Subcellular localization and function study of a secreted phospholipase C from Nocardia seriolae

Abstract

Fish nocardiosis is a chronic systemic granulomatous disease, and Nocardia seriolae is the main pathogen that causes this disease. But the pathogenesis and virulence factors of N. seriolae are not fully understood. A phospholipase C (PLC), which was likely to be a secreted protein targeting host cell mitochondria, was found by the bioinformatics analysis on the whole genome sequence of N. seriolae. In order to determine the subcellular localization and study the preliminary function of PLC from N. seriolae (NsPLC), the gene cloning, secreted protein identification, subcellular localization in host cells and apoptosis detection of NsPLC were carried out in this study. The results showed that NsPLC was a secreted protein by mass spectrometry analysis of extracellular products from N. seriolae. Subcellular localization of NsPLC-GFP fusion protein in FHM cells revealed that the green fluorescence exhibited a punctate distribution near the nucleus and did not co-localize with mitochondria. In addition, apoptosis assay suggested that apoptosis was induced in FHM cells by the overexpression of NsPLC. This study may lay the foundation for further study on the function of NsPLC and promote the understanding of the virulence factors and pathogenic mechanism of N. seriolae.

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