Binding of retrovirus-associated protein kinase and proteins to Staphylococcus aureus.

Formalin-fixed Staphylococcus aureus strain Cowan, bearing protein A, routinely used for the absorption of antigen-antibody complexes, was found to bind protein kinase activity from disrupted Moloney murine leukaemia virus (Mo-MuLV). The Wood strain of S. aureus lacking protein A also bound the kinase with similar efficiency. About 50% of the bound kinase activity, as detected by phosphorylation of casein using [gamma-32P]ATP, could be eluted from the bacterial preparation with buffer containing 0 X 5 M-KC1. Similar results were obtained with Moloney murine sarcoma virus (Mo-MuSV) strain 349 and ts110 MuSV(MuLV). The bacterial preparation was also found to bind casein kinase activity from cellular extracts of uninfected, Rauscher murine leukaemia virus (R-MuLV)-infected and Mo-MuLV-infected cells. Analysis of [3H]leucine-labelled proteins from purified virus showed selective binding to S. aureus of only two major labelled virus proteins. One virus component bound to S. aureus had the relative mobility of p15; the other polypeptide co-migrated with virus p10. Upon exposure to increased salt concentration, most of the p10 but very little of the p15 proteins were released. The S. aureus-binding proteins from ts110 Mo-MuSV and MuSV-349 revealed similar binding and elution patterns of p10 and p15 molecules. The p10 and protein kinase activity eluted from Mo-MuLV-absorbed bacteria were separated by gel filtration into a high molecular weight species, containing p10 and kinase activity, and a low molecular weight p10 monomer lacking enzymic activity.