Lipoglycans (previously designated lipopolysaccharides) from several species of
Acholeplasma
and from
Thermoplasma acidophilum
were examined for endotoxin-like activities as measured by the standard rabbit fever test and the
Limulus
amoebocyte lysate assay. The lipoglycans from
Acholeplasma granularum, Achloplasma laidlawii, Acholeplasma modicum
, and
Acholeplasma oculi
caused a febrile response at concentrations of 1 ng/ml per kg or greater, whereas with control
Escherichia coli
EC-2 lipopolysaccharides, 6.25 ng/ml per kg was required. Similar results were obtained in the
Limulus
amoebocyte lysate test. The minimum concentrations in nanograms per milliliter required to stimulate formation of a solid clot were:
Acholeplasma axanthum
, 0.22;
A. granularum
, 0.85;
A. modicum
, 0.51;
A. laidlawii
, 1.05;
A. oculi
, 0.74. Standard
E. coli
1B lipopolysaccharide required a concentration of 0.125 ng/ml.
Thermoplasma
lipoglycan was least active, requiring 4.25 ng/ml. Clotting of the
Limulus
lysate proceeds by the activation by lipopolysaccharide plus Ca
2+
of a proenzyme which cleaves an arginine-lysine peptide bond of the coagulogen. The clotting and amidase activities are inactivated by deoxycholate and can be reactivated by addition of lipopolysaccharide and Ca
2+
. As with
E. coli
1B lipopolysaccharide, acholeplasmal lipoglycans were shown to restore both clotting and amidase activities of the deoxycholate-inactivated
Limulus
clotting enzyme. The degree of restoration of amidase activity by mycoplasmal lipoglycans relative to
E. coli
lipopolysaccharide (1.00) were:
A. axanthum
, 1.71;
A. modicum
, 1.22;
A. granularum
, 0.61; and
Thermoplasma
, 0.37. The coagulating enzyme, restored with either
E. coli
lipopolysaccharide or mycoplasmal lipoglycans, was able to react with the synthetic peptide benzoyl-Ile-Glu-(γ-OCH
3
)-Gly-p-nitroaniline (an analog of the coagulogen) or with the purified coagulogen itself to form the clot. The mycoplasmal lipoglycans alone were incapable of promoting these reactions when incubated with the synthetic peptide or with the purified coagulogen, thereby ruling out the contamination of these lipoglycans with proteases capable of cleaving the same Arg-Lys peptide bond of the coagulogen. These results show that acholeplasmal lipoglycans possess endotoxin-like activities. Their passive or active role in disease remains to be established.
Different Proteins Mediate Step-Wise Chromosome Architectures in Thermoplasma acidophilum and Pyrobaculum calidifontis
