Publications

• Menaquinone biosynthesis: formation of aminofutalosine requires a unique radical SAM enzyme.

  Mahanta N., Fedoseyenko D., Dairi T., Begley T.P.

  Menaquinone (MK, vitamin K2) is a lipid-soluble molecule that participates in the bacterial electron transport chain. In mammalian cells, MK functions as an essential vitamin for the activation of various proteins involved in blood clotting and bone metabolism. Recently, a new pathway for the bios ... >> More

  Menaquinone (MK, vitamin K2) is a lipid-soluble molecule that participates in the bacterial electron transport chain. In mammalian cells, MK functions as an essential vitamin for the activation of various proteins involved in blood clotting and bone metabolism. Recently, a new pathway for the biosynthesis of this cofactor was discovered in Streptomyces coelicolor A3(2) in which chorismate is converted to aminofutalosine in a reaction catalyzed by MqnA and an unidentified enzyme. Here, we reconstitute the biosynthesis of aminofutalosine and demonstrate that the missing enzyme (aminofutalosine synthase, MqnE) is a radical SAM enzyme that catalyzes the addition of the adenosyl radical to the double bond of 3-[(1-carboxyvinyl)oxy]benzoic acid. This is a new reaction type in the radical SAM superfamily. << Less

  J. Am. Chem. Soc. 135:15318-15321(2013) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• An alternative menaquinone biosynthetic pathway operating in microorganisms.

  Hiratsuka T., Furihata K., Ishikawa J., Yamashita H., Itoh N., Seto H., Dairi T.

  In microorganisms, menaquinone is an obligatory component of the electron-transfer pathway. It is derived from chorismate by seven enzymes in Escherichia coli. However, a bioinformatic analysis of whole genome sequences has suggested that some microorganisms, including pathogenic species such as H ... >> More

  In microorganisms, menaquinone is an obligatory component of the electron-transfer pathway. It is derived from chorismate by seven enzymes in Escherichia coli. However, a bioinformatic analysis of whole genome sequences has suggested that some microorganisms, including pathogenic species such as Helicobacter pylori and Campylobacter jejuni, do not have orthologs of the men genes, even though they synthesize menaquinone. We deduced the outline of this alternative pathway in a nonpathogenic strain of Streptomyces by bioinformatic screening, gene knockouts, shotgun cloning with isolated mutants, and in vitro studies with recombinant enzymes. As humans and commensal intestinal bacteria, including lactobacilli, lack this pathway, it represents an attractive target for the development of chemotherapeutics. << Less

  Science 321:1670-1673(2008) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• 5'-methylthioadenosine nucleosidase is implicated in playing a key role in a modified futalosine pathway for menaquinone biosynthesis in Campylobacter jejuni.

  Li X., Apel D., Gaynor E.C., Tanner M.E.

  Menaquinone (vitamin K(2)) serves as an electron carrier in the electron transport chain required for respiration in many pathogenic bacteria. Most bacteria utilize a common menaquinone biosynthetic pathway as exemplified by Escherichia coli. Recently, a novel biosynthetic pathway, the futalosine ... >> More

  Menaquinone (vitamin K(2)) serves as an electron carrier in the electron transport chain required for respiration in many pathogenic bacteria. Most bacteria utilize a common menaquinone biosynthetic pathway as exemplified by Escherichia coli. Recently, a novel biosynthetic pathway, the futalosine pathway, was discovered in Streptomyces. Bioinformatic analysis strongly suggests that this pathway is also operative in the human pathogens Campylobacter jejuni and Helicobacter pylori. Here, we provide compelling evidence that a modified futalosine pathway is operative in C. jejuni and that it utilizes 6-amino-6-deoxyfutalosine instead of futalosine. A key step in the Streptomyces pathway involves a nucleosidase called futalosine hydrolase. The closest homolog in C. jejuni has been annotated as a 5'-methylthioadenosine nucleosidase (MTAN). We have shown that this C. jejuni enzyme has MTAN activity but negligible futalosine hydrolase activity. However, the C. jejuni MTAN is able to hydrolyze 6-amino-6-deoxyfutalosine at a rate comparable with that of its known substrates. This suggests that the adenine-containing version of futalosine is the true biosynthetic intermediate in this organism. To demonstrate this in vivo, we constructed a C. jejuni mutant strain deleted for mqnA2, which is predicted to encode for the enzyme required to synthesize 6-amino-6-deoxyfutalosine. Growth of this mutant was readily rescued by the addition of 6-amino-6-deoxyfutalosine, but not futalosine. This provides the first direct evidence that a modified futalosine pathway is operative in C. jejuni. It also highlights the tremendous versatility of the C. jejuni MTAN, which plays key roles in S-adenosylmethionine recycling, the biosynthesis of autoinducer molecules, and the biosynthesis of menaquinone. << Less

  J. Biol. Chem. 286:19392-19398(2011) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• Diversity of the early step of the futalosine pathway.

  Arakawa C., Kuratsu M., Furihata K., Hiratsuka T., Itoh N., Seto H., Dairi T.

  We recently demonstrated that the futalosine pathway was operating in some bacteria for the biosynthesis of menaquinone and that futalosine was converted into dehypoxanthinyl futalosine (DHFL) by an MqnB of Thermus thermophilus. In this study, we found that aminodeoxyfutalosine, which has adenine ... >> More

  We recently demonstrated that the futalosine pathway was operating in some bacteria for the biosynthesis of menaquinone and that futalosine was converted into dehypoxanthinyl futalosine (DHFL) by an MqnB of Thermus thermophilus. In this study, we found that aminodeoxyfutalosine, which has adenine instead of hypoxanthine in futalosine, was directly converted into DHFL by an MqnB of Helicobacter pylori. Therefore, this step is potentially an attractive target for the development of specific anti-H. pylori drugs. << Less

  Antimicrob. Agents Chemother. 55:913-916(2011) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.