Mannitol-1-phosphate dehydrogenases/phosphatases: a family of novel bifunctional enzymes for bacterial adaptation to osmotic stress.

Autor: Sand M; Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany., Rodrigues M, González JM, de Crécy-Lagard V, Santos H, Müller V, Averhoff B
Jazyk: angličtina
Zdroj: Environmental microbiology [Environ Microbiol] 2015 Mar; Vol. 17 (3), pp. 711-9. Date of Electronic Publication: 2014 Jun 04.
DOI: 10.1111/1462-2920.12503
Abstrakt: The nutritionally versatile soil bacterium Acinetobacter baylyi ADP1 copes with salt stress by the accumulation of compatible solutes, a strategy that is widespread in nature. This bacterium synthesizes the sugar alcohol mannitol de novo in response to osmotic stress. In a previous study, we identified MtlD, a mannitol-1-phosphate dehydrogenase, which is essential for mannitol biosynthesis and which catalyses the first step in mannitol biosynthesis, the reduction of fructose-6-phosphate (F-6-P) to the intermediate mannitol-1-phosphate (Mtl-1-P). Until now, the identity of the second enzyme, the phosphatase that catalyses the dephosphorylation of Mtl-1-P to mannitol, was elusive. Here we show that MtlD has a unique sequence among known mannitol-1-phosphate dehydrogenases with a haloacid dehalogenase (HAD)-like phosphatase domain at the N-terminus. This domain is indeed shown to have a phosphatase activity. Phosphatase activity is strictly Mg(2+) dependent. Nuclear magnetic resonance analysis revealed that purified MtlD catalyses not only reduction of F-6-P but also dephosphorylation of Mtl-1-P. MtlD of A. baylyi is the first bifunctional enzyme of mannitol biosynthesis that combines Mtl-1-P dehydrogenase and phosphatase activities in a single polypeptide chain. Bioinformatic analysis revealed that the bifunctional enzyme is widespread among Acinetobacter strains but only rarely present in other phylogenetic tribes.
(© 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.)
Databáze: MEDLINE
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