Header menu link for other important links
X
Role of an N-terminal extension in stability and catalytic activity of a hyperthermostable α/β hydrolase fold esterase
Singh, M.K., Shivakumaraswamy, S., ,
Published in Oxford University Press
2016
PMID: 28967962
Volume: 30
   
Issue: 8
Pages: 559 - 570
Abstract
The carbohydrate esterase family 7 (CE7) enzymes catalyze the deacetylation of acetyl esters of a broad range of alcohols and is unique in its activity towards cephalosporin C. The CE7 fold contains a conserved N-terminal extension that distinguishes it from the canonical α/β hydrolase fold. The hexameric quaternary structure indicates that the N-terminus may affect activity and specificity by controlling access of substrates to the buried active sites via an entrance tunnel. In this context, we characterized the catalytic parameters, conformation and thermal stability of two truncation variants lacking four and ten residues of the N-terminal region of the hyperthermostable Thermotoga maritima CE7 acetyl esterase (TmAcE). The truncations did not affect the secondary structure or the fold but modulated the oligomerization dynamics. A modest increase was observed in substrate specificity for acetylated xylose compared with acetylated glucose. A drastic reduction of ∼30-40°C in the optimum temperature for activity of the variants indicated lower thermal stability. The loss of hyperthermostability appears to be an indirect effect associated with an increase in the conformational flexibility of an otherwise rigid neighboring loop containing a catalytic triad residue. The results suggest that the N-terminal extension was evolutionarily selected to preserve the stability of the enzyme. © 2017 The Author.
About the journal
JournalData powered by TypesetProtein Engineering, Design and Selection
PublisherData powered by TypesetOxford University Press
ISSN17410126
Open AccessNo
Concepts (60)
  •  related image
    ACETYLATION
  •  related image
    Antibiotics
  •  related image
    Carbohydrates
  •  related image
    Enzymes
  •  related image
    Esters
  •  related image
    Hydrolases
  •  related image
    Stability
  •  related image
    Substrates
  •  related image
    Thermodynamic stability
  •  related image
    CARBOHYDRATE ESTERASE
  •  related image
    Conformational flexibility
  •  related image
    Deacetylase
  •  related image
    HYPERTHERMOSTABILITY
  •  related image
    N-TERMINAL EXTENSION
  •  related image
    Quaternary structure
  •  related image
    Secondary structures
  •  related image
    Substrate specificity
  •  related image
    Catalyst activity
  •  related image
    ESTERASE
  •  related image
    Glucose
  •  related image
    Hydrolase
  •  related image
    Xylose
  •  related image
    Bacterial protein
  •  related image
    CARBOXYLESTERASE
  •  related image
    Hybrid protein
  •  related image
    Amino terminal sequence
  •  related image
    Article
  •  related image
    Catalysis
  •  related image
    Controlled study
  •  related image
    Enzyme specificity
  •  related image
    Enzyme stability
  •  related image
    Evolutionary adaptation
  •  related image
    Nonhuman
  •  related image
    Oligomerization
  •  related image
    Priority journal
  •  related image
    Protein conformation
  •  related image
    Protein secondary structure
  •  related image
    Temperature
  •  related image
    Thermostability
  •  related image
    THERMOTOGA MARITIMA
  •  related image
    Bacterium
  •  related image
    Chemistry
  •  related image
    Enzymology
  •  related image
    Escherichia coli
  •  related image
    Genetics
  •  related image
    Heat
  •  related image
    Metabolism
  •  related image
    Molecular model
  •  related image
    pH
  •  related image
    PLIABILITY
  •  related image
    PROTEIN UNFOLDING
  •  related image
    Bacteria
  •  related image
    Bacterial proteins
  •  related image
    CARBOXYLIC ESTER HYDROLASES
  •  related image
    Hot temperature
  •  related image
    Hydrogen-ion concentration
  •  related image
    Models, molecular
  •  related image
    PLIABILITY
  •  related image
    PROTEIN UNFOLDING
  •  related image
    Recombinant fusion proteins