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PDBsum entry 3s5c
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PDB id:
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Transferase
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Title:
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Crystal structure of a hexachlorocyclohexane dehydrochlorinase (lina) type2
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Structure:
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Lina. Chain: b, a, c, d, e, f, g. Synonym: hexachlorocyclohexane dehydrochlorinase. Engineered: yes
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Source:
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Uncultured organism. Organism_taxid: 155900. Expressed in: escherichia coli. Expression_system_taxid: 562.
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Resolution:
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3.50Å
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R-factor:
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0.183
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R-free:
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0.271
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Authors:
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V.Kukshal,A.S.Macwan,A.Kumar,R.Ramachandran
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Key ref:
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A.S.Macwan
et al.
(2012).
Crystal structure of the hexachlorocyclohexane dehydrochlorinase (LinA-type2): mutational analysis, thermostability and enantioselectivity.
Plos One,
7,
e50373.
PubMed id:
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Date:
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23-May-11
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Release date:
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23-May-12
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PROCHECK
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Headers
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References
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B5ANU3
(B5ANU3_9ZZZZ) -
LinA from uncultured organism
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Seq:
Struc:
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156 a.a.
148 a.a.
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Key: |
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PfamA domain |
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Secondary structure |
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CATH domain |
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Plos One
7:e50373
(2012)
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PubMed id:
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Crystal structure of the hexachlorocyclohexane dehydrochlorinase (LinA-type2): mutational analysis, thermostability and enantioselectivity.
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A.S.Macwan,
V.Kukshal,
N.Srivastava,
S.Javed,
A.Kumar,
R.Ramachandran.
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ABSTRACT
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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.
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