Unique lipid composition of Treponema pallidum (Nichols virulent strain)

Abstract

The lipid composition of Treponema pallidum (Nichols virulent strain) was determined after purification of the organisms from the infected testes of corticosteroid-treated rabbits by differential centrifugation, filtration through Nuclepore membranes, and sedimentation in Hypaque density gradients. The total lipids were comprised of 32.2% neutral lipids, mainly cholesterol, and 67.8% phospholipids consisting of phosphatidylcholine (32.1%), sphingomyelin (14.8%), cardiolipin (13.0%), phosphatidylethanolamine (6.2%), phosphatidylinositol-serine (1.2%), and lysophosphatidylcholine (0.4%). Monoglycosyldiglyceride, a glycolipid comprising 25 to 50% of the total lipid of all Treponema previously examined, was not detected. The fatty acid composition was similar but quantitatively distinct from that of the infected testes tissue.Attempts to cultivate Treponema pallidum, the causative agent of syphilis, in vitro have failed since its discovery almost 75 years ago. Largely due to this, little is known about the organism's lipid metabolism or composition. Many cultivable Treponema require long-chain fatty acids for growth (9,16,22) since they can neither synthesize, 8-oxidize, nor desaturate fatty acids (1,10,19). Some intestinal and oral strains, however, can utilize short-chain fatty acids (26). Recent studies suggest that T. pallidum may also have lesions in lipid metabolism similar to many cultivable treponemes (9,18,21,25).Lipids comprise 15 to 20% of the cellular dry weight of the cultivable treponemes (10, 16). The major component is a glycolipid, monoglycosyldiglyceride (MGDG), containing galactose generally as the sugar moiety. MGDG comprises 25 to 50% of the total lipid of each of the approximately 20 treponemal strains of genital, oral, and intestinal origin so far examined (10,16,19) including T. hyodysenteriae (our unpublished data), the only cultivable pathogenic Treponema (12). Although Vaczi et al. (29) investigated the lipid composition of T. pallidum (Budapest strain), as well as four cultivable treponemes, they reported no quantitative data about the individual lipids or gave any indication of the glycolipid content of the organisms.Since T. pallidum cannot be cultivated in vitro, the organism is obtained for laboratory studies from the testes of experimentally infected rabbits. A major impedance of research on T. pallidum is the difficulty of obtaining large yields of the organism free of rabbit testicular material. In recent years, however, the use of corticosteroid-treated rabbits (8), Nuclepore filters (25), and Hypaque gradients (2) has proven remarkably useful in reducing this problem. We have used all of these tools to obtain high numbers of purified T. pallidum for lipid analysis. Infected rabbit testicular tissue and T. phagedenis biotype reiterii were also examined as comparative controls. Our results have shown that T. pallidum appears to be unique among Treponema in that the major lipid component of other Treponema, namely MGDG, was not detected in this human pathogen.MATERIALS AND METHODS C...

Functional analysis of a lipid galactosyltransferase synthesizing the major envelope lipid in the Lyme disease spirocheteBorrelia burgdorferi

“…In addition, proteins with high similarity were found in the spirochetes Treponema denticola and Leptospira interrogans. However, no homolog to mgs was present in T. pallidum (Nichols strain), in agreement with the absence of MGlc-DAG in this species (Matthews et al, 1979). Among the identified homologs were also proteins from thermophiles, Archaea, and photosynthetic bacteria (data not shown).…”

Treponema innocens lipids and further description of an unusual galactolipid of Treponema hyodysenteriae

“…Whereas both species contained monoglycosyldiglyceride, the sugar moiety was 100% glucose in T. innocens and 100% galactose in T. hyodysenteriae (18). Monoglycosyldiglyceride has been reported in all Treponema examined (15) except T. pallidum (17) and in all of the Spirochaetales (14)(15)(16)19) except Leptospira (7). Galactose is usually present as the only sugar moiety, or galactose predominates in combination with glucose (15).…”

Applications of cellular fatty acid analysis.

“…Treponema pallidum purified from rabbit testicular tissue has been inconclusively analyzed in regard to CFA content. The CFAs found (mainly C16:0, C18:1, C18:0, and C18:2) were present in the bacteria but were also found in smaller amounts in uninfected tissue (92). Up to 50% of the total CFAs in Leptospira spp.…”