1g42
STRUCTURE OF 1,3,4,6-TETRACHLORO-1,4-CYCLOHEXADIENE HYDROLASE (LINB) FROM SPHINGOMONAS PAUCIMOBILIS COMPLEXED WITH 1,2-DICHLOROPROPANE
Structural highlights
FunctionLINB_SPHIU Catalyzes hydrolytic cleavage of carbon-halogen bonds in halogenated aliphatic compounds, leading to the formation of the corresponding primary alcohols, halide ions and protons. Has a broad substrate specificity since not only monochloroalkanes (C3 to C10) but also dichloroalkanes (> C3), bromoalkanes, and chlorinated aliphatic alcohols are good substrates (PubMed:10100638, PubMed:9293022). Shows almost no activity with 1,2-dichloroethane, but very high activity with the brominated analog (PubMed:9293022). Is involved in the degradation of the important environmental pollutant gamma-hexachlorocyclohexane (gamma-HCH or lindane) as it also catalyzes conversion of 1,3,4,6-tetrachloro-1,4-cyclohexadiene (1,4-TCDN) to 2,5-dichloro-2,5-cyclohexadiene-1,4-diol (2,5-DDOL) via the intermediate 2,4,5-trichloro-2,5-cyclohexadiene-1-ol (2,4,5-DNOL) (PubMed:7691794). This degradation pathway allows S.japonicum UT26 to grow on gamma-HCH as the sole source of carbon and energy.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe hydrolysis of haloalkanes to their corresponding alcohols and inorganic halides is catalyzed by alpha/beta-hydrolases called haloalkane dehalogenases. The study of haloalkane dehalogenases is vital for the development of these enzymes if they are to be utilized for bioremediation of organohalide-contaminated industrial waste. We report the kinetic and structural analysis of the haloalkane dehalogenase from Sphingomonas paucimobilis UT26 (LinB) in complex with each of 1,2-dichloroethane and 1,2-dichloropropane and the reaction product of 1-chlorobutane turnover. Activity studies showed very weak but detectable activity of LinB with 1,2-dichloroethane [0.012 nmol s(-1) (mg of enzyme)(-1)] and 1,2-dichloropropane [0.027 nmol s(-1) (mg of enzyme)(-1)]. These activities are much weaker compared, for example, to the activity of LinB with 1-chlorobutane [68.2 nmol s(-1) (mg of enzyme)(-1)]. Inhibition analysis reveals that both 1,2-dichloroethane and 1,2-dichloropropane act as simple competitive inhibitors of the substrate 1-chlorobutane and that 1,2-dichloroethane binds to LinB with lower affinity than 1,2-dichloropropane. Docking calculations on the enzyme in the absence of active site water molecules and halide ions confirm that these compounds could bind productively. However, when these moieties were included in the calculations, they bound in a manner similar to that observed in the crystal structure. These data provide an explanation for the low activity of LinB with small, chlorinated alkanes and show the importance of active site water molecules and reaction products in molecular docking. Exploring the structure and activity of haloalkane dehalogenase from Sphingomonas paucimobilis UT26: evidence for product- and water-mediated inhibition.,Oakley AJ, Prokop Z, Bohac M, Kmunicek J, Jedlicka T, Monincova M, Kuta-Smatanova I, Nagata Y, Damborsky J, Wilce MC Biochemistry. 2002 Apr 16;41(15):4847-55. PMID:11939779[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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