5ELM

Structural basis for an atypical active site of an l-aspartate/glutamate-specific racemase from Escherichia coli

(2015) FEBS Lett 589: 3842-3847

• PubMed: 26555188 Search on PubMed
• DOI: https://doi.org/10.1016/j.febslet.2015.11.003
• Primary Citation of Related Structures:  
  5ELL, 5ELM


• PubMed Abstract: 
  

  We determined the crystal structure of EcL-DER to elucidate protein function and substrate specificity. Unlike other asp/glu racemases, EcL-DER has an unbalanced pair of catalytic residues, Thr83/Cys197, at the active site that is crucial for L- to D-unidirectional racemase activity. EcL-DER exhibited racemase activity for both L-glutamate and L-aspartate, but had threefold higher activity for L-glutamate. Based on the structure of the EcL-DER(C197S) mutant in complex with L-glutamate, we determined the binding mode of the L-glutamate substrate in EcL-DER and provide a structural basis for how the protein utilizes L-glutamate as a main substrate. The unidirectionality, despite an equilibrium constant of unity, can be understood in terms of the Haldane relationship.

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Organizational Affiliation: 

School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea.