Abstract 2295 Menaquinone Biosynthesis: Regioselectivity of Prenylation and Methylation in the final steps of aminofutalosine pathway

Menaquinone is a vital redox cofactor in bacteria, and its biosynthesis has been reported to occur by two different routes. The more recently discovered aminofutalosine pathway is found in pathogenic bacteria like H. pylori, making it an attractive target for antibacterial drugs. The biosynthesis of menaquinone from 5,8-dihydroxy-2-naphthoic acid in the aminofutalosine pathway is proposed to involve four enzymes that tailor the naphthaquinone core. One of the enzymes involved, MqnP, is an integral-membrane prenyltransferase that attaches the poly-prenyl tail to menaquinone, while MqnG is a membrane-anchored methyltransferase. This study establishes an intrinsic regioselectivity of the prenylation and methylation. Then, the regioselectivity is investigated using isotope-labeled substrate feeding and NMR studies. Further, the regioselectivity exhibited by MqnP might justify the need for a separate decarboxylase enzyme MqnL in the aminofutalosine pathway. The elucidation of the prenyltransferase product sets the stage for studying the UbiD-like decarboxylase involved in menaquinone biosynthesis. Also, the possible sequence of tailoring enzymes has been narrowed down by studying MqnG and MqnP-mediated reactions. The complete elucidation of the aminofutalosine pathway allows a better understanding of the parallels and differences from the OSB pathway. This study utilizes partial reconstitution of MqnG and in vivo analysis of the MqnP reaction to clarify the role of the tailoring enzymes. Future investigations on the decarboxylase units MqnM-MqnL will complete our knowledge of the aminofutalosine pathway. NSF grant proposal ID #2204203