During growth on glucose, RamB negatively controls the expression of aceA, aceB, ack and pta genes which are involved in acetate metabolism (PubMed:15090522, PubMed:17114251). RamB is also a negative regulator of rpf2 gene expression during growth on acetate as the sole carbon source (PubMed:18355281). RamB represses its own expression. Additionally, ramB expression is subject to carbon source-dependent positive control by RamA. Cells lacking this gene show high-level specific activities of acetate kinase (Ack), phosphotransacetylase (Pta), isocitrate lyase (AceA) and malate synthase (AceB) irrespective of the substrate (PubMed:15090522). The transcription level of the rpf2 gene is increased 20-fold in the ramB deletion mutant during growth on acetate as the sole carbon source (PubMed:18355281). C.glutamicum shows high-level specific activities of acetate kinase (Ack), phosphotransacetylase (Pta), isocitrate lyase (AceA) and malate synthase (AceB) when grown on acetate as sole carbon and energy sources. It shows low-level specific activities with all four enzymes when grown on glucose as sole carbon and energy sources. Belongs to the short-chain fatty acyl-CoA assimilation regulator (ScfR) family.