The Two Acyl Carrier Proteins of Enterococcus faecalis Have Nonredundant Functions

Enterococcus faecalis encodes two proteins, AcpA and AcpB, having the characteristics of acyl carrier proteins (ACPs). We report that the acpA gene located in the fatty acid synthesis operon is essential for fatty acid synthesis and the DacpA strain requires unsaturated fatty acids for growth. The DacpA strain could be complemented by a plasmid carrying a wild-type acpA gene, but not by a plasmid carrying a wild-type acpB gene. Substitution of four AcpA residues for those of AcpB resulted in a protein that modestly complemented the DacpA strain and restored fatty acid synthesis, although the acyl chains synthesized were unusually short.