High-density lipoprotein that support Ureaplasma urealyticum growth

• Published in: Journal of bacteriology 1982-01, Vol.151 (2), p.629-635
• Main Authors: Sayed, IA, Sweat, F W
• Format: Article
• Language: English
• Subjects: Ureaplasma urealyticum
• ISSN: 0021-9193

A high-density lipoprotein with growth-promoting activity for U. urealyticum was purified in high yield from equine serum by ammonium sulfate fractionation and molecular filtration. Fractions enriched in growth-promoting activity represented 5% of the total serum protein, and 30 mu g of the purified protein per ml gave an activity equivalent to that from 100 mu g of whole serum per ml. The serum was totally replaced by purified lipoprotein when tested in a soy peptone-yeast dialysate or when added to a chemically defined synthetic medium. Polyacrylamide gel electrophoresis indicated that one major protein with growth-promoting activity is present. A total of 10 proteins were distinguished, with 75% of the total contributed by two proteins with molecular weights of 160,000 and 170,000. A total of 90% of the lipoprotein was an alpha-protein with a mobility of 0.67 in two-dimensional immunoelectrophoresis. The active component was further characterized as high-density lipoprotein. Two components with S = 6.4 and S = 15.8 were distinguished. The growth-promoting activity of delipidized protein was dependent upon the addition of exogenous cholesterol, and ( super(14)C)cholesterol was transferred to ureaplasmic cells in cultures containing the delipidized protein. A major portion of the ( super(14)C)cholesterol remained associated with the protein during filtration on Sepharose 4B columns.