4CNX: Surface Residue Engineering Of Bovine Carbonic Anhydrase To An Extreme Halophilic Enzyme For Potential Application In Postcombustion Co2 Capture

Enzymes expressed by highly salt-tolerant organisms show many modifications compared with salt-affected counterparts including biased amino acid and lower alpha-helix content, lower solvent accessibility and negative surface charge. Here, we show that halotolerance can be generated in an enzyme solely by modifying surface residues. Rational design of carbonic anhydrase II is undertaken in three stages replacing 18 residues in total, crystal structures confirm changes are confined to surface residues. Catalytic activities and thermal unfolding temperatures of the designed enzymes increase at high salt concentrations demonstrating their shift to halotolerance, whereas the opposite response is found in the wild-type enzyme. Molecular dynamics calculations reveal a key role for sodium ions in increasing halotolerant enzyme stability largely through interactions with the highly ordered first Na(+) hydration shell. For the first time, an approach to generate extreme halotolerance, a trait with broad application in industrial biocatalysis, in a wild-type enzyme is demonstrated.
PDB ID: 4CNXDownload
MMDB ID: 126606
PDB Deposition Date: 2014/1/25
Updated in MMDB: 2015/02
Experimental Method:
x-ray diffraction
Resolution: 1.23  Å
Source Organism:
Similar Structures:
Biological Unit for 4CNX: monomeric; determined by author and by software (PISA)
Molecular Components in 4CNX
Label Count Molecule
Protein (1 molecule)
Carbonic Anhydrase 2(Gene symbol: CA2)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB