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Exploring Directionality and Kinetics of a Bacterial Type IV Secretion System
Author(s) -
Akinleye Olukemi,
Gemechu Betelhem,
Ali Sabrina,
Berkmen Melanie
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.03474
Subject(s) - bacterial conjugation , plasmid , secretion , dna , transfer dna , bacillus subtilis , bacteria , exogenous dna , directionality , biology , chemistry , microbiology and biotechnology , biophysics , genetics , biochemistry , gene , transformation (genetics) , agrobacterium tumefaciens
Type IV Secretion Systems (T4SSs) are large multimeric protein complexes that secrete diverse substrates across a donor cell membrane. While some pathogenic bacteria use T4SSs to secrete virulence factors into host cells, many bacteria utilize T4SSs to transfer DNA from donor to recipient cell during the process of conjugation. T4SSs can not only transfer their cognate conjugative DNA element, they can mobilize resident plasmids that do not encode their own dedicated conjugation machinery. Here, we have studied the kinetics and directionality of DNA transfer by the T4SS encoded by the conjugative element ICE Bs1 of the bacterium Bacillus subtilis . Prior research has shown that ICE Bs1 supports very high conjugation and plasmid mobilization frequencies. We compared the timing and frequency of ICE Bs1 ‐dependent conjugation and plasmid mobilization. We mixed donor and recipients cells, each containing a mobilizable plasmid with a different antibiotic resistance marker, and placed them on solid filters for various periods of time to allow for DNA transfer. The cell mixtures were then transferred to selective media to measure the frequency of DNA transfer. Mating and plasmid mobilization were found to occur within 2 minutes and peaked after 1‐2 hours. Reverse mobilization, in which the donor receives DNA from the recipient, was found to occur after 1‐2 hours and was at least 2 logs less frequent than mating. As expected, reverse mobilization involved a two‐step process, in which the conjugative DNA element is first transferred from the donor to the recipient, allowing the recipient to then produce its own T4SS and transfer DNA back to the donor.