title: Thermophilic bacteria are potential sources of novel Rieske non-heme iron oxygenases.
abstract: Rieske non-heme iron oxygenases, which have a Rieske-type [2Fe-2S] cluster and a non-heme catalytic iron center, are an important family of oxidoreductases involved mainly in regio- and stereoselective transformation of a wide array of aromatic hydrocarbons. Though present in all domains of life, the most widely studied Rieske non-heme iron oxygenases are found in mesophilic bacteria. The present study explores the potential for isolating novel Rieske non-heme iron oxygenases from thermophilic sources. Browsing the entire bacterial genome database led to the identification of 45 homologs from thermophilic bacteria distributed mainly among Chloroflexi, Deinococcus-Thermus and Firmicutes. Thermostability, measured according to the aliphatic index, showed higher values for certain homologs compared with their mesophilic relatives. Prediction of substrate preferences indicated that a wide array of aromatic hydrocarbons could be transformed by most of the identified oxygenase homologs. Further identification of putative genes encoding components of a functional oxygenase system opens up the possibility of reconstituting functional thermophilic Rieske non-heme iron oxygenase systems with novel properties.
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
authors.forename: Joydeep
authors.initials: J
authors.lastname: Chakraborty
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
authors.forename: Chiho
authors.initials: C
authors.lastname: Suzuki-Minakuchi
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Okada
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan. anojiri@mail.ecc.u-tokyo.ac.jp.
authors.forename: Hideaki
authors.identifier: http://orcid.org/0000-0003-3091-8691
authors.initials: H
authors.lastname: Nojiri
keywords: Aromatic hydrocarbons; Biotransformation; Oxidoreductase; Rieske non-heme iron oxygenase; Thermophiles