The cytoplasmic loops of AgrC contribute to the quorum-sensing activity of Staphylococcus aureus.
Abstract
In Staphylococcus aureus, the accessory gene regulator (agr) quorum-sensing system is thought to play an important role in biofilm formation. The histidine kinase AgrC is one of the agr system components and activated by the self-generated auto-inducing peptide (AIP), which is released continuously into the extracellular environment during bacterial growth. The extracellular loops (Extra-loops) of AgrC are crucial for AIP binding. Here, we reported that the cytoplasmic loops (Cyto-loops) of AgrC are also involved in Agr activity. We identified S. aureus ST398 clinical isolates containing a naturally occurring single amino acid substitution (lysine to isoleucine) at position 73 of an AgrC Cyto-loop that exhibited significantly stronger biofilm formation and decreased Agr activity compared to the wild-type strain. A constructed strain containing the K73I point mutation in AgrC Cyto-loop continued to show a growth dependent induction of the agr system, although the growth dependent induction was delayed by about 6 h compared to the wild-type. In addition, a series of strains containing deletion mutants of the AgrC Cyto- and Extra-loops were constructed and revealed that the removal of the two Cyto-loops and Extra-loops 2 and 3 tot...Continue Reading
References
Related Concepts
Related Feeds
Biofilms
Biofilms are adherent bacterial communities embedded in a polymer matrix and can cause persistent human infections that are highly resistant to antibiotics. Discover the latest research on Biofilms here.