Prof. Dr. Rotem Sorek

Small peptides that direct communication between phages

Weizmann Institute of Science Rehovot (Israel), Department of Molecular Genetics

Temperate phages can become integrated into the genome of their host bacterial cells, a process called lysogeny. In every infection, temperate phages need to decide whether to replicate and lyse their host or to lysogenize and keep the host viable. We discovered that phages infecting Bacillus bacteria use a small-molecule communication system to coordinate lysis-lysogeny decisions. During infection of its Bacillus host cell, the phage produces a 6aa communication peptide that is released to the medium. In subsequent infections, progeny phages measure the concentration of this peptide and lysogenize if the concentration is sufficiently high. We termed this communication system the “arbitrium” system (“decision” in Latin), and further showed that it is encoded by 3 phage genes: aimP, encoding a µ-protein (43aa) that is processed into the communication peptide; aimR, the intracellular peptide receptor; and aimX, a negative regulator of lysogeny. We found that different phages use µ-proteins to encode different versions of the communication peptide, demonstrating a phage-specific peptide communication code for lysogeny decisions. The aims of this project are to characterize the broad range of phages utilizing arbitrium peptides and understand the diversity and functional roles of arbitrium-encoding µ-proteins in prophage and phage genomes.

  1. Erez Z, Steinberger-Levy I, Shamir M, Doron S, Stokar-Avihail A, Peleg Y, Melamed S, Leavitt A, Savidor A, Albeck S, Amitai G, Sorek R. Communication between viruses guides lysis-lysogeny decisions. Nature, 541(7638):488-493 (2017).
  2. Ofir G, Melamed S, Sberro H, Mukamel Z, Silverman S, Yaakov G, Doron S, Sorek R. DISARM is a widespread bacterial defence system with broad anti-phage activities. Nature Microbiology, in press doi: 10.1038/s41564-017-0051-0. [Epub ahead of print] (2017)
  3. Dar D., Shamir M., Mellin J.R., Koutero M., Stern-Ginossar N., Cossart P., Sorek R. Term-seq reveals abundant ribo-regulation of antibiotics resistance in bacteria. Science, 352(6282):187 (2016).
  4. Dar D, Prasse D, Schmitz RA, Sorek R. Widespread formation of alternative 3′ UTR isoforms via transcription termination in archaea. Nature Microbiology, 1(10):16143 (2016).
  5. Levy A, Goren M.G, Yosef I., Auster O., Manor M., Amitai G., Edgar R., Qimron U., Sorek R. Spacer acquisition biases explain preference for foreign DNA in CRISPR adaptation. Nature, 520(7548):505-10 (2015).