Peptide chaperone involved in the biosynthesis of the enzyme cofactor mycofactocin (MFT). Binds MftA and MftC with high affinity, and is essential for MftC activity on MftA, likely via the formation of a ternary complex (PubMed:27158836) (By similarity). Is required for the in vivo ethanol assimilation in M.smegmatis (PubMed:31113891). Cells lacking this gene lose the ability to utilize ethanol as the sole growth substrate. Belongs to the peptide chaperone MftB family.