Open AccessUnidirectional mannitol synthesis ofAcinetobacter baumanniiMtlD is facilitated by the helix–loop–helix-mediated dimer formation
Author(s) -
Heng-Keat Tam,
Patricia König,
Stephanie Himpich,
Ngoc Dinh Ngu,
Rupert Abele,
Volker Müller,
Klaas M. Pos
Publication year - 2022
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.2107994119
Subject(s) - chemistry , phosphatase , dehydrogenase , biochemistry , mannitol , helix (gastropod) , stereochemistry , enzyme , biology , ecology , snail
Significance Mannitol biosynthesis is essential forAcinetobacter baumannii to cope with osmotic stress. Currently, onlyPseudomonas putida ,Acinetobacter baylyi , andA. baumannii are able to de novo synthesize mannitol by a structurally unique bifunctional mannitol-1-phosphate dehydrogenase/phosphatase (AbMtlD). The molecular mechanism of reduction and dephosphorylation of fructose-6-phosphate to mannitol is highly dependent on the substrate shuffling from one protomer to the other protomer by a unique helix–loop–helix domain–mediated dimer formation, thus ensuring unidirectional and efficient biosynthesis of mannitol. These observations support an evolutionary adaptation of AbMtlD by fusion of dehydrogenase and phosphatase domains to facilitate efficient unidirectional enzymatic production of mannitol, unifying regulatory control and minimizing the intracellular concentration of toxic mannitol-1-phosphate during salt stress.