This Article Full Text (PDF) Other Versions of this Article: JB.01047-06v1 188/24/8543    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Avadhani, M. Articles by Shimkets, L. J. Search for Related Content PubMed PubMed Citation Articles by Avadhani, M. Articles by Shimkets, L. J.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.01047-06
Copyright (c) 2006, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Lysophosphatidylethanolamine is a Substrate for Short Chain Alcohol Dehydrogenase SocA from Myxococcus xanthus

Department of Microbiology, University of Georgia, Athens GA 30602; Center for Biomarker Analysis and Department of Microbiology, University of Tennessee, Knoxville TN 37932-2575; Department of Environmental Microbiology, UFZ Leipzig-Halle, D-04318, Leipzig, Germany

^* To whom correspondence should be addressed. Email: shimkets{at}uga.edu.

	Abstract

Short chain alcohol dehydrogenases (SCADH) synthesize a variety of intercellular signals and other chemically diverse products. It is difficult to predict the substrate of a SCADH based on amino acid sequence homology as the substrates are not known for most SCADH. 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 (LCSi) and by reverse phase HPLC. The fraction with the highest SocA dehydrogenase activity contained the lysophospholipid 1-acyl 2-hydroxy-sn-glycerophosphoethanolamine (lysoPE) indicated by the fragment ions and a phosphatidylethanolamine (PE)-specific neutral loss scan following liquid chromatography coupled 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 lysoPE 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 5 different head groups, only ethanolamine showed appreciable activity. The apparent K_m and V_max for lyso PE 18:1 were 116 µM and 875 µmol min^-1 mg^-1, respectively. The catalytic efficiency (K_cat/K_m) was 1 x 10⁸ M^-1 sec^-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 TLC also contained an unidentified SocA substrate that had morphogenic properties.

This article has been cited by other articles:

• Viswanathan, P., Murphy, K., Julien, B., Garza, A. G., Kroos, L. (2007). Regulation of dev, an Operon That Includes Genes Essential for Myxococcus xanthus Development and CRISPR-Associated Genes and Repeats. J. Bacteriol. 189: 3738-3750 [Abstract] [Full Text]