Abstract Objective The Type VI Secretion System (T6SS) is a contractile apparatus made of several proteins playing a significant role in the fitness and virulence of many Gram-negative bacteria. The SPI-19 T6SS gene cluster is a virulence factor of Salmonella Dublin contributing to host colonization and antibacterial activity. Previously, we demonstrated that SEDRS06335 (an Rhs protein with a C-terminal M91 domain) is responsible for antibacterial activity of the T6SS SPI−19 ; however, the role of the M91 domain in this phenotype is unknown. Thus, the objective of this study is to provide experimental evidence that the antibacterial activity of SEDRS06335 effector is attributable to its C-terminal M91 domain. Results Here, we determine through interbacterial competition and heterologous expression assays that M91 domain of SEDRS06335 displays antibacterial activity. Furthermore, a three-dimensional structural model of M91 domain revealed a high similarity with the metallopeptidase neurotoxin type A (BotA) from Clostridium botulinum. Interestingly, our results suggest that the M91 domain is responsible for the antibacterial activity of the SEDRS06335 effector in Salmonella Dublin.
Río et al. (Thu,) studied this question.