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Coordinated regulation of nitrogen fixation and molybdate transport by molybdenum
Author(s) -
Demtröder Lisa,
Narberhaus Franz,
Masepohl Bernd
Publication year - 2019
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14152
Subject(s) - nitrogenase , diazotroph , nitrogen fixation , molybdate , molybdenum , biology , nitrogen , biochemistry , cofactor , sulfite oxidase , bacteria , botany , sulfite , chemistry , inorganic chemistry , enzyme , genetics , organic chemistry
Summary Biological nitrogen fixation, the reduction of chemically inert dinitrogen to bioavailable ammonia, is a central process in the global nitrogen cycle highly relevant for life on earth. N 2 reduction to NH 3 is catalyzed by nitrogenases exclusively synthesized by diazotrophic prokaryotes. All diazotrophs have a molybdenum nitrogenase containing the unique iron‐molybdenum cofactor FeMoco. In addition, some diazotrophs encode one or two alternative Mo‐free nitrogenases that are less efficient at reducing N 2 than Mo‐nitrogenase. To permit biogenesis of Mo‐nitrogenase and other molybdoenzymes when Mo is scarce, bacteria synthesize the high‐affinity molybdate transporter ModABC. Generally, Mo supports expression of Mo‐nitrogenase genes, while it represses production of Mo‐free nitrogenases and ModABC. Since all three nitrogenases and ModABC can reach very high levels at suitable Mo concentrations, tight Mo‐mediated control saves considerable resources and energy. This review outlines the similarities and differences in Mo‐responsive regulation of nitrogen fixation and molybdate transport in diverse diazotrophs.