Calcium-requiring step in the uptake of deoxyribonucleic acid molecules through the surface of competent pneumococci.
The conversion of surface-adsorbed deoxyribonucleic acid (DNA) molecules to a state in which they are inaccessible to exogenous deoxyribonuclease requires specifically calcium ions; magnesium ions cannot replace calcium ions. Virtually maximal levels of nuclease-resistant DNA binding and genetic transformation can be obtained in media free from magnesium and containing only calcium ions. It is suggested that the calcium-requiring process is the transport of DNA molecules across the plasma membrane. Magnesium ions stimulate both the loss of surface-adsorbed DNA to the medium and the extracellular degradation of DNA.
D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D013296:Streptococcus pneumoniae / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D014170:Transformation, Genetic / Q000187:drug effects*
D004269:DNA, Bacterial; D004492:Edetic Acid; D003851:Deoxyribonucleases; D008274:Magnesium; D002118:Calcium