Kinetic and sequence-structure-function analysis of known LinA variants with different hexachlorocyclohexane isomers.

ABSTRACT: BACKGROUND: Here we report specific activities of all seven naturally occurring LinA variants towards three different isomers, ?, ? and ?, of a priority persistent pollutant, hexachlorocyclohexane (HCH). Sequence-structure-function differences contributing to the differences in their stereospecificity for ?-, ?-, and ?-HCH and enantiospecificity for (+)- and (-)-? -HCH are also discussed. METHODOLOGY/PRINCIPAL FINDINGS: Enzyme kinetic studies were performed with purified LinA variants. Models of LinA2(B90A) A110T, A111C, A110T/A111C and LinA1(B90A) were constructed using the FoldX computer algorithm. Turnover rates (min(-1)) showed that the LinAs exhibited differential substrate affinity amongst the four HCH isomers tested. ?-HCH was found to be the most preferred substrate by all LinA's, followed by the ? and then ? isomer. CONCLUSIONS/SIGNIFICANCE: The kinetic observations suggest that LinA-?1-7 is the best variant for developing an enzyme-based bioremediation technology for HCH. The majority of the sequence variation in the various linA genes that have been isolated is not neutral, but alters the enantio- and stereoselectivity of the encoded proteins.

SUBMITTER: Sharma P 

PROVIDER: S-EPMC3174995 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature