Regulatory role of CsuR (YiaU) in determination of cell surface properties of K-12.

Genomic SELEX screening was performed to identify the binding sites of YiaU, an uncharacterized LysR family transcription factor, on the K-12 genome. Five high-affinity binding targets of YiaU were identified, all of which were involved in the structures of the bacterial cell surface such as outer and inner membrane proteins, and lipopolysaccharides. Detailed and analyses suggest that YiaU activates these target genes. To gain insight into the effects of YiaU on physiological properties, we used phenotype microarrays, biofilm screening assays and the sensitivity against serum complement analysed using a deletion mutant or YiaU expression strain. Together, these results suggest that the YiaU regulon confers resistance to some antibiotics, and increases biofilm formation and complement sensitivity. We propose renaming YiaU as CsuR (regulator of cell surface).