Bacterial Open Reading Frame-112 Gene Expression induces Mammalian Cell Instability

The soil bacterium Streptomyces rochei is well-known for its anti-bacterial/fungal defense activities. The Open Reading Frame-112 (ORF-112) gene resided in the large linear plasmid pSLA2-L, which encodes a hypothetical 218 amino acid protein of unknown function. In this work, we explored cellular functionality in Eukaryotic cells. The ORF-112 gene was synthesized by tagging GFP (Green fluorescent protein) tag at the N-terminal, then sub-cloned into the mammalian plasmid pMAX-GFP. The protein expression and cellular localisation of GFP-ORF-112 were monitored in COS-7 cell line, using a fluorescent microscope. We have observed a concentrated peri-nuclear aggregation of GFP-ORF-112. In contrast, the control GFP expression exhibited a uniform cytoplasmic/nuclear expression. Notably, the expression of GFP-ORF-112 resulted in significant distortion of overall cell morphology. In addition, we have observed the detachment of cells, cell-rounding and cell floating feature, which is commonly associated with abnormal cell stress. These observations suggest that the expression of GFP-ORF-112 induces cellular toxicity or instability in mammalian cells.