Lipm, also known as yqhM in Bacillus subtilis, is an octanoyltransferase crucial for lipoic acid biosynthesis. In B. subtilis, lipoic acid is essential for the function of lipoate-dependent proteins. Lipm transfers the octanoyl moiety, which is a key step in the lipoic acid synthesis pathway, and thus is of great biological importance for these bacteria [2,3].

In B. subtilis, a ΔlipM strain demonstrated that LipM is absolutely required for the endogenous lipoylation of all lipoate-dependent proteins, confirming its role as the octanoyltransferase in this bacterium [2]. Unlike in Escherichia coli, B. subtilis requires LipM along with LipL for lipoic acid assembly, as ΔlipL strains cannot synthesize lipoic acid despite having LipM and LipA [2]. Expression of E. coli lipB allows the growth of B. subtilis ΔlipL or ΔlipM strains without supplements, while an E. coli ΔlipB strain can be complemented with lipM but not lipL [2].

In conclusion, LipM is essential for the lipoic acid biosynthesis pathway in B. subtilis, specifically for the octanoyltransfer reaction and subsequent lipoylation of proteins. The study of LipM in B. subtilis models has provided insights into the unique requirements of lipoic acid synthesis in this bacterium, contributing to our understanding of microbial metabolic pathways and potentially having implications for biotechnological applications related to lipase-based processes [1,2,3].

References:

1. Yang, Wenjuan, Cao, Hai, Xu, Li, Zhang, Houjin, Yan, Yunjun. 2015. A novel eurythermic and thermostale lipase LipM from Pseudomonas moraviensis M9 and its application in the partial hydrolysis of algal oil. In BMC biotechnology, 15, 94. doi:10.1186/s12896-015-0214-0. https://pubmed.ncbi.nlm.nih.gov/26463643/

2. Martin, Natalia, Christensen, Quin H, Mansilla, María C, Cronan, John E, de Mendoza, Diego. 2011. A novel two-gene requirement for the octanoyltransfer reaction of Bacillus subtilis lipoic acid biosynthesis. In Molecular microbiology, 80, 335-49. doi:10.1111/j.1365-2958.2011.07597.x. https://pubmed.ncbi.nlm.nih.gov/21338420/

3. Christensen, Quin H, Cronan, John E. 2010. Lipoic acid synthesis: a new family of octanoyltransferases generally annotated as lipoate protein ligases. In Biochemistry, 49, 10024-36. doi:10.1021/bi101215f. https://pubmed.ncbi.nlm.nih.gov/20882995/