title: Transfer of R388 derivatives by a pathogenesis-associated type IV secretion system into both bacteria and human cells.
abstract: Bacterial type IV secretion systems (T4SSs) are involved in processes such as bacterial conjugation and protein translocation to animal cells. In this work, we have switched the substrates of T4SSs involved in pathogenicity for DNA transfer. Plasmids containing part of the conjugative machinery of plasmid R388 were transferred by the T4SS of human facultative intracellular pathogen Bartonella henselae to both recipient bacteria and human vascular endothelial cells. About 2% of the human cells expressed a green fluorescent protein (GFP) gene from the plasmid. Plasmids of different sizes were transferred with similar efficiencies. B. henselae codes for two T4SSs: VirB/VirD4 and Trw. A ΔvirB mutant strain was transfer deficient, while a ΔtrwE mutant was only slightly impaired in DNA transfer. DNA transfer was in all cases dependent on protein TrwC of R388, the conjugative relaxase, implying that it occurs by a conjugation-like mechanism. A DNA helicase-deficient mutant of TrwC could not promote DNA transfer. In the absence of TrwB, the coupling protein of R388, DNA transfer efficiency dropped 1 log. The same low efficiency was obtained with a TrwB point mutation in the region involved in interaction with the T4SS. TrwB interacted with VirB10 in a bacterial two-hybrid assay, suggesting that it may act as the recruiter of the R388 substrate for the VirB/VirD4 T4SS. A TrwB ATPase mutant behaved as dominant negative, dropping DNA transfer efficiency to almost null levels. B. henselae bacteria recovered from infected human cells could transfer the mobilizable plasmid into recipient Escherichia coli under certain conditions, underscoring the versatility of T4SSs.
authors: Departamento de Biología Molecular, Facultad Universidad de Cantabria, and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), UC-SODERCAN-CSIC, C. Herrera Oria s/n, 39011 Santander, Spain.
authors: Esther
authors: E
authors: Fernández-González
authors: Héctor D
authors: HD
authors: de Paz
authors: Anabel
authors: A
authors: Alperi
authors: Leticia
authors: L
authors: Agúndez
authors: Marco
authors: M
authors: Faustmann
authors: Félix J
authors: FJ
authors: Sangari
authors: Christoph
authors: C
authors: Dehio
authors: Matxalen
authors: M
authors: Llosa
mesh_terms: D016917:Angiomatosis, Bacillary / Q000235:genetics / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D018416:Bartonella henselae / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D002460:Cell Line; D003227:Conjugation, Genetic; D042783:Endothelial Cells / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems