Disclosing the in vivo organization of a viral histone-like protein in Bacillus subtilis mediated by its capacity to recognize the viral genome

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 109; no. 15; pp. 5723 - 5728
• Main Authors: Holguera, Isabel, Ballesteros-Plaza, David, Muñoz-Espín, Daniel, Salas, Margarita
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 10.04.2012; National Acad Sciences
• Subjects: Bacillus Phages; Bacillus Phages - genetics; Bacillus Phages - metabolism; Bacillus subtilis; Bacillus subtilis - cytology; Bacillus subtilis - virology; bacteria; Bacteriophages; Biological Sciences; Cells; cytology; Deoxyribonucleic acid; DNA; DNA - metabolism; DNA polymerase; DNA replication; DNA Replication - genetics; DNA-directed DNA polymerase; Eukaryotes; fluorescence microscopy; genetics; genome; Genome, Viral; Genome, Viral - genetics; Genomes; Histones; Histones - metabolism; Infections; Life Sciences; metabolism; Microscopy; Models, Biological; Mutant Proteins; Mutant Proteins - metabolism; Protein Binding; Protein Transport; Proteins; Viral DNA; Viral genomes; Viral Proteins; Viral Proteins - metabolism; virology; virus replication
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1203824109

Organization of replicating prokaryotic genomes requires architectural elements that, similarly to eukaryotic systems, induce topological changes such as DNA supercoiling. Bacteriophage Φ29 protein p6 has been described as a histone-like protein that compacts the viral genome by forming a nucleoprotein complex and plays a key role in the initiation of protein-primed DNA replication. In this work, we analyze the subcellular localization of protein p6 by immunofluorescence microscopy and show that, at early infection stages, it localizes in a peripheral helix-like configuration. Later, at middle infection stages, protein p6 is recruited to the bacterial nucleoid. This migrating process is shown to depend on the synthesis of components of the Φ29 DNA replication machinery (i.e., terminal protein and DNA polymerase) needed for the replication of viral DNA, which is required to recruit the bulk of protein p6. Importantly, the double-stranded DNA-binding capacity of protein p6 is essential for its relocalization at the nucleoid. Altogether, the results disclose the in vivo organization of a viral histone-like protein in bacteria.