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.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-016-0318-5) contains supplementary material, which is available to authorized users.

Estructura y función de las oxigenasas tipo Rieske/mononuclear

“…Las oxigenasas Rieske/mononuclear están ampliamente distribuidas en bacterias (proteobacterias, actinobacterias, algunas cianobacterias y firmicutes) e incluso en algunas arqueas (Chakraborty et al, 2012) se ha descrito que estas enzimas están presentes también en bacterias termófilas, sin embargo, hasta el momento no se ha reportado la función de alguna de ellas (Chakraborty, Suzuki-Minakuchi, Okada & Nojiri, 2017). La mayoría de las oxigenasas Rieske/mononuclear presentes en bacterias participan en rutas de degradación de compuestos aromáticos policíclicos, como el naftaleno (Ensley, Gibson, & Laborde, 1982;, carbazol (Sato et al, 1997), bifenil (Haddock & Gibson, 1995), benzoato (Wolfe et al, 2002), cumeno (Dong et al, 2005), oxoquinolina (Rosche, Tshisuaka, Fetzner & Lingens, 1995), ftalato (Batie, Lahaie & Ballous, 1987), benzeno (Mason, Butler, Cammack & Shergill, 1997), tolueno (Jiang, Parales, & Gibson, 1999), entre otros.…”

Contrasting Mechanisms of Aromatic and Aryl-Methyl Substituent Hydroxylation by the Rieske Monooxygenase Salicylate 5-Hydroxylase

“…Rieske oxygenases (ROs) are nonheme iron-containing enzymes that catalyze a remarkably expansive range of reactions and act upon a diverse group of substrate chemical types. − Found widely across nature, − the ROs are increasingly appreciated for their roles and applications in human health, ,− environmental biotechnology, − agriculture, and chemoenzymatic synthesis. − Collectively, the catalytic repertoire of the RO family exceeds even those of other well-studied oxygenases, including cytochrome P450, dinuclear iron-containing hydrocarbon monooxygenases, flavin oxygenases, and α-ketoacid-linked monooxygenases. ,− …”

A Novel Gene Cluster Is Involved in the Degradation of Lignin-Derived Monoaromatics in Thermus oshimai JL-2

“…Exploring the unculturable microbial population in search of novel thermozymes and mining the large pool of genomic data already present in public databases might lead to the discovery of enzymes with desired properties. Following the latter strategy, we previously identified several Rieske nonheme iron oxygenase (RO) (34,35) homologs in thermophilic bacteria, which indicates the possibility of transforming a wide array of aromatic hydrocarbons (36). One such organism was Thermus oshimai JL-2, an aerobic thermophile isolated as a nitrate reducer from U.S. Great Basin hot springs (37,38).…”