Streptococcus mutans SpxA2 relays the signal of cell envelope stress from LiaR to effectors that maintain cell wall and membrane homeostasis

In this study, the role of thespxA2 transcriptional regulator in these two pathways, and overall cell envelope homeostasis, was examined. Loss ofspxA2 resulted in an increase in the proportion of saturated fatty acids in theS. mutans membrane and altered transcription of several genes involved in the production of these membrane fatty acids, includingfabT andfabM. Furthermore, activity of the F1F0‐ATPase was increased in the ∆spxA2 strain. Transcription ofspxA2 was elevated in the presence of a variety of membrane stressors, and highly dependent on theliaR component of the LiaFSR system, which is known to sense cell envelope stress in many Gram ‐positive bacteria. Finally, deletion of ∆spxA2 led to altered susceptibility ofS. mutans to membrane stressors. Overall, the results of this study indicate thatspxA2 serves a crucial role in transmitting the signal of cell wall/membrane damage from the LiaFSR sensor to downstream effectors in the SpxA2 regulon which restore and maintain membrane and cell wall homeostasis.
Source: Molecular Oral Microbiology - Category: Microbiology Authors: Tags: ORIGINAL ARTICLE Source Type: research