Download MendeleyStructural basis for an atypical active site of an l-aspartate/glutamate-specific racemase from Escherichia coli
Ahn, J.W., Chang, J.H., Kim, K.J.(2015) FEBS Lett 589: 3842-3847
- PubMed: 26555188
- 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.
Organizational Affiliation:
School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea.
