A small, thermostable, and monofunctional chorismate mutase from the archaeon Methanococcus jannaschii

Biochemistry. 1998 Jul 14;37(28):10062-73. doi: 10.1021/bi980449t.


The gene for chorismate mutase (CM) from the archaeon Methanococcus jannaschii, an extreme thermophile, was subcloned and expressed in Escherichia coli. This gene, which belongs to the aroQ class of CMs, encodes a monofunctional enzyme (AroQf) able to complement the CM deficiency of an E. coli mutant strain. The purified protein follows Michaelis-Menten kinetics (kcat = 5.7 s-1 and Km = 41 microM at 30 degreesC) and displays pH-independent activity in the range of pH 5-9. Its activation parameters [Delta H = 16.2 kcal/mol, Delta S = -1. 7 cal/(mol.K)] are similar to those of another well characterized AroQ class CM, the mesophilic AroQp domain from E. coli. Like AroQp, the thermophilic CM is an alpha-helical dimer, but approximately 5 kcal/mol more stable than its mesophilic counterpart as judged from equilibrium denaturation studies. The possible origins of the thermostability of M. jannaschii AroQf, the smallest natural CM characterized to date, are discussed in light of available sequence and tertiary structural information.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Chorismate Mutase / chemistry*
  • Chorismate Mutase / genetics
  • Chorismate Mutase / metabolism
  • Chromatography, Gel
  • Circular Dichroism
  • Cloning, Molecular
  • Enzyme Stability
  • Genetic Complementation Test
  • Kinetics
  • Methanococcus / enzymology*
  • Methanococcus / genetics
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Denaturation
  • Protein Folding
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Sequence Analysis
  • Temperature


  • Recombinant Proteins
  • Chorismate Mutase