An evolutionary perspective on the first disulfide bond in members of the cholinesterase-carboxylesterase (COesterase) family: Possible outcomes for cholinesterase expression in prokaryotes

Publication date: Available online 14 May 2019Source: Chemico-Biological InteractionsAuthor(s): Arnaud Chatonnet, Xavier Brazzolotto, Thierry Hotelier, Nicolas Lenfant, Pascale Marchot, Yves BourneAbstractWithin the alpha/beta hydrolase fold superfamily of proteins, the COesterase group (carboxylesterase type B, block C, cholinesterases…) diverged from the other groups through simultaneous integration of an N-terminal, first disulfide bond and a significant increase in the protein mean size. This first disulfide bond ties a large Cys loop, which in the cholinesterases is named the omega loop and forms the upper part of the active center gorge, essential for the high catalytic activity of these enzymes. In some non-catalytic members of the family, the loop may be necessary for heterologous partner recognition. Reshuffling of this protein portion occurred at the time of emergence of the fungi/metazoan lineage. Homologous proteins with this first disulfide bond are absent in plants but they are found in a limited number of bacterial genomes. In prokaryotes, the genes coding for such homologous proteins may have been acquired by horizontal transfer. However, the cysteines of the first disulfide bond are often lost in bacteria. Natural expression in bacteria of CO-esterases comprising this disulfide bond may have required compensatory mutations or expression of new chaperones. This disulfide bond may also challenge expression of the eukaryote-specific cholinesterases in prokaryo...
Source: Chemico Biological Interactions - Category: Biochemistry Source Type: research