A Salmonella typhimurium Endonuclease that Converts Native DNA to Fragments of about 8 X 105 daltons

Abstract

319Crude extracts of Salmonella typhimurium were found to contain an endonuclease that degraded double-stranded linear DNA from bacteria and phages to fragments with a molecular weight of about 8 x 105. The nuclease did not have an absolute requirement for Mg2+. One discrete intermediate product had a molecular weight of 6.6 x I O~. Extracts from two different mutants were tested : one completely lacked the endonuclease activity (strain DB5575), and the other showed an absolute requirement for Mg2+ (strain 4543). No biological role has yet been found for this endonuclease of S. typhimurium.

Salmonella typhimurium mutants with reduced levels of transfer ribonucleic acid-inhibitable endodeoxyribonucleolytic activity

“…Extracts of Salmonella typhimurium contain an endonucleolytic activity which introduces scissions into double-stranded DNA molecules (20). The enzyme(s) responsible for this activity has not been purified or characterized.…”