2nv0
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(New page: 200px<br /><applet load="2nv0" size="450" color="white" frame="true" align="right" spinBox="true" caption="2nv0, resolution 1.73Å" /> '''Structure of the glu...)
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Revision as of 10:48, 21 November 2007
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Structure of the glutaminase subunit Pdx2 (YaaE) of PLP synthase from Bacillus subtilis
Overview
Vitamin B6 is an essential metabolic cofactor that has more functions in, humans than any other single nutrient. Its de novo biosynthesis occurs, through two mutually exclusive pathways that are absent in animals. The, predominant pathway found in most prokaryotes, fungi, and plants has only, recently been discovered. It is distinguished by a glutamine, amidotransferase, which is remarkable in that it alone can synthesize the, cofactor form, pyridoxal 5'-phosphate (PLP), directly from a triose and a, pentose saccharide and glutamine. Here we report the 3D structure of the, PLP synthase complex with substrate glutamine bound as well as those of, the individual synthase and glutaminase subunits Pdx1 and Pdx2, respectively. The complex is made up of 24 protein units assembled like a, cogwheel, a dodecameric Pdx1 to which 12 Pdx2 subunits attach. In contrast, to the architecture of previously determined glutamine amidotransferases, macromolecular assembly is directed by an N-terminal alpha-helix on the, synthase. Interaction with the synthase subunit leads to glutaminase, activation, resulting in formation of an oxyanion hole, a prerequisite for, catalysis. Mutagenesis permitted identification of the remote glutaminase, and synthase catalytic centers and led us to propose a mechanism whereby, ammonia shuttles between these active sites through a methionine-rich, hydrophobic tunnel.
About this Structure
2NV0 is a Single protein structure of sequence from Bacillus subtilis. Full crystallographic information is available from OCA.
Reference
Structure of a bacterial pyridoxal 5'-phosphate synthase complex., Strohmeier M, Raschle T, Mazurkiewicz J, Rippe K, Sinning I, Fitzpatrick TB, Tews I, Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19284-9. Epub 2006 Dec 11. PMID:17159152
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