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Structural and functional properties of the p60 proteins from different Listeria species
1Lehrstuhl für Mikrobiologie, Theodor-Boveri-Institut für Biowissenschaften, Universität Würzburg, Germany.
Abstract:
The major extracellular protein p60 of Listeria monocytogenes seems to be required for this microorganism's adherence to and invasion of 3T6 mouse fibroblasts but not for adherence to human epithelial Caco-2 cells. Western blot analysis with polyclonal antibodies against p60 of L. monocytogenes indicated the presence of cross-reacting proteins in the culture supernatants of all Listeria species. Protein p60 of L. monocytogenes could restore adhesion of the L. monocytogenes mutant RIII (impaired in the synthesis of p60) to mouse fibroblasts more efficiently than that of Listeria grayi. The amino acid sequences of the p60-related proteins of L. innocua, L. ivanovii, L. seeligeri, L. welshimeri, and L. grayi indicated highly conserved regions of about 120 amino acids at both the N-terminal and the C-terminal ends. The middle portions of these proteins, consisting of about 240 amino acids, varied considerably. These parts include the repeat domain consisting of repetitions of Thr (T) and Asn (N) which was present only, albeit in different arrangements, in the p60 proteins of L. monocytogenes and L. innocua. The p60-related proteins of L. grayi, L. ivanovii, L. seeligeri, and L. welshimeri each contained an insertion of 54 amino acids which was absent in the p60 proteins of L. monocytogenes and L. innocua.
Insights
The Listeria monocytogenes p60 protein aids bacterial adherence and invasion in mouse cells but not human cells. Sequence analysis reveals conserved regions and variable domains, including unique repeat structures in some Listeria species.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Pathogenesis
Background:
- The extracellular protein p60 from Listeria monocytogenes is implicated in host cell interactions.
- Understanding p60's role is crucial for deciphering Listeria pathogenesis and host specificity.
Purpose of the Study:
- To investigate the role of Listeria monocytogenes p60 protein in bacterial adherence and invasion.
- To analyze the structural conservation and variation of p60-related proteins across different Listeria species.
Main Methods:
- Western blot analysis using polyclonal antibodies against L. monocytogenes p60.
- Adhesion and invasion assays using L. monocytogenes mutants and various cell lines (3T6 mouse fibroblasts, Caco-2 cells).
- Amino acid sequence comparison of p60-related proteins from multiple Listeria species.
Main Results:
- L. monocytogenes p60 is essential for adherence/invasion of mouse fibroblasts but not human epithelial cells.
- Cross-reacting p60 proteins were detected in all tested Listeria species.
- Sequence analysis revealed conserved N-terminal and C-terminal regions, with variable middle portions containing unique repeat domains in L. monocytogenes and L. innocua.
Conclusions:
- The p60 protein plays a differential role in Listeria-host cell interactions depending on the cell type.
- Structural variations in p60, particularly the repeat domain, may contribute to species-specific adherence and invasion capabilities.
- Further research into p60 structure-function relationships can elucidate Listeria pathogenesis mechanisms.