VpsR appears superficially to be a response regulator, based on extension of its alignment to response regulators AlgB and NrtC all the way to the N-terminus. Instead of being a response regulator with a histidine kinase partner, the sigma-54-dependent transcription factor VpsR directly binds to cyclic-di-GMP. Its regulon includes genes for the biosynthesis of the biofilm matrix component called Vibrio polysaccharide (VPS).

1: VpsR, a Member of the Response Regulators of the Two-Component Regulatory Systems, Is Required for Expression of vps Biosynthesis Genes and EPS(ETr)-Associated Phenotypes in Vibrio cholerae O1 El Tor. Yildiz FH, Dolganov NA, Schoolnik GK; J Bacteriol. 2001;183:1716-1726. PMID:11160103