Bacterial type VI secretion system augments resistance against biotic and abiotic stress

Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, India

Abstract

In their natural environment, bacteria employ various mechanisms to survive and protect themselves from neighboring microorganisms. One of the most noteworthy features found in a minority approximately 25% of Gram-negative species, predominantly those inhabiting complex, competitive environment is the type VI secretion system (T6SS). T6SS gene clusters are exclusive to Gram-negative bacteria, with the number of clusters varying from one to six per organism. Bacteria utilize the T6SS to deliver effectors responsible for eliminating their competitors, using a lancet-like apparatus to transport materials outside the cells, ensuring survival in a stressful environment, and subverting host cells. Since its discovery in 2006, research on the T6SS — encompassing biochemical, structural, and molecular studies — has led to the identification and characterization of its assembly, loading, firing, and disassembly processes. Ongoing research, coupled with bioinformatics approaches, is expanding our knowledge of new T6SS effectors and their diverse functionality, shedding light on previously unexplored aspects of prokaryotic and eukaryotic organism biology. The present review focuses on recent discoveries related to T6SS effectors, their mechanisms, and regulation, enhancing our understanding of this combative system.