Methanopyrus kandleri is a hyperthermophilic methanogenic archaeon, which grows on H2 and CO2 as its sole energy source. Its growth temperature optimum is 98°C. One of the interesting characteristics of this archaeon is its high intracellular salt content. The organism has been reported to contain the trianionic cDPG (cyclic 2,3-diphosphoglycerate) and K+ at concentrations of 1.1 and 3 M, respectively. Reflecting the high cellular salt concentration, the enzymes in this organism are adapted not only to high temperature but also to high salt concentrations. The formyltransferase from M. kandleri was characterized extensively with respect to thermo- and halophilicity. The crystal structure of the formyltransferase at 1.73 Å shows the enzyme to be composed of four identical subunits of molecular mass 32 kDa. The formyltransferase is thermostable and active only at relatively high concentrations of potassium phosphate (1 M) or other salts with strongly hydrated anions (strong salting-out salts). Potassium phosphate and potassium cDPG were found to be equivalent in activating and stabilizing the enzyme. At low concentrations of these salts, the enzyme is inactive and thermolabile. It was shown by equilibrium sedimentation analysis that the enzyme is in a monomer/dimer/tetramer equilibrium, the equilibrium constant being dependent on the concentration of salts: the higher oligomeric species increase with increasing salt concentrations. Evidence was provided that the monomer is both inactive and thermolabile. Experiments using a mutation which is directed to break surface ion pairs between two dimers indicated that dimerization is required for activity and tetramerization leads to thermostability.
Conference Article| April 01 2004
Hyperthermophilic and salt-dependent formyltransferase from Methanopyrus kandleri
S. Shima 1
*Max-Planck-Institut für terrestrische Mikrobiologie and Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch Strasse, 35043 Marburg, Germany
1To whom correspondence should be addressed (e-mail firstname.lastname@example.org).
Search for other works by this author on:
Biochem Soc Trans (2004) 32 (2): 269-272.
- Views Icon Views
- Share Icon Share
- Cite Icon Cite
S. Shima, R.K. Thauer, U. Ermler; Hyperthermophilic and salt-dependent formyltransferase from Methanopyrus kandleri. Biochem Soc Trans 1 April 2004; 32 (2): 269–272. doi: https://doi.org/10.1042/bst0320269
Download citation file: