Molybdenum plays an essential role in many vital biochemical processes, for which organisms have developed a complete Mo metabolism including uptake/transport, gene regulation, homeostasis and storage. Mo is used within complex cofactors (molybdopterin in diverse oxygen-transferring redox enzymes and an FeMo cofactor in nitrogenases) or simply as single molybdate ions bound to proteins. Recent studies on a Mo storage protein (MoSto) of the N2 fixing bacterium Azotobacter vinelandii revealed that Nature also uses Mo in the form of polyoxometalate clusters. Inorganic polyoxometalate chemistry is a long-standing research field. Polyoxometalate clusters are characterised by their huge variety culminating in “giant clusters” of up to 368 Mo atoms. The MoSto protein in A. vinelandii is related to the Mo-dependent nitrogenase: it supplies the nitrogenase cofactor with Mo to ensure nitrogenase functionality under molybdenum-deficient conditions. Storage as polyoxomolybdate allows the organism to compactly deposit more than 100 Mo ions in a single MoSto molecule. Molybdate uptake is an ATP hydrolysis driven process; molybdate release is ATP-independent but pH-regulated, occurring stepwise above pH 6.8. X-ray structure analysis of the MoSto protein at 1.6 Å resolution revealed a cage-like (αβ)3 protein complex with a central cavity approximately 7250 Å3 in volume. X-ray experiments allowed to detect about 100 Mo atoms iwithin the cavity, 70 of them in defined polynuclear Mo-O aggregates. Here you can see a zoomed view of the central Mo-containing central cavity of the MoSto protein from Azotobacter vinelandii (PDB code: 7ZR4)
#molecularart ... #immolecular ... #nitrogen ... #fixation ... #azotobacter ... #molybdenum ... #xray
Structure rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #nitrogen ... #fixation ... #azotobacter ... #molybdenum ... #xray
Structure rendered with @proteinimaging and depicted with @corelphotopaint
