Opposite roles of domains 2+3 of Escherichia coli EF-Tu and Bacillus stearothermophilus EF-Tu in the regulation of EF-Tu GTPase activity.

Department of Gene Expression, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 37 Prague 6, Czech Republic.

Biochimica et biophysica acta 2005 Aug 31

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The effect of noncatalytic domains 2+3 on the intrinsic activity and thermostability of the EF-Tu GTPase center was evaluated in experiments with isolated domains 1 and six chimeric variants of mesophilic Escherichia coli (Ec) and thermophilic Bacillus stearothermophilus (Bst) EF-Tus. The isolated catalytic domains 1 of both EF-Tus displayed similar GTPase activities at their optimal temperatures. However, noncatalytic domains 2+3 of the EF-Tus influenced the GTPase activity of domains 1 differently, depending on the domain origin. Ecdomains 2+3 suppressed the GTPase activity of the Ecdomain 1, whereas those of BstEF-Tu stimulated the Bstdomain 1 GTPase. Domain 1 and domains 2+3 of both EF-Tus positively cooperated to heat-stabilize their GTPase centers to attain optimal activity at a temperature close to the optimal growth temperature of either organism. This can be explained by a stabilization effect of domains 2+3 on alpha-helical regions of the G-domain as revealed by CD spectroscopy.

Citation

Hana Sanderová, Jirí Jonák. Opposite roles of domains 2+3 of Escherichia coli EF-Tu and Bacillus stearothermophilus EF-Tu in the regulation of EF-Tu GTPase activity. Biochimica et biophysica acta. 2005 Aug 31;1752(1):11-7