4mnd
From Proteopedia
Crystal structure of Archaeoglobus fulgidus IPCT-DIPPS bifunctional membrane protein
Structural highlights
Function[DIPPS_ARCFU] Involved in biosynthesis of di-myo-inositol phosphate (DIP), a widespread organic solute in microorganisms adapted to hot environments. Catalyzes the condensation of CTP and L-myo-inositol-1-phosphate into CDP-L-myo-inositol, as well as the biosynthesis of di-myo-inositol-1,3'-phosphate-1'-phosphate (DIPP) from CDP-L-myo-inositol and L-myo-inositol-1-phosphate. The cytidylyltransferase is absolutely specific for CTP and L-myo-inositol-1-P. The DIPP synthase uses only L-myoinositol-1-phosphate as an alcohol acceptor, but CDP-glycerol, as well as CDP-L-myo-inositol and CDP-D-myoinositol, are recognized as alcohol donors.[1] [2] [3] Publication Abstract from PubMedPhospholipids have major roles in the structure and function of all cell membranes. Most integral membrane proteins from the large CDP-alcohol phosphatidyltransferase family are involved in phospholipid biosynthesis across the three domains of life. They share a conserved sequence pattern and catalyse the displacement of CMP from a CDP-alcohol by a second alcohol. Here we report the crystal structure of a bifunctional enzyme comprising a cytoplasmic nucleotidyltransferase domain (IPCT) fused with a membrane CDP-alcohol phosphotransferase domain (DIPPS) at 2.65 A resolution. The bifunctional protein dimerizes through the DIPPS domains, each comprising six transmembrane alpha-helices. The active site cavity is hydrophilic and widely open to the cytoplasm with a magnesium ion surrounded by four highly conserved aspartate residues from helices TM2 and TM3. We show that magnesium is essential for the enzymatic activity and is involved in catalysis. Substrates docking is validated by mutagenesis studies, and a structure-based catalytic mechanism is proposed. X-ray structure of a CDP-alcohol phosphatidyltransferase membrane enzyme and insights into its catalytic mechanism.,Nogly P, Gushchin I, Remeeva A, Esteves AM, Borges N, Ma P, Ishchenko A, Grudinin S, Round E, Moraes I, Borshchevskiy V, Santos H, Gordeliy V, Archer M Nat Commun. 2014 Jun 19;5:4169. doi: 10.1038/ncomms5169. PMID:24942835[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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