1D3A: Crystal Structure Of The Wild Type Halophilic Malate Dehydrogenase In The Apo Form

Previous biophysical studies of tetrameric malate dehydrogenase from the halophilic archaeon Haloarcula marismortui (Hm MalDH) have revealed the importance of protein-solvent interactions for its adaptation to molar salt conditions that strongly affect protein solubility, stability, and activity, in general. The structures of the E267R stability mutant of apo (-NADH) Hm MalDH determined to 2.6 A resolution and of apo (-NADH) wild type Hm MalDH determined to 2.9 A resolution, presented here, highlight a variety of novel protein-solvent features involved in halophilic adaptation. The tetramer appears to be stabilized by ordered water molecule networks and intersubunit complex salt bridges "locked" in by bound solvent chloride and sodium ions. The E267R mutation points into a central ordered water cavity, disrupting protein-solvent interactions. The analysis of the crystal structures showed that halophilic adaptation is not aimed uniquely at "protecting" the enzyme from the extreme salt conditions, as may have been expected, but, on the contrary, consists of mechanisms that harness the high ionic concentration in the environment.
PDB ID: 1D3ADownload
MMDB ID: 12970
PDB Deposition Date: 1999/9/28
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.94  Å
Source Organism:
Similar Structures:
Biological Unit for 1D3A: tetrameric; determined by author and by software (PISA,PQS)
Molecular Components in 1D3A
Label Count Molecule
Proteins (4 molecules)
Halophilic Malate Dehydrogenase(Gene symbol: RR_RS16060)
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB