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Novel inositol catabolic pathway in T hermotoga maritima
Author(s) -
Rodionova Irina A.,
Leyn Semen A.,
Burkart Michael D.,
Boucher Nathalie,
Noll Kenneth M.,
Osterman Andrei L.,
Rodionov Dmitry A.
Publication year - 2013
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12096
Subject(s) - biology , inositol , catabolism , microbiology and biotechnology , computational biology , biochemistry , metabolism , receptor
Summary myo ‐ inositol ( MI ) is a key sugar alcohol component of various metabolites, e.g. phosphatidylinositol‐based phospholipids that are abundant in animal and plant cells. The seven‐step pathway of MI degradation was previously characterized in various soil bacteria including B acillus subtilis . Through a combination of bioinformatics and experimental techniques we identified a novel variant of the MI catabolic pathway in the marine hyperthermophilic bacterium T hermotoga maritima . By using in vitro biochemical assays with purified recombinant proteins we characterized four inositol catabolic enzymes encoded in the TM 0412– TM 0416 chromosomal gene cluster. The novel catabolic pathway in T . maritima starts as the conventional route using the myo ‐inositol dehydrogenase IolG followed by three novel reactions. The first 2‐keto‐ myo ‐inositol intermediate is oxidized by another, previously unknown NAD ‐dependent dehydrogenase TM 0412 (named IolM ), and a yet unidentified product of this reaction is further hydrolysed by TM 0413 ( IolN ) to form 5‐keto‐ l ‐gluconate. The fourth step involves epimerization of 5‐keto‐ l ‐gluconate to d ‐tagaturonate by TM 0416 ( IolO ). T. maritima is unable to grow on myo ‐inositol as a single carbon source. The determined in vitro specificity of the InoEFGK ( TM 0418– TM 0421) transporter to myo ‐inositol‐phosphate suggests that the novel pathway in T hermotoga utilizes a phosphorylated derivative of inositol.