Mutations in salt-bridging residues at the interface of the core and lid domains of epoxide hydrolase StEH1 affect regioselectivity, protein stability and hysteresis
2010 (English)In: Archives of Biochemistry and Biophysics, ISSN 0003-9861, E-ISSN 1096-0384, Vol. 495, no 2, 165-173 p.Article in journal (Refereed) Published
Epoxide hydrolase, StEH1, shows hysteretic behavior in the catalyzed hydrolysis of trans-2-methylstyrene oxide (2-MeSO)(1). Linkage between protein structure dynamics and catalytic function was probed in mutant enzymes in which surface-located salt-bridging residues were substituted. Salt-bridges at the interface of the alpha/beta-hydrolase fold core and lid domains, as well as between residues in the lid domain, between Lys(179)Asp(202), Glu(215)-Arg(41) and Arg(236)-Glu(136) were disrupted by mutations, K179Q E215Q, R236Q and R236Q. All mutants displayed enzyme activity with styrene oxide (SO) and 2-MeSO when assayed at 30 degrees C. Disruption of salt-bridges altered the rates for isomerization between distinct Michaelis complexes, with (1R,2R)-2-MeSO as substrate, presumably as a result of increased dynamics of involved protein segments. Another indication of increased flexibility was a lowered thermostability in all mutants. We propose that the alterations to regioselectivity in these mutants derive from an increased mobility in protein segments otherwise stabilized by salt bridging interactions.
Place, publisher, year, edition, pages
Amsterdam: Elsevier , 2010. Vol. 495, no 2, 165-173 p.
Natural Sciences Biochemistry and Molecular Biology
Research subject Biochemistry
IdentifiersURN: urn:nbn:se:uu:diva-112278DOI: 10.1016/j.abb.2010.01.007ISI: 000275299800009PubMedID: 20079707OAI: oai:DiVA.org:uu-112278DiVA: diva2:285640