Type IV Secretion Systems and Conjugation in Gram-Negative Pathogens

Gram-negative pathogens such as Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa are the leading causes of hospital-acquired infections worldwide. A commonality among these pathogens is their widespread antibiotic resistance, posing a significant challenge to public health. Bacterial conjugation, as a mechanism of horizontal gene transfer, plays a crucial role in the spread of antibiotic resistance. Among these pathogens, the presence of type IV secretion systems (T4SSs) is particularly notable, as they are involved in the DNA conjugation process. In this review, we first describe the structure and conjugation process of T4SSs, aiming to introduce the current understanding of the involvement of T4SSs in the dissemination of antibiotic resistance in these four pathogens. We further attempt to address questions regarding the role of T4SSs in antibiotic resistance. We will also briefly discuss how T4SSs can be potential therapeutic targets.