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Department of Pathobiology, University of Washington, Seattle, Washington 98195
Staphylococcus epidermidis releases factors that activate the HIV-1 long terminal repeat, induce cytokine release, and activate nuclear factor
B in cells of macrophage lineage. The active material had a mass of 34,500 daltons, was inactivated by proteases and partitioned into the phenol layer on hot aqueous phenol extraction, and thus was termed phenol-soluble modulin (PSM). High performance liquid chromatography (HPLC) of crude PSM yielded two peaks of activity designated PSM peak 1 and peak 2. MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) mass spectroscopy indicated the presence of two components in peak 1, which were designated PSM
and PSMβ. Peak 2 contained a single component, designated PSM
. Separation of PSM
and PSMβ in peak 1 could be achieved by a second HPLC procedure. The structure of each component was determined by amino acid sequence analysis and identification and sequencing of their genes. PSM
, PSMβ, and PSM
were 22-, 44-, and 25-amino acid, respectively, strongly hydrophobic polypeptides. PSM
was identified as Staphylococcus epidermidis delta toxin, whereas PSM
and PSMβ exhibited more distant homology to previously described staphylococcal toxins. They appeared to exist as a complex or aggregate with activity greater than the component parts. The properties of the S. epidermidis PSMs suggest that they may contribute to the systemic manifestations of Gram-positive sepsis.
Key Words: Staphylococcus epidermidis HIV-1 long terminal repeat phenol-soluble modulin inflammatory polypeptide nuclear factor
B
Abbreviations used: LTA, lipoteichoic acid; MALDI-TOF, matrix-assisted laser desorption ionization-time of flight; MWCO, molecular weight cut off; NEC, neonatal necrotizing enterocolitis; PSM, phenol-soluble modulin; RLU, relative light units.
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