Conjugative type IV secretion in Gram-positive pathogens: TraG, a lytic transglycosylase and endopeptidase, interacts with translocation channel protein TraM
| Autor: | Sabrina Büttner, Lisa Schaden, Günther Koraimann, Verena Kohler, Ines Probst, Elisabeth Grohmann, Walter Keller, Gerald N. Rechberger, Andreas Aufschnaiter |
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| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
030106 microbiology CHAP domain Enterococcus faecalis Type IV Secretion Systems 03 medical and health sciences chemistry.chemical_compound Endopeptidase activity Plasmid Bacterial Proteins Protein Domains Cell Wall Endopeptidases Secretion Molecular Biology Sequence Deletion Binding Sites Base Sequence biology Wild type Biological Transport Gene Expression Regulation Bacterial biology.organism_classification Transmembrane domain chemistry Biochemistry Conjugation Genetic Peptidoglycan Glycosyltransferase Peptidoglycan Carrier Proteins Plasmids Protein Binding |
| Zdroj: | Plasmid. 91:9-18 |
| ISSN: | 0147-619X |
| DOI: | 10.1016/j.plasmid.2017.02.002 |
| Popis: | Conjugative transfer plays a major role in the transmission of antibiotic resistance in bacteria. pIP501 is a Gram-positive conjugative model plasmid with the broadest transfer host-range known so far and is frequently found in Enterococcus faecalis and Enterococcus faecium clinical isolates. The pIP501 type IV secretion system is encoded by 15 transfer genes. In this work, we focus on the VirB1-like protein TraG, a modular peptidoglycan metabolizing enzyme, and the VirB8-homolog TraM, a potential member of the translocation channel. By providing full-length traG in trans, but not with a truncated variant, we achieved full recovery of wild type transfer efficiency in the traG-knockout mutant E. faecalis pIP501ΔtraG. With peptidoglycan digestion experiments and tandem mass spectrometry we could assign lytic transglycosylase and endopeptidase activity to TraG, with the CHAP domain alone displaying endopeptidase activity. We identified a novel interaction between TraG and TraM in a bacterial-2-hybrid assay. In addition we found that both proteins localize in focal spots at the E. faecalis cell membrane using immunostaining and fluorescence microscopy. Extracellular protease digestion to evaluate protein cell surface exposure revealed that correct membrane localization of TraM requires the transmembrane helix of TraG. Thus, we suggest an essential role for TraG in the assembly of the pIP501 type IV secretion system. |
| Databáze: | OpenAIRE |
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