biostudies-literatureBaral SNational Institute of Allergy and Infectious DiseasesNIGMS NIH HHS521-537https://www.ebi.ac.uk/biostudies/studies/S-EPMC12675982biostudies-literatureUnknown124(6)By regulating the assortment and abundance of its virulence factors at different anatomic sites, the group A Streptococcus (GAS) can cause a range of human diseases. The Fas regulatory system is encoded by a four-gene locus, fasBCAX, with fasX encoding the FasX small regulatory RNA effector molecule. FasX post-transcriptionally regulates target mRNAs through well-characterized mechanisms. Less characterized are the layers of regulation that occur upstream of FasX activity, such as how the products of the fasBCA genes enhance FasX abundance 100-fold. Here, we present data consistent with FasBCA forming a three-component regulatory system, with FasBC being sensor kinase-like proteins that, upon recognizing one or more signals, heterodimerize and phosphorylate FasA, with phosphorylated FasA bMolecular microbiologyMolecular Characterization of the Group A Streptococcus Virulence-Regulatory System FasBCAX.PMC12675982R21AI163230GM103440Prabhu ARoshika RWoolsey RBaral STal-Gan YSumby PSingh AJain IQuilici DRenshaw CPfalseMolecular Characterization of the Group A Streptococcus Virulence-Regulatory System FasBCAX.By regulating the assortment and abundance of its virulence factors at different anatomic sites, the group A Streptococcus (GAS) can cause a range of human diseases. The Fas regulatory system is encoded by a four-gene locus, fasBCAX, with fasX encoding the FasX small regulatory RNA effector molecule. FasX post-transcriptionally regulates target mRNAs through well-characterized mechanisms. Less characterized are the layers of regulation that occur upstream of FasX activity, such as how the products of the fasBCA genes enhance FasX abundance 100-fold. Here, we present data consistent with FasBCA forming a three-component regulatory system, with FasBC being sensor kinase-like proteins that, upon recognizing one or more signals, heterodimerize and phosphorylate FasA, with phosphorylated FasA b2025-01-01T00:00:00Z2025 Dec2026-06-05T22:18:15.785Z2026-05-22T03:15:27.013ZS-EPMC126759824110855110.1111/mmi.70029