Disclosed are novel enhancing factor proteins of the PUFA synthase systems, nucleic acid molecules encoding the same, recombinant nucleic acid molecules and recombinant host cells comprising such nucleic acid molecules, genetically modified microorganisms comprising the same, and methods of making and using the same. Also disclosed are genetically modified microorganisms that have been genetically modified to express a PUFA synthase system for the production of PUFAs, wherein the microorganisms have been modified to express the novel enhancing factor proteins of the PUFA synthase system.