DNA-membrane complex: macromolecular content and stimulation of enzymatic activity by polyadenylic acid.

A DNA-cell membrane complex has been isolated from cell suspensions of virulent pneumococci by sarcosyl lysis followed by centrifugation on a sucrose gradient. When polyadenylic acid plus the eight naturally occurring deoxyribonucleosides and deoxyribonucleotides are added to cell suspensions, the percentage of total DNA in the complex increases with incubation time. This increase is not observed in unsupplemented cell suspensions. However, the percentages of RNA, protein, and phospholipid do not increase with incubation time in either supplemented or control complexes. A variety of deoxyribonucleotide kinases and the DNA polymerase are also detected in the DNA-membrane complex, and their specific activities are greater in complexes extracted from supplemented cell suspensions than in those extracted from controls.