3S5C

Crystal Structure of a Hexachlorocyclohexane dehydrochlorinase (LinA) Type2

Summary for 3S5C

• Entry DOI: 10.2210/pdb3s5c/pdb
• Descriptor: LinA (1 entity in total)
• Functional Keywords: hexachlorocyclohexane dehydrochlorinase, transferase
• Biological source: uncultured organism
• Total number of polymer chains: 7
• Total formula weight: 121348.27

Authors

Kukshal, V.,Macwan, A.S.,Kumar, A.,Ramachandran, R. (deposition date: 2011-05-23, release date: 2012-05-23, Last modification date: 2023-11-01)

Primary citation

Macwan, A.S.,Kukshal, V.,Srivastava, N.,Javed, S.,Kumar, A.,Ramachandran, R.
Crystal structure of the hexachlorocyclohexane dehydrochlorinase (LinA-type2): mutational analysis, thermostability and enantioselectivity
Plos One, 7:e50373-e50373, 2012

PubMed Abstract: Hexachlorocyclohexane dehydrochlorinase (LinA) mediates dehydrochlorination of γ-HCH to 1, 3, 4, 6-tetrachloro-1,4-cyclohexadiene that constitutes first step of the aerobic degradation pathway. We report the 3.5 Å crystal structure of a thermostable LinA-type2 protein, obtained from a soil metagenome, in the hexagonal space group P6(3)22 with unit cell parameters a = b = 162.5, c = 186.3 Å, respectively. The structure was solved by molecular replacement using the co-ordinates of LinA-type1 that exhibits mesophile-like properties. Structural comparison of LinA-type2 and -type1 proteins suggests that thermostability of LinA-type2 might partly arise due to presence of higher number of ionic interactions, along with 4% increase in the intersubunit buried surface area. Mutational analysis involving the differing residues between the -type1 and -type2 proteins, circular dichroism experiments and functional assays suggest that Q20 and G23 are determinants of stability for LinA-type2. It was earlier reported that LinA-type1 exhibits enantioselectivity for the (-) enantiomer of α-HCH. Contrastingly, we identified that -type2 protein prefers the (+) enantiomer of α-HCH. Structural analysis and molecular docking experiments suggest that changed residues K20Q, L96C and A131G, vicinal to the active site are probably responsible for the altered enantioselectivity of LinA-type2. Overall the study has identified features responsible for the thermostability and enantioselectivity of LinA-type2 that can be exploited for the design of variants for specific biotechnological applications.

PubMed: 23209726
DOI: 10.1371/journal.pone.0050373

Experimental method

X-RAY DIFFRACTION (3.5 Å)