4x9n
Dithionite reduced L-alpha-Glycerophosphate Oxidase from Mycoplasma pneumoniae with FAD bound
Structural highlights
FunctionGLPO_MYCPN Catalyzes the oxidation of glycerol 3-phosphate to dihydroxyacetone phosphate (DHAP), with a reduction of O2 to H2O2. The formation of hydrogen peroxide by this enzyme is crucial for cytotoxic effects of M.pneumoniae on host cells. Is involved in the metabolism of glycerol and is essential for glycerol utilization; glycerol is one of the few carbon sources that can be utilized by M.pneumoniae for growth (PubMed:19028882). To a lesser extent, is also able to use glyceraldehyde 3-phosphate (GAP), an intermediate in the glycolysis pathway, as a substrate (but the structure of the product has not been elucidated). Therefore, in the absence of glycerol, GAP may serve as a substrate in the GlpO reaction to supply H2O2 during mycoplasma infection (PubMed:25712468). Does not show any dehydrogenase activity with NAD(+) (PubMed:19028882).[1] [2] Publication Abstract from PubMedThe formation of hydrogen peroxide (H2 O2 ) by the FAD-dependent alpha-glycerophosphate oxidase (GlpO), is important for the pathogenesis of Streptococcus pneumoniae and Mycoplasma pneumoniae. The structurally known GlpO from Streptococcus sp. (SspGlpO) is similar to the pneumococcal protein (SpGlpO) and provides a guide for drug design against that target. However, M. pneumoniae GlpO (MpGlpO), having <20% sequence identity with structurally known GlpOs, appears to represent a second type of GlpO we designate as Type II GlpOs. Here, the recombinant His-tagged MpGlpO structure is described at ~2.5 A resolution, solved by molecular replacement using as a search model the Bordetella pertussis protein 3253 (Bp3253) a protein of unknown function solved by structural genomics efforts. Recombinant MpGlpO is an active oxidase with a turnover number of ~580 min-1 while Bp3253 showed no GlpO activity. No substantial differences exist between the oxidized and dithionite-reduced MpGlpO structures. Although, no liganded structures were determined, a comparison with the tartrate-bound Bp3253 structure and consideration of residue conservation patterns guided the construction of a model for alpha-glycerophosphate (Glp) recognition and turnover by MpGlpO. The predicted binding mode also appears relevant for the type I GlpOs (such as SspGlpO) despite differences in substrate recognition residues, and it implicates a histidine conserved in type I and II Glp oxidases and dehydrogenases as the catalytic acid/base. This work provides a solid foundation for guiding further studies of the mitochondrial Glp dehydrogenases as well as for continued studies of M. pneumoniae and S. pneumoniae glycerol metabolism and the development of novel therapeutics targeting MpGlpO and SpGlpO. This article is protected by copyright. All rights reserved. Structure and proposed mechanism of alpha-glycerophosphate oxidase from Mycoplasma pneumoniae.,Elkhal CK, Kean K, Parsonage D, Maenpuen S, Chaiyen P, Claiborne A, Karplus PA FEBS J. 2015 Feb 16. doi: 10.1111/febs.13233. PMID:25688572[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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