The Essential Response Regulator YyCF Places A Role In Regulating Fatty Acid Biosynthesis And Membrane Composition In Streptococcus pneumoniae

ALTABE, SILVIA GRACIELA

Misiones. Iguazú

Congreso; XL Reunión anual de la SAIB; 2004

SAIB

Abstract: The YycF/G two-component system, originally identified in Bacillus subtilis, is highly conserved among Gram-positive bacteria with a low G+C content. In S. pneumoniae the YycF response regulator has been reported to be essential for cell growth but the signal to which it responds, and the gene members of the regulon, remain unclear. In order to investigate the role of YycF/G in S. pneumoniae, we increased the expression of yycF using a maltose-inducible vector, and analysed genome-wide effects on transcription and protein expression during the course of yycF expression. Induction of yycF expression increased histidine kinase yycG transcript levels, suggesting autoregulation of the yycF/G operon. Evidence from both proteomic and microarray transcriptome studies, as well as analysis of membrane fatty acid composition, indicated that YycF/G is involved in the regulation of fatty acid biosynthesis pathways and in determining the chain length of membrane phospholipids. Our results suggest that YycF influences membrane fluidity and consequently the physical properties of the membrane, which could account for the defects seen in morphology and growth of bacteria during steady state expression of yycF. In agreement with recent transcriptome data on pneumococcal cells depleted of YycF/G we also identified several other potential members of the YycF/G regulon that are required for virulence and cell wall biosynthesis and  metabolism.