No abstract

The herpes simplex virus type 1 (HSV-1) regulatory protein ICP27 is a nuclear phosphoprotein required for viral lytic infection, which acts partly at the posttranscriptional level to affect RNA processing and export. In the present study, we show that ICP27 can interact with itself in vivo. Immunofluorescent staining of cells expressing both an ICP27 mutant with a deletion of the major nuclear localization signal and wild-type ICP27 showed that the mutant protein was efficiently imported into the nucleus in the majority of the cotransfected cells, suggesting heterodimer formation between the wild-type and mutant proteins. Coimmunoprecipitation experiments using epitope-tagged wild-type ICP27 and a series of ICP27 mutants with deletions and insertions in important functional regions of the protein revealed that the C-terminal cysteine-histidine-rich zinc-finger-like region of ICP27 was required for the self-association. Furthermore the self-association was also shown in yeast using two-hybrid assays, and again, an intact C-terminal zinc-finger-like region was required for the interaction. This study provides biochemical evidence that ICP27 may function as a multimer in infected cells.

Natural Bacillus isolates generate limited amounts of surfactin (<10% of their biomass), which functions as an antibiotic or signalling molecule in inter-/intra-specific interactions. However, overproduction of surfactin in Bacillus amyloliquefaciens MT45 was observed at a titre of 2.93 g/l, which is equivalent to half of the maximum biomass. To systemically unravel this efficient biosynthetic process, the genome and transcriptome of this bacterium were compared with those of B. amyloliquefaciens type strain DSM7T. MT45 possesses a smaller genome while containing more unique transporters and resistance-associated genes. Comparative transcriptome analysis revealed notable enrichment of the surfactin synthesis pathway in MT45, including central carbon metabolism and fatty acid biosynthesis to provide sufficient quantities of building precursors. Most importantly, the modular surfactin synthase overexpressed (9 to 49-fold) in MT45 compared to DSM7T suggested efficient surfactin assembly and resulted in the overproduction of surfactin. Furthermore, based on the expression trends observed in the transcriptome, there are multiple potential regulatory genes mediating the expression of surfactin synthase. Thus, the results of the present study provide new insights regarding the synthesis and regulation of surfactin in high-producing strain and enrich the genomic and transcriptomic resources available for B. amyloliquefaciens.