TY - JOUR
T1 - The kinetic mechanism of phosphomevalonate kinase
AU - Pilloff, Daniel
AU - Dabovic, Kristina
AU - Romanowski, Michael J.
AU - Bonanno, Jeffrey B.
AU - Doherty, Mary
AU - Burley, Stephen K.
AU - Leyh, Thomas S.
PY - 2003/2/14
Y1 - 2003/2/14
N2 - 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.
AB - 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.
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U2 - 10.1074/jbc.M210551200
DO - 10.1074/jbc.M210551200
M3 - Article
C2 - 12424232
AN - SCOPUS:0038813754
SN - 0021-9258
VL - 278
SP - 4510
EP - 4515
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 7
ER -