Project description:The molecular mechanism by which a mycobacterial virus escapes the host bacterial defense and kills the human pathogen Mycobacterium tuberculosis is greatly unclear. Here we report that the gene gp48 of mycobacteriophage A4ZJ24, encoding a metallophosphoesterase-like protein, is required for the killing of M. tuberculosis, but not for M. smegmatis. Gp48 is expressed in the early stage of phage infection and disrupts the mycobacterial chromosomal DNA, and thus silences the expression of multiple anti-phage defensive genes, which only exist in the genome of M. tuberculosis but not in M. smegmatis. The gp48-deleted phage can normally adsorp and invade into M. tuberculosis, however, it does not prevent from activating anti-phage genes, resulting in a loss of its genome DNA replication ability in M. tuberculosis. This study identifies a phage’s metallophosphoesterase as a new determinant of the viral host range and discovered a previously unknown molecular mechanism for mycobacteriophages to kill M. tuberculosis. Our study fills a major gap in current knowledge of the interaction between mycobacterial viruses and M. tuberculosis.
Project description:Viral genomes are most vulnerable to cellular defenses at the start of the infection. A family of jumbo phages related to phage ΦKZ, which infects Pseudomonas aeruginosa, assembles a protein-based phage nucleus to protect replicating phage DNA, but how it is protected prior to phage nucleus assembly is unclear. We find that host proteins related to membrane and lipid biology interact with injected phage protein, clustering in an early phage infection (EPI) vesicle. The injected virion RNA polymerase (vRNAP) executes early gene expression until phage genome separation from the vRNAP and the EPI vesicle, moving into the nascent proteinaceous phage nucleus. Enzymes involved in DNA replication and CRISPR/restriction immune nucleases are excluded by the EPI vesicle. We propose that the EPI vesicle is rapidly constructed with injected phage proteins, phage DNA, host lipids, and host membrane proteins to enable genome protection, early transcription, localized translation, and to ensure faithful genome transfer to the proteinaceous nucleus.
Project description:Viral genomes are most vulnerable to cellular defenses at the start of the infection. A family of jumbo phages related to phage ΦKZ, which infects Pseudomonas aeruginosa, assembles a protein-based phage nucleus to protect replicating phage DNA, but how it is protected prior to phage nucleus assembly is unclear. We find that host proteins related to membrane and lipid biology interact with injected phage protein, clustering in an early phage infection (EPI) vesicle. The injected virion RNA polymerase (vRNAP) executes early gene expression until phage genome separation from the vRNAP and the EPI vesicle, moving into the nascent proteinaceous phage nucleus. Enzymes involved in DNA replication and CRISPR/restriction immune nucleases are excluded by the EPI vesicle. We propose that the EPI vesicle is rapidly constructed with injected phage proteins, phage DNA, host lipids, and host membrane proteins to enable genome protection, early transcription, localized translation, and to ensure faithful genome transfer to the proteinaceous nucleus.