https://www.imperial.ac.uk/news/237077/bacterial-intimacy-insights-could-help-tackle/

Important insights into the process by which antibiotic resistance may be acquired by bacteria. Researchers at Imperial College London discovered that the exchange of DNA via conjugation is mediated by a protein from the donor bacteria, termed TraN, which acts as a ‘plug’ to attach itself to a unique outer membrane receptor, or ‘socket’, in recipient bacteria. DNA packets called ‘plasmids’ can then be exchanged. The genes contained by certain plasmids can include coding for resistance to antimicrobial drugs.