Glycerol-3-phosphate acquisition in spirochetes:: Distribution and biological activity of glycerophosphodiester phosphodiesterase (GlpQ) among Borrelia species

Relapsing-fever spirochetes achieve high cell densities (>10(8)/ml) in their host's blue, while Lye disease spirochetes do not (<10(5)/ml). This striking contrast in pathogenicity of these two groups of bacteria suggests a fundamental difference in their ability tat either exploit or survive in blood. Borrelia hermsii, a tick-borne relapsing-fever spirochete, contains orthologs to glpQ and glpT, genes that encode glycerophosphodiester phosphodiesterase (GlpQ) and glycerol-3-phosphate transporter (GlpT), respectively. In other bacteria, GlpQ hydrolyzes deacylated phospholipids to glycerol-3-phosphate (GP) while GlpT transports G3P into the cytoplasm. Enzyme assays on 17 isolates of borreliae demonstrated GlpQ activity relapsing-fever spirochetes but not in Lyme disease spirochetes. Southern blots demonstrated glpQ and glpT in all relapsing-fever spirochetes but not in the ye disease group. A Lye disease spirochete, Borrelia burgdorferi, that was transformed with a shuttle rector containing glpTQ front B. hermsii produced active enzyme, which demonstrated the association of glpQ with the hydrolysis of phospholipids. Sequence analysis of B. hermsii identified glpF, glpK, ana glpA, which encode the glycerol facilitator, glycerol kinase, and glycerol-3-phosphate dehydrogenase, respectively, all of which are present in B. burgdorferi. All spirochetes mined had gpsA, which encodes the enzyme that reduces dihydroxyacetone phosphate (DHAP) to G3P. Consequently, three pathways for the acquisition of G3P exist among borreliae. (I) hydrolysis of deacylated phospholipids, (ii) reduction of DID, and (ill) uptake and phosphorylation of glycerol. The unique ability of relapsing-fever spirochetes to hydrolyze phospolipids may contribute to their higher cell densities in blood than those of Lyme disease spirochetes.