Experimental Data Snapshot

  • Resolution: 1.45 Å
  • R-Value Free: 0.180 
  • R-Value Work: 0.155 
  • R-Value Observed: 0.156 

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Lowering pH optimum of activity of SshEstI, a slightly alkaliphilic archaeal esterase of the hormone-sensitive lipase family.

Ohara, K.Oshima, Y.Unno, H.Nagano, S.Kusunoki, M.Takahashi, S.Waki, T.Yamashita, S.Nakayama, T.

(2024) J Biosci Bioeng 

  • DOI: https://doi.org/10.1016/j.jbiosc.2024.05.010
  • Primary Citation of Related Structures:  
    8YFY, 8YFZ

  • PubMed Abstract: 

    SshEstI, a carboxylesterase from the thermoacidophilic archaeon Saccharolobus shibatae, is a member of the hormone-sensitive lipase family that displays slightly alkaliphilic activity with an optimum activity at pH 8.0. In this study, three distinct strategies were explored to confer acidophilic properties to SshEstI. The first strategy involved engineering the oxyanion hole by replacing Gly81 with serine or aspartic acid. The G81S mutant showed optimum activity at pH 7.0, whereas the aspartic acid mutant (G81D) rendered the enzyme slightly acidophilic with optimum activity observed at pH 6.0; however, k cat and k cat /K m values were reduced by these substitutions. The second strategy involved examining the effects of surfactant additives on the pH-activity profiles of SshEstI. The results showed that cetyltrimethylammonium bromide (CTAB) enhanced wild-type enzyme (WT) activity at acidic pH values. In the presence of 0.1 mM CTAB, G81S and G81D were acidophilic enzymes with optimum activity at pH 6.0 and 4.0, respectively, although their enzyme activities were low. The third strategy involved engineering the active site to resemble that of kumamolisin-As (kuma-As), an acidophilic peptidase of the sedolisin family. The catalytic triad of kuma-As was exchanged into SshEstI using site-directed mutagenesis. X-ray crystallographic analysis of the mutants (H274D and H274E) revealed that the potential hydrogen donor-acceptor distances around the active site of WT were fully maintained in these mutants. However, these mutants were inactive at pH 4-8.

  • Organizational Affiliation

    Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8579, Japan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Carboxylesterase305Saccharolobus shibataeMutation(s): 1 
Gene Names: SshEstIJ5U21_01394J5U22_01308
Find proteins for Q5NU42 (Saccharolobus shibatae)
Explore Q5NU42 
Go to UniProtKB:  Q5NU42
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ5NU42
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
BOG (Subject of Investigation/LOI)
Query on BOG

Download Ideal Coordinates CCD File 
B [auth A]octyl beta-D-glucopyranoside
C14 H28 O6
Experimental Data & Validation

Experimental Data

  • Resolution: 1.45 Å
  • R-Value Free: 0.180 
  • R-Value Work: 0.155 
  • R-Value Observed: 0.156 
  • Space Group: I 2 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.096α = 90
b = 71.817β = 90
c = 137.017γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Japan Society for the Promotion of Science (JSPS)Japan--

Revision History  (Full details and data files)

  • Version 1.0: 2024-07-10
    Type: Initial release