The kinetic mechanism of phosphomevalonate kinase

Daniel Pilloff, Kristina Dabovic, Michael J. Romanowski, Jeffrey B. Bonanno, Mary Doherty, Stephen K. Burley, Thomas S. Leyh

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Abstract

Phosphomevalonate kinase catalyzes an essential step in the so-called mevalonate pathway, which appears to be the sole pathway for the biosynthesis of sterols and other isoprenoids in mammals and archea. Despite the well documented importance of this pathway in the cause and prevention of human disease and that it is the biosynthetic root of an enormous diverse class of metabolites, the mechanism of phosphomevalonate kinase from any organism is not yet well characterized. The first structure of a phosphomevalonate kinase from Streptococcus pneumoniae was solved recently. The enzyme exhibits an atypical P-loop that is a conserved defining feature of the GHMP kinase superfamily. In this study, the kinetic mechanism of the S. pneumoniae enzyme is characterized in the forward and reverse directions using a combination of classical initial-rate methods including alternate substrate inhibition using ADPβS. The inhibition patterns strongly support that in either direction the substrates bind randomly to the enzyme prior to chemistry, a random sequential bi-bi mechanism. The kinetic constants are as follows: kcat(forward) = 3.4 s-1, Ki(ATp) = 137 μM, Km(ATP) = 74 μM, Ki(pmev) = 7.7 μM, Km(pmev) = 4.2 μM; kcat(reverse) = 3.9 s-1, Ki(ADP) = 410 μM, Km(ADP) = 350 μM, Ki(ppmev) = 14 μM, Km(ppmev) = 12 μM, where pmev and ppmev represent phosphomevalonate and diphosphomevalonate, respectively.

Original languageEnglish (US)
Pages (from-to)4510-4515
Number of pages6
JournalJournal of Biological Chemistry
Volume278
Issue number7
DOIs
StatePublished - Feb 14 2003

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Pilloff, D., Dabovic, K., Romanowski, M. J., Bonanno, J. B., Doherty, M., Burley, S. K., & Leyh, T. S. (2003). The kinetic mechanism of phosphomevalonate kinase. Journal of Biological Chemistry, 278(7), 4510-4515. https://doi.org/10.1074/jbc.M210551200