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Title 

Structure of the thermophilic L-Arabinose isomerase from Geobacillus kaustophilus reveals metal-mediated intersubunit interactions for activity and thermostability

Authors 

J M ChoiY J LeeT P CaoS M ShinM K ParkH S LeeE di LuccioS B KimS J LeeSang Jun LeeS H LeeD W Lee

Publisher 

Elsevier

Issue Date 

2016

Citation 

Archives of Biochemistry and Biophysics, vol. 596, no. 0, pp. 51-62

Keywords 

Crystal structureIntersubunit interactionl-arabinose isomeraseSubstrate specificityThermostability

Abstract 

Thermophilic l-arabinose isomerase (AI), which catalyzes the interconversion of l-arabinose and l-ribulose, can be used to produce d-tagatose, a sugar substitute, from d-galactose. Unlike mesophilic AIs, thermophilic AIs are highly dependent on divalent metal ions for their catalytic activity and thermostability at elevated temperatures. However, the molecular basis underlying the substrate preferences and metal requirements of multimeric AIs remains unclear. Here we report the first crystal structure of the apo and holo forms of thermophilic Geobacillus kaustophilus AI (GKAI) in hexamer form. The structures, including those of GKAI in complex with l-arabitol, and biochemical analyses revealed not only how the substrate-binding site of GKAI is formed through displacement of residues at the intersubunit interface when it is bound to Mn2+, but also revealed the water-mediated H-bonding networks that contribute to the structural integrity of GKAI during catalysis. These observations suggest metal-mediated isomerization reactions brought about by intersubunit interactions at elevated temperatures are responsible for the distinct active site features that promote the substrate specificity and thermostability of thermophilic AIs.

ISSN 

0096-9621

Link 

http://dx.doi.org/10.1016/j.abb.2016.02.033

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2019-05-02


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