Multiple nucleophilic elbows leading to multiple active sites in a single module esterase from Sorangium cellulosum
Journal article, 2015

The catalytic residues in carbohydrate esterase enzyme families constitute a highly conserved triad: serine, histidine and aspartic acid. This catalytic triad is generally located in a very sharp turn of the protein backbone structure, called the nucleophilic elbow and identified by the consensus sequence GXSXG. An esterase from Sorangium cellulosum Soce56 that contains five nucleophilic elbows was cloned and expressed in Escherichia coli and the function of each nucleophilic elbowed site was characterized. In order to elucidate the function of each nucleophilic elbow, site directed mutagenesis was used to generate variants with deactivated nucleophilic elbows and the functional promiscuity was analyzed. In silica analysis together with enzymological characterization interestingly showed that each nucleophilic elbow formed a local active site with varied substrate specificities and affinities. To our knowledge, this is the first report presenting the role of multiple nucleophilic elbows in the catalytic promiscuity of an esterase. Further structural analysis at protein unit level indicates the new evolutionary trajectories in emerging promiscuous esterases.


Active sites

Protein modeling

Nucleophilic elbow


Gupta Udatha

University of Oslo

Karina M. Madsen

Technical University of Denmark (DTU)

G. Panagiotou

The University of Hong Kong

Lisbeth Olsson

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Journal of Structural Biology

1047-8477 (ISSN) 1095-8657 (eISSN)

Vol. 190 3 314-327

Subject Categories

Cell Biology






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