Protein Engineering vol. 16 no. 7 pp. 463-465, 2003
© 2003 Oxford University Press
A long insertion reverts the functional effect of a substitution in acetylcholinesterase
Institute for Technical Biochemistry, Allmandring 31, University of Stuttgart, 70569 Stuttgart, Germany
1 To whom correspondence should be addressed. e-mail: itbfvi{at}po.uni-stuttgart.de
Proteins are thought to undertake single substitutions, deletions and insertions to explore the fitness landscape. Nevertheless, the ways in which these different kind of mutations act together to alter a protein phenotype remain poorly described. We introduced incrementally the single substitution W290A and a 26 amino acid long insertion at the 297 location in the Nippostrongylus brasiliensis acetylcholinesterase B sequence and analysed in vitro the induced changes in the hydrolysis rate of three hemi-substrates: pirimicarb, paraoxon methyl and omethoate. The substitution decreased the hydrolysis rate of the three hemi-substrates. The insertion did not influence this kinetic alteration induced by the substitution for the former hemi-substrate, but reverted it for the two others. These results show that two different kinds of mutations can interact together to influence the direction of a protein’s adaptative walk on the fitness landscape.
Received January 28, 2003; revised April 25, 2003; accepted June 6, 2003.