How Evelyn Witkin discovered the bacterial SOS response to DNA damage
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Working at Cold Spring Harbor, Evelyn Witkin showed that after UV irradiation of E. coli only about 4 colonies survived per million bacteria, and that survivors' resistance to UV and X-ray radiation rose roughly 100-fold. She proposed that UV switches on at least 43 genes that stay silent in healthy cells and are activated only when DNA is damaged, a coordinated repair program later named the SOS response by Miroslav Radman. The concept built on known repair pathways such as photoreactivation and excision repair, with RecA triggering the repair genes when stalled replication forks expose single-stranded DNA. The account comes from Witkin herself, now at Rutgers University, in an expert commentary published on October 15, 2026.
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- youtube.comEvelyn Witkin of Rutgers University on Discovering the SOS Response in Bacteria
Evelyn Witkin, working at Cold Spring Harbor, found that after UV irradiation of E. coli only 4 colonies survived per million bacteria, with resistance to UV and X-ray radiation raised roughly 100-fold. She proposed that UV activates at least 43 genes that stay silent in healthy cells and turn on when DNA is damaged, forming the SOS response, a DNA damage repair mechanism. The concept, named by Miroslav Radman, was built on repair pathways such as photoreactivation and excision repair, with RecA triggering repair genes when stalled replication forks expose single-strand DNA.
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