The activity of the CIII regulator of lambdoid bacteriophages resides within a 24-amino acid protein domain

Daniel Kornitzer*, Shoshy Altuvia, Amos B. Oppenheim

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

The CIII protein of lambdoid bacteriophages promotes lysogeny by stabilizing the phage-encoded CII protein, a transcriptional activator of the repressor and integrase genes. We have isolated a set of missense mutations in the cIII gene of phage λ and of phage HK022 that yield inactive CIII proteins. All the mutations are located in the relatively conserved central region of the protein. A comparative analysis of the CIII protein sequence in λ, HK022, and the lambdoid bacteriophage P22 leads us to suggest that this central region assumes an amphipathic α-helical structure. This part of the λ cIII gene was cloned within a fragment of the lacZ gene (the λ-complementing fragment). The resulting fusion protein displays CIII activity. Mutations that yield a nonfunctional fusion protein map within its CIII moiety. These results indicate that the central portion of the CIII protein is both necessary and sufficient for CIII activity.

Original languageAmerican English
Pages (from-to)5217-5221
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume88
Issue number12
StatePublished - 15 Jun 1991

Keywords

  • Antiprotease
  • Fusion protein
  • Lysogenization
  • α-helix

Fingerprint

Dive into the research topics of 'The activity of the CIII regulator of lambdoid bacteriophages resides within a 24-amino acid protein domain'. Together they form a unique fingerprint.

Cite this