Structure Report for: 4H77

Okai, M., Ohtsuka, J., Imai, F.L, Mase, T., Moriuchi, R., Tsuda, M, Nagata, K., Nagata, Y., Tanokura, M.

Title: Crystal Structure and Site-Directed Mutagenesis Analyses of Haloalkane Dehalogenase LinB from Sphingobium sp. Strain MI1205
Okai M, Ohtsuka J, Imai LF, Mase T, Moriuchi R, Tsuda M, Nagata K, Nagata Y, Tanokura M
Ref: Journal of Bacteriology, 195:2642, 2013 : PubMed
Abstract


ESTHER: Okai_2013_J.Bacteriol_195_2642
PubMedSearch: Okai 2013 J.Bacteriol 195 2642
PubMedID: 23564170
Gene_locus related to this paper: sphpi-q6vqx3

Abstract

The enzymes LinBUT and LinBMI (LinB from Sphingobium japonicum UT26 and Sphingobium sp. MI1205, respectively) catalyze the hydrolytic dechlorination of beta-hexachlorocyclohexane (beta-HCH) and yield different products, 2,3,4,5,6-pentachlorocyclohexanol (PCHL) and 2,3,5,6-tetrachlorocyclohexane-1,4-diol (TCDL), respectively, despite their 98% identity in amino acid sequence. To reveal the structural basis of their different enzymatic properties, we performed site-directed mutagenesis and X-ray crystallographic studies of LinBMI and its seven point mutants. The mutation analysis revealed that the seven amino acid residues uniquely found in LinBMI were categorized into three groups based on the efficiency of the first-step (from beta-HCH to PCHL) and second-step (from PCHL to TCDL) conversions. Crystal structure analyses of wild-type LinBMI and its seven point mutants indicated how each mutated residue contributed to the first- and second-step conversions by LinBMI. The dynamics simulation analyses of wild-type LinBMI and LinBUT revealed that the entrance of the substrate access tunnel of LinBUT was more flexible than that of LinBMI, which could lead to the different efficiencies of dehalogenation activity between these dehalogenases.