The BioC O-Methyltransferase Catalyzes Methyl Esterification of Malonyl-Acyl Carrier Protein, an Essential Step in Biotin Synthesis

Lin, Steven; Cronan, John E.

doi:10.1074/jbc.m112.410290

Cited by 58 publications

(62 citation statements)

References 33 publications

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“…The BioCs of close relatives of E. coli were as intractable as E. coli BioC and thus the BioCs of more diverse bacteria were tested. Expression of the BioC of Bacillus cereus in E. coli restored biotin synthesis to an E. coli ΔbioC strain and this monomeric protein could be expressed in soluble form in E. coli and purified to homogeneity (32). In disagreement with prior scenarios that favored malonyl-CoA as the methyl acceptor, malonyl-ACP was a far better acceptor of methyl groups from S-adenosyl- l -methionine than was malonyl-CoA.…”

Section: The Pathway and Proteins Of Biotin Synthesismentioning

confidence: 99%

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Biotin and Lipoic Acid: Synthesis, Attachment, and Regulation

Cronan

2014

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Summary Two vitamins, biotin and lipoic acid, are essential in all three domains of life. Both coenzymes function only when covalently attached to key metabolic enzymes. There they act as “swinging arms” that shuttle intermediates between two active sites (= covalent substrate channeling) of key metabolic enzymes. Although biotin was discovered over 100 years ago and lipoic acid 60 years ago, it was not known how either coenzyme is made until recently. In Escherichia coli the synthetic pathways for both coenzymes have now been worked out for the first time. The late steps of biotin synthesis, those involved in assembling the fused rings, were well-described biochemically years ago, although recent progress has been made on the BioB reaction, the last step of the pathway in which the biotin sulfur moiety is inserted. In contrast, the early steps of biotin synthesis, assembly of the fatty acid-like “arm” of biotin were unknown. It has now been demonstrated that the arm is made by using disguised substrates to gain entry into the fatty acid synthesis pathway followed by removal of the disguise when the proper chain length is attained. The BioC methyltransferase is responsible for introducing the disguise and the BioH esterase for its removal. In contrast to biotin, which is attached to its cognate proteins as a finished molecule, lipoic acid is assembled on its cognate proteins. An octanoyl moiety is transferred from the octanoyl-ACP of fatty acid synthesis to a specific lysine residue of a cognate protein by the LipB octanoyl transferase followed by sulfur insertion at carbons C6 and C8 by the LipA lipoyl synthetase. Assembly on the cognate proteins regulates the amount of lipoic acid synthesized and thus there is no transcriptional control of the synthetic genes. In contrast transcriptional control of the biotin synthetic genes is wielded by a remarkably sophisticated, yet simple, system, exerted through BirA a dual function protein that both represses biotin operon transcription and ligates biotin to its cognate protein.

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Section: The Pathway and Proteins Of Biotin Synthesismentioning

confidence: 99%

“…However, if BioC is overly active, it would convert too much malonyl-ACP to the methylated species and thereby block fatty acid synthesis. Indeed, BioC overproduction provides a very effective means to block E. coli fatty acid synthesis (32). …”

Section: The Pathway and Proteins Of Biotin Synthesismentioning

confidence: 99%

Biotin and Lipoic Acid: Synthesis, Attachment, and Regulation

Cronan

2014

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“…It was found that the role of BioC is to facilitate biotin synthesis by deceiving fatty acid synthesis into making the pimelate moiety. BioC methylates the free carboxyl of a small portion of the key fatty acid precursor, malonyl‐ACP (Lin and Cronan, ). Methylation eliminates the charge of the free carboxyl of malonyl‐ACP and the resulting malonyl‐ACP methyl ester is able to access the hydrophobic active site usually occupied by an acetyl‐thioester.…”

Section: Introductionmentioning

confidence: 99%

Pimelic acid, the first precursor of the Bacillus subtilis biotin synthesis pathway, exists as the free acid and is assembled by fatty acid synthesis

Manandhar

Cronan

2017

Molecular Microbiology

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Summary Biotin synthetic pathways are readily separated into two stages, synthesis of the seven carbon α, ω-dicarboxylic acid pimelate moiety and assembly of the fused heterocyclic rings. The biotin pathway genes responsible for pimelate moiety synthesis vary widely among bacteria whereas the ring synthesis genes are highly conserved. Bacillus subtilis seems to have redundant genes, bioI and bioW, for generation of the pimelate intermediate. Largely consistent with previous genetic studies we found that deletion of bioW caused a biotin auxotrophic phenotype whereas deletion of bioI did not. BioW is a pimeloyl-CoA synthetase that converts pimelic acid to pimeloyl-CoA. The essentiality of BioW for biotin synthesis indicates that the free form of pimelic acid is an intermediate in biotin synthesis although this is not the case in E. coli. Since the origin of pimelic acid in Bacillus subtilis is unknown, we carried out 13C-NMR studies to decipher the pathway for its generation. Our data provided evidence for the role of free pimelate in biotin synthesis and the involvement of fatty acid synthesis in pimelate production. Cerulenin, an inhibitor of the key fatty acid elongation enzyme, FabF, markedly decreased biotin production by B. subtilis resting cells whereas a strain having a cerulenin-resistant FabF mutant produced more biotin. In addition, supplementation with pimelic acid fully restored biotin production in cerulenin-treated cells. These results indicate that pimelic acid originating from fatty acid synthesis pathway is a bona fide precursor of biotin in B. subtilis.

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“…Recently, we found that the generation of pimeloyl moiety in earlier steps of biotin synthesis is involved in a modified type II fatty acid biosynthetic pathway in E. coli (6)(7)(8). In the BioC-BioH pathway of pimelate synthesis, BioC methylates malonyl coenzyme A (malonyl-CoA; or ACP) and gives a methyl malonyl-thioester destined to fatty acid biosynthesis to act as a primer (6,7,9), whereas the bioH gene product demethylates the pimeloyl-ACP methyl ester to form pimeloyl-ACP after two rounds of the fatty acid elongation cycle (6,7,10). The subsequent four-step pathway functions in assembling the double rings of the biotin molecule (6-8) (Fig.…”

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Brucella BioR Regulator Defines a Complex Regulatory Mechanism for Bacterial Biotin Metabolism

Feng

Zhang

et al. 2013

J Bacteriol

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eThe enzyme cofactor biotin (vitamin H or B7) is an energetically expensive molecule whose de novo biosynthesis requires 20 ATP equivalents. It seems quite likely that diverse mechanisms have evolved to tightly regulate its biosynthesis. Unlike the model regulator BirA, a bifunctional biotin protein ligase with the capability of repressing the biotin biosynthetic pathway, BioR has been recently reported by us as an alternative machinery and a new type of GntR family transcriptional factor that can repress the expression of the bioBFDAZ operon in the plant pathogen Agrobacterium tumefaciens. However, quite unusually, a closely related human pathogen, Brucella melitensis, has four putative BioR-binding sites (both bioR and bioY possess one site in the promoter region, whereas the bioBFDAZ [bio] operon contains two tandem BioR boxes). This raised the question of whether BioR mediates the complex regulatory network of biotin metabolism. Here, we report that this is the case. The B. melitensis BioR ortholog was overexpressed and purified to homogeneity, and its solution structure was found to be dimeric. Functional complementation in a bioR isogenic mutant of A. tumefaciens elucidated that Brucella BioR is a functional repressor. Electrophoretic mobility shift assays demonstrated that the four predicted BioR sites of Brucella plus the BioR site of A. tumefaciens can all interact with the Brucella BioR protein. In a reporter strain that we developed on the basis of a double mutant of A. tumefaciens (the ⌬bioR ⌬bioBFDA mutant), the ␤-galactosidase (␤-Gal) activity of three plasmid-borne transcriptional fusions (bioBbme-lacZ, bioYbme-lacZ, and bioRbme-lacZ) was dramatically decreased upon overexpression of Brucella bioR. Real-time quantitative PCR analyses showed that the expression of bioBFDA and bioY is significantly elevated upon removal of bioR from B. melitensis. Together, we conclude that Brucella BioR is not only a negative autoregulator but also a repressor of expression of bioY and bio operons that separately function in biotin transport and the biosynthesis pathway.

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The BioC O-Methyltransferase Catalyzes Methyl Esterification of Malonyl-Acyl Carrier Protein, an Essential Step in Biotin Synthesis

Cited by 58 publications

References 33 publications

Biotin and Lipoic Acid: Synthesis, Attachment, and Regulation

Biotin and Lipoic Acid: Synthesis, Attachment, and Regulation

Pimelic acid, the first precursor of the Bacillus subtilis biotin synthesis pathway, exists as the free acid and is assembled by fatty acid synthesis

Brucella BioR Regulator Defines a Complex Regulatory Mechanism for Bacterial Biotin Metabolism

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