Details zur Publikation

Kategorie Textpublikation
Referenztyp Zeitschriften
DOI 10.1128/jb.01047-06
Titel (primär) Lysophosphatidylethanolamine is a substrate for the short-chain alcohol dehydrogenase SocA from Myxococcus xanthus
Autor Avadhani, M.; Geyer, R.; White, D.C.; Shimkets, L.J.
Quelle Journal of Bacteriology
Erscheinungsjahr 2006
Department UMB
Band/Volume 188
Heft 24
Seite von 8543
Seite bis 8550
Sprache englisch
Abstract Short-chain alcohol dehydrogenases (SCADHs) synthesize a variety of intercellular signals and other chemically diverse products. It is difficult to predict the substrate of a SCADH on the basis of amino acid sequence homology, as the substrates are not known for most SCADHs. In Myxococcus xanthus, the SCADH CsgA is responsible for C signaling during fruiting body development, although the mechanism is unclear. Overexpression of the SCADH SocA compensates for the lack of CsgA and restores development and C signaling in csgA mutants. The potential of SocA in generating the C signal enzymatically was explored by developing a dehydrogenase assay-based screen to purify the SocA substrate(s). A SocA substrate was extracted from M. xanthus cells with acidified ethyl acetate and sequentially purified by solid-phase extraction on silica gel and by reverse-phase high-performance liquid chromatography. The fraction with the highest SocA dehydrogenase activity contained the lysophospholipid 1-acyl 2-hydroxy-sn-glycerophosphoethanolamine (lyso-PE) as indicated by the fragment ions and a phosphatidylethanolamine-specific neutral loss scan following liquid chromatography coupled to mass spectrometry. The abundant lysophospholipid with the mass m/z 450 (molecular ion [M-H]-) had a monounsaturated acyl chain with 16 carbons. SocA oxidizes lyso-PE containing either saturated or unsaturated fatty acids but exhibits poor activity on L--glycerophosphorylethanolamine, suggesting that an acyl chain is important for activity. Of the five different head groups, only ethanolamine showed appreciable activity. The apparent K and Vmax for lyso-PE 18:1 were 116 µM and 875 µmol min-1 mg-1, respectively. The catalytic efficiency (kcat/K) was 1 x 108 M-1 s-1. The proposed product, 1-acyloxy-3-(2-aminoethylphosphatyl) acetone was unstable, and the fragmented products were unable to rescue csgA mutant development. The active fraction from thin-layer chromatography also contained an unidentified SocA substrate that had morphogenic properties.
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Avadhani, M., Geyer, R., White, D.C., Shimkets, L.J. (2006):
Lysophosphatidylethanolamine is a substrate for the short-chain alcohol dehydrogenase SocA from Myxococcus xanthus
J. Bacteriol. 188 (24), 8543 - 8550 10.1128/jb.01047-06