4F6T

The crystal structure of the molybdenum storage protein (MoSto) from Azotobacter vinelandii loaded with various polyoxometalates

Summary for 4F6T

• Entry DOI: 10.2210/pdb4f6t/pdb
• Related: 2OGX
• Descriptor: Molybdenum storage protein subunit beta, Molybdenum storage protein subunit alpha, ADENOSINE-5'-TRIPHOSPHATE, ... (9 entities in total)
• Functional Keywords: molybdenum storage, atp hydrolyzation, hexamer, polyoxometalate, pom, rossmanfold like, atp hydrolysis, molybdate, metal binding protein
• Biological source: Azotobacter vinelandii; More
• Cellular location: Cytoplasm: P84253 P84308
• Total number of polymer chains: 2
• Total formula weight: 58788.82

Authors

Kowalewski, B.,Poppe, J.,Schneider, K.,Demmer, U.,Warkentin, E.,Ermler, U. (deposition date: 2012-05-15, release date: 2012-07-18, Last modification date: 2023-09-13)

Primary citation

Kowalewski, B.,Poppe, J.,Demmer, U.,Warkentin, E.,Dierks, T.,Ermler, U.,Schneider, K.
Nature's Polyoxometalate Chemistry: X-ray Structure of the Mo Storage Protein Loaded with Discrete Polynuclear Mo-O Clusters.
J.Am.Chem.Soc., 134:9768-9774, 2012

PubMed Abstract: Some N(2)-fixing bacteria prolong the functionality of nitrogenase in molybdenum starvation by a special Mo storage protein (MoSto) that can store more than 100 Mo atoms. The presented 1.6 Å X-ray structure of MoSto from Azotobacter vinelandii reveals various discrete polyoxomolybdate clusters, three covalently and three noncovalently bound Mo(8), three Mo(5-7), and one Mo(3) clusters, and several low occupied, so far undefinable clusters, which are embedded in specific pockets inside a locked cage-shaped (αβ)(3) protein complex. The structurally identical Mo(8) clusters (three layers of two, four, and two MoO(n) octahedra) are distinguishable from the [Mo(8)O(26)](4-) cluster formed in acidic solutions by two displaced MoO(n) octahedra implicating three kinetically labile terminal ligands. Stabilization in the covalent Mo(8) cluster is achieved by Mo bonding to Hisα156-N(ε2) and Gluα129-O(ε1). The absence of covalent protein interactions in the noncovalent Mo(8) cluster is compensated by a more extended hydrogen-bond network involving three pronounced histidines. One displaced MoO(n) octahedron might serve as nucleation site for an inhomogeneous Mo(5-7) cluster largely surrounded by bulk solvent. In the Mo(3) cluster located on the 3-fold axis, the three accurately positioned His140-N(ε2) atoms of the α subunits coordinate to the Mo atoms. The formed polyoxomolybdate clusters of MoSto, not detectable in bulk solvent, are the result of an interplay between self- and protein-driven assembly processes that unite inorganic supramolecular and protein chemistry in a host-guest system. Template, nucleation/protection, and catalyst functions of the polypeptide as well as perspectives for designing new clusters are discussed.

PubMed: 22612644
DOI: 10.1021/ja303084n

Experimental method

X-RAY DIFFRACTION (1.6 Å)