Macroamphiphilic Components of Thermophilic Actinomycetes: Identification of Lipoteichoic Acid in Thermobifida fusca▿ †

The cell envelopes of Gram-positive bacteria contain structurally diverse membrane anchored macroamphiphiles (lipoteichoic acids and lipoglycans), the functions of which are poorly understood. As regulation of membrane composition is an important feature of adaptation to life at higher temperatures, we have examined the nature of the macroamphiphiles present in the thermophilic actinomycetes Thermobifida fusca and Rubrobacter xylanophilus. Following hot-phenol water extraction and purification by hydrophobic interaction chromatography, Western blotting with a monoclonal anti-lipoteichoic acid antibody strongly suggested the presence of a polyglycerophoshate lipoteichoic acid in T. fusca. This structure was confirmed by chemical and NMR analyses which confirmed that the lipoteichoic acid is subsitututed with ß-glucosyl residues, in common with the teichoic acid of this organism. In contrast, several extraction methods failed to recover significant macroamphiphilic carbohydrate or phosphate containing material from R.xylanophilus suggesting that this actinomycete most likely lacks a membrane anchored macroamphiphile. The finding of a polyglycerophosphate lipoteichoic acid in T. fusca suggests that lipoteichoic acids may be more widely present in the cell envelopes of actinomycetes than was previously assumed. However, the apparent absence of macroamphiphile in the cell envelope of R.xylanophilus is highly unusual and suggests that macroamphiphiles may not always be essential for cell envelope homeostasis in Gram-positive bacteria.
JRC.G.7-Traceability and vulnerability assessment