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Updated: May 17, 2026

Heterokaryon Technique for Analysis of Cell Type-specific Localization
Published on: March 11, 2011
Functional eukaryotic nuclear localization signals are widespread in terminal proteins of bacteriophages
Modesto Redrejo-Rodríguez1, Daniel Muñoz-Espín, Isabel Holguera
1Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain.
Abstract:
A number of prokaryotic proteins have been shown to contain nuclear localization signals (NLSs), although its biological role remains sometimes unclear. Terminal proteins (TPs) of bacteriophages prime DNA replication and become covalently linked to the genome ends. We predicted NLSs within the TPs of bacteriophages from diverse families and hosts and, indeed, the TPs of Φ29, Nf, PRD1, Bam35, and Cp-1, out of seven TPs tested, were found to localize to the nucleus when expressed in mammalian cells. Detailed analysis of Φ29 TP led us to identify a bona fide NLS within residues 1-37. Importantly, gene delivery into the eukaryotic nucleus is enhanced by the presence of Φ29 TP attached to the 5' DNA ends. These findings show a common feature of TPs from diverse bacteriophages targeting the eukaryotic nucleus and suggest a possible common function by facilitating the horizontal transfer of genes between prokaryotes and eukaryotes.
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