Lipm, also known as yqhM in Bacillus subtilis, is an octanoyltransferase. It is essential for the endogenous lipoylation of all lipoate-dependent proteins in B. subtilis, playing a crucial role in the lipoic acid biosynthesis pathway. LipM homologues are present in firmicutes and cyanobacteria. Understanding Lipm's function is important for clarifying the lipoic acid synthesis mechanism in these organisms [1,2].

In B. subtilis, a ΔlipM strain shows that LipM is absolutely required for the endogenous lipoylation of lipoate-dependent proteins. This indicates its vital role in lipoic acid biosynthesis. In contrast to Escherichia coli, B. subtilis requires LipM along with LipL for lipoic acid assembly. E. coli lipB can complement the growth of B. subtilis ΔlipL or ΔlipM strains in the absence of supplements, while an E. coli ΔlipB strain can be complemented with lipM but not lipL. These findings suggest that LipM and LipL catalyze sequential reactions in a novel lipoic acid biosynthesis pathway [1].

In conclusion, LipM is a key enzyme in the lipoic acid biosynthesis pathway in B. subtilis. Studies using gene-knockout-like models in B. subtilis, such as the ΔlipM strain, have revealed its essential role in lipoic acid synthesis, which is fundamental for understanding the metabolic processes related to lipoic acid in bacteria.