The Response Regulator YycF Inhibits Expression of the Fatty Acid Biosynthesis Repressor FabT in Streptococcus pneumoniae

Abstract

The YycFG (also known as WalRK, VicRK, MicAB, or TCS02) two-component system (TCS) is highly conserved among Gram-positive bacteria with a low G+C content. In Streptococcus pneumoniae the YycF response regulator has been reported to be essential due to its control of pcsB gene expression. Previously we showed that overexpression of yycF in S. pneumoniae TIGR4 altered the transcription of genes involved in cell wall metabolism and fatty acid biosynthesis, giving rise to anomalous cell division and increased chain length of membrane fatty acids. Here, we have overexpressed the yycFG system in TIGR4 wild-type strain and yycF in a TIGR4 mutant depleted of YycG, and analyzed their effects on expression of proteins involved in fatty acid biosynthesis during activation of the TCS. We demonstrate that transcription of the fab genes and levels of their products were only altered in the YycF overexpressing strain, indicating that the unphosphorylated form of YycF is involved in the regulation of fatty acid biosynthesis. In addition, DNA-binding assays and in vitro transcription experiments with purified YycF and the promoter region of the FabTH-acp operon support a direct inhibition of transcription of the FabT repressor by YycF, thus confirming the role of the unphosphorylated form in transcriptional regulation.

Characterization of the Mechanisms of Daptomycin Resistance among Gram-Positive Bacterial Pathogens by Multidimensional Lipidomics

“…Multiprotein resistance factor (MprF) performs lysinylation of PGs to form lysyl-PGs and is also responsible for the flipping of lysyl-PGs from the inner to the outer membrane leaflet. Furthermore, YycG (also known as WalK or VicK) is a histidine kinase in the YycFG (or WalRK or VicRK) two-component system that regulates cell wall metabolism and FA biosynthesis ( 44 – 47 ). Thus, one would expect significant changes in the lipid metabolism of the N315-D8 strain.…”

“…Daptomycin-resistant S. aureus with mutations in yycFG frequently have thickened cell walls, which are thought to arise because of reduced autolysin activity as a result of the yycFG mutations ( 17 , 23 , 52 , 53 ). In Streptococcus pneumoniae , YycFG has been shown to regulate FA biosynthesis genes and alter cell membrane composition ( 46 , 47 ). While the role of YycFG in FA biosynthesis has not been confirmed in S. aureus , whether or not it contributes to the significant elevation of selected FFA species, particularly longer 19:0 to 21:0 FAs ( Fig.…”

Arachidonic Acid Stress Impacts Pneumococcal Fatty Acid Homeostasis

“…The cluster harboring this gene (SPD_1871-76) has previously been shown to be regulated by YycFG, a global two-component regulator (Ng et al, 2003 ). YycFG has also been shown to regulate fabT , with overexpression of YycF resulting in an altered cellular fatty acid composition (Mohedano et al, 2005 , 2016 ). As a consequence, we cannot exclude the possibility that fabM may be co-regulated by other systems such as YycFG.…”

More Than a Pore: A Current Perspective on the In Vivo Mode of Action of the Lipopeptide Antibiotic Daptomycin

“…The WalKR two-component system has many different functions in cell wall and membrane homoeostasis as well as cell division [154,155]. Interestingly, WalKR is involved in regulation of autolysis in B. subtilis [156] and in the regulation of membrane fluidity in S. pneumoniae [157]. Moreover, the lipid desaturase, Des, which reduces membrane fluidity in B. subtilis [158], was found to play a role for daptomycin susceptibility in this organism [43].…”