RESUMEN
Over the past decade, thousands of bacteriophage genomes have been sequenced and annotated. A striking observation from this work is that known structural features and functions cannot be assigned for >65% of the encoded proteins. One approach to begin experimentally elucidating the function of these uncharacterized gene products is genome-wide screening to identify phage genes that confer phenotypes of interest like inhibition of host growth. This study describes the results of a screen evaluating the effects of overexpressing each gene encoded by the temperate Cluster F1 mycobacteriophage Girr on the growth of the host bacterium Mycobacterium smegmatis. Overexpression of 29 of the 102 Girr genes (~28% of the genome) resulted in mild to severe cytotoxicity. Of the 29 toxic genes described, 12 have no known function and are predominately small proteins of <125 amino acids. Overexpression of the majority of these 12 cytotoxic no known functions proteins resulted in moderate to severe growth reduction and represent novel antimicrobial products. The remaining 17 toxic genes have predicted functions, encoding products involved in phage structure, DNA replication/modification, DNA binding/gene regulation, or other enzymatic activity. Comparison of this dataset with prior genome-wide cytotoxicity screens of mycobacteriophages Waterfoul and Hammy reveals some common functional themes, though several of the predicted Girr functions associated with cytotoxicity in our report, including genes involved in lysogeny, have not been described previously. This study, completed as part of the HHMI-supported SEA-GENES project, highlights the power of parallel, genome-wide overexpression screens to identify novel interactions between phages and their hosts.
Asunto(s)
Genoma Viral , Micobacteriófagos , Mycobacterium smegmatis , Mycobacterium smegmatis/virología , Micobacteriófagos/genética , Proteínas Virales/genética , Proteínas Virales/metabolismoRESUMEN
Secretariat and Hydrus are phages grouped into the DJ cluster that were isolated on Gordonia rubripertincta NRRL B-16540. The phages have 75% nucleotide identity and share 73% gene content. Secretariat has a genome with 84 predicted genes, while Hydrus has 91 predicted genes and can also infect Gordonia terrae 3612.
RESUMEN
Cluster EK2 Akoni, Ashton, and Truong are lytic Podoviridae actinobacteriophages that were isolated from soil in Florida using Microbacterium foliorum NRRL B-24224 as the host. The genomes are 54,307 bp, 54,560 bp, and 54,309 bp, respectively, and are 60% GC rich. Each genome contains a novel 13,464-bp gene that encompasses 25% of the genome.