Represses the expression of the yvmC-cypX operon, which is involved in pulcherriminic acid biosynthesis. Also negatively regulates yvmA, yvnB and its own expression. Positively regulates yisI expression. Acts by binding specifically to a 14-bp palindromic motif, the YvmB box, which is present in the promoter region of the target genes. Homodimer. Expression increases during entry into stationary phase. Up-regulated in response to iron starvation. Negatively autoregulated. Also repressed by CcpA in stationary growth phase. Deletion of the gene induces changes of proteins involved in cellular processes depending on iron availability. In iron-rich medium, mutants overproduce a red pigment after entry into the stationary growth phase.