Acknowledgements

We thank R. Olson for help with analytical ultracentrifugation experiments; C. Parish for help with CD measurements; M. Bailey for the synthesis of BILC408; Y. Xu, Z. Yang, C. Ogata and J. Berendzen for help with data collection at the synchrotron radiation source; W.W. Cleland for helpful discussions and the National Institutes of Health (grant to L.T.) for financial support. R.K. is supported by the training program in molecular biophysics.

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  1. Department of Biological Sciences, Columbia University, New York, New York 10027, USA.

    • Renu Batra
    • , Reza Khayat
    •  & Liang Tong

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Correspondence to Liang Tong.

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https://doi.org/10.1038/nsb0901-810

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