Lambda Gam protein inhibits the helicase and chi-stimulated recombination activities of Escherichia coli RecBCD enzyme

UMMS Affiliation

Department of Molecular Genetics and Microbiology

Publication Date


Document Type



Amino Acid Sequence; Bacteriophage lambda; Base Sequence; Cloning, Molecular; Conjugation, Genetic; DNA Helicases; DNA Repair; DNA Replication; DNA, Bacterial; DNA, Viral; DNA-Binding Proteins; Escherichia coli; *Escherichia coli Proteins; Exodeoxyribonuclease V; Exodeoxyribonucleases; Molecular Sequence Data; Recombination, Genetic; Ultraviolet Rays; Viral Proteins


Life Sciences | Medicine and Health Sciences


The lambda Gam protein was isolated from cells containing a Gam-producing plasmid. The purified Gam protein was found to bind to RecBCD without displacing any of its subunits. Gam was shown to inhibit all known enzymatic activities of RecBCD: ATP-dependent single- and double-stranded DNA exonucleases, ATP-independent single-stranded endonuclease, and the ATP-dependent helicase. When produced in vivo, Gam inhibited chi-activated recombination in lambda red gam crosses but had little effect on the host's ability to act as a recipient in conjugational recombination. These experiments suggest that RecBCD possesses an additional "unknown" activity that is resistant to or induced by Gam. Additionally, the expression of Gam in recD mutants sensitizes the host to UV irradiation, indicating that Gam alters one or more of the in vivo activities of RecBC(D-).


J Bacteriol. 1991 Sep;173(18):5808-21.

Journal/Book/Conference Title

Journal of bacteriology

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