The Structure of a Novel Thermophilic Esterase from the Planctomycetes Species, Thermogutta terrifontis Reveals an Open Active Site Due to a Minimal ‘Cap’ Domain

DOI: 10.3389/fmicb.2015.01294
PMID: 26635762

Authors: Christopher Sayer (University of Exeter) , Zalan Szabo (Microdish BV) , Michail N. Isupov (University of Exeter) , Colin Ingham (Microdish BV) , Jennifer A Littlechild (University of Exeter)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Frontiers In Microbiology , VOL 6

State: Published (Approved)
Published: November 2015
Diamond Proposal Number(s): 8889 , 11945

Abstract: A carboxyl esterase (TtEst2) has been identified in a novel thermophilic bacterium, Thermogutta terrifontis from the phylum Planctomycetes and has been cloned and over-expressed in Escherichia coli. The enzyme has been characterised biochemically and shown to have activity towards small p-nitrophenyl (pNP) carboxylic esters with optimal activity for pNP-acetate.The enzyme shows moderate thermostability retaining 75% activity after incubation for 30 minutes at 70°C. The crystal structures have been determined for the native TtEst2 and its complexes with the carboxylic acid products propionate, butyrate and valerate. TtEst2 differs from most enzymes of the α/β-hydrolase family 3 as it lacks the majority of the ‘cap’ domain and its active site cavity is exposed to the solvent. The bound ligands have allowed the identification of the carboxyl pocket in the enzyme active site. Comparison of TtEst2 with structurally related enzymes has given insight into how differences in their substrate preference can be rationalised based upon the properties of their active site pockets.

Journal Keywords: Planctomycetes; Thermophilic Enzymes; Carboxyl Esterase; X-Ray Structure; Biocatalysis

Subject Areas: Biology and Bio-materials, Chemistry


Instruments: I04-1-Macromolecular Crystallography (fixed wavelength)