Negatively regulates the transcription of the flagellar master operon flhDC by binding to the upstream region of the operon. The expression of the hdfR gene is negatively regulated by H-NS. Belongs to the LysR transcriptional regulatory family. Was originally thought to be involved in the expression of the phosphatidylserine synthetase pssA. Produces two separate ORFs. Produces two separate ORFs.