2DC1

Crystal structure of archaeal highly thermostable L-aspartate dehydrogenase/NAD/citrate ternary complex.

(2007) FEBS J 274: 4315-4325

• PubMed: 17651440 Search on PubMed
• DOI: https://doi.org/10.1111/j.1742-4658.2007.05961.x
• Primary Citation of Related Structures:  
  2DC1


• PubMed Abstract: 
  

  The crystal structure of the highly thermostable L-aspartate dehydrogenase (L-aspDH; EC 1.4.1.21) from the hyperthermophilic archaeon Archaeoglobus fulgidus was determined in the presence of NAD and a substrate analog, citrate. The dimeric structure of A. fulgidus L-aspDH was refined at a resolution of 1.9 A with a crystallographic R-factor of 21.7% (R(free) = 22.6%). The structure indicates that each subunit consists of two domains separated by a deep cleft containing an active site. Structural comparison of the A. fulgidus L-aspDH/NAD/citrate ternary complex and the Thermotoga maritima L-aspDH/NAD binary complex showed that A. fulgidus L-aspDH assumes a closed conformation and that a large movement of the two loops takes place during substrate binding. Like T. maritima L-aspDH, the A. fulgidus enzyme is highly thermostable. But whereas a large number of inter- and intrasubunit ion pairs are responsible for the stability of A. fulgidus L-aspDH, a large number of inter- and intrasubunit aromatic pairs stabilize the T. maritima enzyme. Thus stabilization of these two L-aspDHs appears to be achieved in different ways. This is the first detailed description of substrate and coenzyme binding to L-aspDH and of the molecular basis of the high thermostability of a hyperthermophilic L-aspDH.

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Organizational Affiliation: 

Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.