Diversity of Alkane Hydroxylase Systems in the Environment

Abstract

Résumé -Diversité des systèmes alcane hydroxylase dans l'environnement -La première étape dans la dégradation aérobie des alcanes par les bactéries, les levures et les champignons est catalysée par des oxygénases, une classe d'enzymes capables d'introduire des atomes d'oxygène issus de l'oxygène moléculaire dans le substrat alcane. Ces enzymes jouent un rôle important dans la biodégradation du pétrole et dans la biodégradation cométabolique de composés tels que le trichloroéthylène et les éthers-carburants. De plus, ce sont des biocatalyseurs très utiles qui peuvent également servir de modèles pour caractériser une réaction chimique difficile : l'activation régio-et stéréospécifique de la liaison C-H. Plusieurs autres classes d'enzymes catalysent l'oxydation des alcanes. Les souches de levures capables de dégrader les alcanes contiennent plusieurs alcanes hydroxylases appartenant à la superfamille des P450, alors que différentes bactéries contiennent des enzymes similaires au système alcane hydroxylase membranaire de Pseudomonas putida GPo1. Les alcanes à courte chaîne sont probablement oxydés par des alcanes hydroxylases solubles similaires aux méthanes monooxygénases. La présence dans l'environnement de ces oxygénases a été étudiée dans des échantillons de sols et aquifères uniquement pour les alcanes hydroxylases associés aux membranes. Abstract -Diversity of Alkane Hydroxylase Systems in the Environment

Alcanivorax pacificus sp. nov., isolated from a deep-sea pyrene-degrading consortium

“…Based on amino acid sequences deduced from the alkB gene, strain W11-5 T clustered with A. dieselolei B-5 T , A. balearicus MACL04 T and A. venustensis ISO4 T ( Supplementary Fig. S3), forming a separate group with similarities of 78.7-82.5 %; however, compared to phylogenetic positions based on 16S rRNA gene sequences, there was no clear grouping of species, as previously described by Van Beilen et al (2003). For example, A. dieselolei B-5 T and A. borkumensis SK2 T contain multiple alkB gene sequences, therefore, phylogenetic analysis of their deduced amino acid sequences placed them on completely different branches, unlike analyses based on 16S rRNA and gyrB gene sequences ( Supplementary Fig.…”

The Cytochrome P450 Enzyme CYP96A15 Is the Midchain Alkane Hydroxylase Responsible for Formation of Secondary Alcohols and Ketones in Stem Cuticular Wax of Arabidopsis

“…This distinguishes it from most other known P450 enzymes, alkane hydroxylases, and fatty acid hydroxylases, which can only catalyze reactions on terminal or subterminal carbons of the substrates (e.g. v-1 or v-2; Whyte et al, 1998;van Beilen et al, 2003;Kandel et al, 2005Kandel et al, , 2006. To date, only one other P450 enzyme with in-chain hydroxylase activity has been described and it prefers C12 fatty acid substrates very different from the VLC alkane substrates of MAH1 (Morant et al, 2007).…”

“…To our knowledge, this is the first alkane hydroxylase reported from plants. Only few such enzymes had previously been described in bacteria and yeast (Saccharomyces cerevisiae; van Beilen et al, 2003;van Beilen and Funhoff, 2007) and only a few of these are able to metabolize medium-to long-chain alkane (#C 16 ) substrates. Furthermore, among the few long-chain alkane hydroxylases that have been successfully cloned and characterized, none are reported to be cytochrome P450 enzymes (Tani et al, 2001;van Beilen and Funhoff, 2007).…”

Enzymatic Catalysis of Hydrocarbons Oxidation “in vitro” (Review)

“…These enzymes, which introduce oxygen atoms derived from molecular oxygen into the alkane substrate, play an important role in oil bioremediation and in the cometabolic degradation of compounds such as trichloroethylene and fuel oxygenates [10]. In addition, they are useful biocatalysts and important models for a difficult chemical reaction -regio-and stereospecific activation of C-H bonds.…”

“…Short-chain alkanes are probably oxidized by alkane hydroxylases related to the soluble and particulate methane monooxygenases. Only the membrane-bound enzymes have been studied with respect to their prevalence in environments such as soils or aquifers [10].…”