Structural highlights
FunctionMOSB_AZOVD Intracellular storage of molybdenum. Binds polyoxomolybdates. Can bind at least 90 molybdenum atoms per protein molecule. Publication Abstract from PubMedThe molybdenum storage protein (MoSto) can store more than 100 Mo or W atoms as discrete polyoxometalate (POM) clusters. Here, we describe the three POM cluster sites along the threefold axis of the protein complex based on four X-ray structures with slightly different polyoxomolybdate compositions between 1.35 and 2A resolution. In contrast to the Moalpha-out binding site occupied by an Mo3 cluster, the Moalpha-in and Mobeta binding sites contain rather weak and non-uniform electron density for the Mo atoms (but clearly identifiable by anomalous data), suggesting the presence of POM cluster ensembles and/or degradation products of larger aggregates. The "Moalpha-in cluster ensemble" was interpreted as an antiprism-like Mo6 species superimposed with an Mo7 pyramide and the "Mobeta cluster ensemble" as an Mo13 cluster (present mostly in a degraded form) composed of a pyramidal Mo7 and a Mo3 building block linked by three spatially separated MoOx units. Inside the ball-shaped Mo13 cluster sits an occluded central atom, perhaps a metal ion. POM cluster formation at the Moalpha-in and Mobeta sites appears to be driven by filtering out and binding/protecting self-assembled transient species complementary to the protein template. Structural diversity of polyoxomolybdate clusters along the three-fold axis of the molybdenum storage protein.,Poppe J, Warkentin E, Demmer U, Kowalewski B, Dierks T, Schneider K, Ermler U J Inorg Biochem. 2014 Sep;138:122-8. doi: 10.1016/j.jinorgbio.2014.05.009. Epub, 2014 May 28. PMID:24945101[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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