Comparative proteomics analysis of extracellular proteins from Listeria monocytogenes and its isogenic prfA deletion mutant

Abstract:

Abstract:［Objective］ Positive regulatory factor A (PrfA) protein plays a key role in the pathogenicity of Listeria monocytogenes by regulating the expression of virulence genes．We studied the regulation functions of PrfA and its role in Listeria monocytogenes (Lm) virulence． ［Method］Extracellular proteins were obtained from the supernatants of parental strain LM4 and mutant strain LM4ΔprfA cultured in minimal medium． We used two-dimensional gel electrophoresis and matrix associated laser dissociation/ionization time of flight mass spectrometry (MALDI- TOF-MS) to analyze the differences of secreted proteins between LM4 and LM4ΔprfA．［Results］The electrophoresis results show that 31 different spots，19 spots corresponding 12 proteins were identified by MALDI- TOF-MS． Some virulence related proteins were verified，such as InlC，ActA and LLO． Some new proteins that are regulated by PrfA include D-alanyl-D-alanine carboxypeptidase，dipeptide Glycine and Trytophan (GW) repeat-containing surface protein，transcriptional regulator and some hypothetical proteins with unknown functions． Real-time quantitative PCR was conducted to verify the proteomics results． The mRNA expression level of hly，actA and inlC gene was significantly reduced，and that of D-alanyl-D-alanine carboxypeptidase and GW repeat-containing surface protein's synthesis also had a reduction in LM4ΔprfA strain． ［Conclusion］PrfA plays key roles on the regulation of genes in LIPI- I and LIPI- II．