Publications

• Biotin synthase mechanism: an overview.

  Lotierzo M., Tse Sum Bui B., Florentin D., Escalettes F., Marquet A.

  Biotin synthase, a member of the 'radical SAM' (S-adenosylmethionine) family, converts DTB (dethiobiotin) into biotin. The active form of the Escherichia coli enzyme contains two (Fe-S) centres, a (4Fe-4S) and a (2Fe-2S). The (4Fe-4S)2+/+ mediates the electron transfer required for the reductive c ... >> More

  Biotin synthase, a member of the 'radical SAM' (S-adenosylmethionine) family, converts DTB (dethiobiotin) into biotin. The active form of the Escherichia coli enzyme contains two (Fe-S) centres, a (4Fe-4S) and a (2Fe-2S). The (4Fe-4S)2+/+ mediates the electron transfer required for the reductive cleavage of SAM into methionine and a DOA* (deoxyadenosyl radical). Two DOA*, i.e. two SAM molecules, are consumed to activate the positions 6 and 9 of DTB. A direct transfer of isotope from the labelled substrate into DOAH (deoxyadenosine) has been observed with 2H, although not quantitatively, but not with tritium. The source of the sulphur introduced to form biotin is still under debate. We have shown that the (2Fe-2S)2+ cluster can be reconstituted in the apoenzyme with S2- and Fe2+. When S2-was replaced by [34S2-], [35S2-] or Se2-, biotin containing mostly the sulphur isotopes or selenium was obtained. This leads us to favour the hypothesis that the (2Fe-2S) centre is the sulphur donor, which may explain the absence of turnover of the enzyme. DTBSH (9-mercaptodethiobiotin), which already contains the sulphur atom of biotin, was shown to be an alternative substrate of biotin synthase both in vivo and with a crude extract. When this compound was tested with a well-defined in vitro system, the same turnover of one and similar reaction rates were observed for DTB and DTBSH. We postulate that the same intermediate is formed from both substrates. << Less

  Biochem Soc Trans 33:820-823(2005) [PubMed] [EuropePMC]

• The gene for biotin synthase from Saccharomyces cerevisiae: cloning, sequencing, and complementation of Escherichia coli strains lacking biotin synthase.

  Zhang S., Sanyal I., Bulboaca G.H., Rich A., Flint D.H.

  Biotin synthase catalyzes the insertion of a sulfur atom between two carbon atoms of dethiobiotin to form biotin in the last step of the biotin biosynthesis pathway. In Escherichia coli, biotin synthase is coded for by bioB gene. We report here cloning, sequencing, and initial functional character ... >> More

  Biotin synthase catalyzes the insertion of a sulfur atom between two carbon atoms of dethiobiotin to form biotin in the last step of the biotin biosynthesis pathway. In Escherichia coli, biotin synthase is coded for by bioB gene. We report here cloning, sequencing, and initial functional characterization of the yeast gene for biotin synthase in Saccharomyces cerevisiae. We have named this gene BIO2. It consists of a 355-codon open reading frame near the ZUO1 gene. Analysis of the yeast protein encoded by the BIO2 gene reveals that it shares extensive homology with biotin synthases of E. coli and Bacillus sphaericus. The yeast and the two bacterial biotin synthase proteins have similar molecular weights, amino acid compositions, and hydropathies. The plasmid pUCBIO2 containing the yeast BIO2 gene completely complements E. coli bioB- and delta bio mutants and enables these mutants to grow on dethiobiotin. Although BIO2 is physically linked to ZUO1, which encodes the putative left-handed Z-DNA binding protein zuotin, it appears to be regulated independently from it. The yeast BIO2 and ZUO1 genes reside near ADE3 gene on chromosome VII. BIO2 is the first eukaryotic gene reported from the biotin biosynthetic pathway. << Less

  Arch. Biochem. Biophys. 309:29-35(1994) [PubMed] [EuropePMC]

• Transcriptional regulation and gene arrangement of Escherichia coli, Citrobacter freundii and Salmonella typhimurium biotin operons.

  Shiuan D., Campbell A.

  The bio operons of Citrobacter freundii and Escherichia coli K-12 (strain C600) were isolated by screening lambda banks for complementation of E. coli bio mutants. These were compared with the previously isolated bio operon of Salmonella typhimurium and previous data on E. coli K-12. The restricti ... >> More

  The bio operons of Citrobacter freundii and Escherichia coli K-12 (strain C600) were isolated by screening lambda banks for complementation of E. coli bio mutants. These were compared with the previously isolated bio operon of Salmonella typhimurium and previous data on E. coli K-12. The restriction maps of the operon are very different in the three species, but no difference in gene order was found. Operator-promoter DNA, identified by repressible titration and by biotin-repressible transcription in E. coli, was sequenced and compared to the published E. coli K-12 sequence. In the segment previously identified as operator/bioB promoter, C. freundii and S. typhimurium DNA are identical and differ from E. coli only by 2 bp. The DNA to the right of this segment (indicated by previous data to be the bioA promoter of E. coli) has diverged in all three species, and only E. coli has a sequence resembling a consensus promoter. << Less

  Gene 67:203-211(1988) [PubMed] [EuropePMC]

• Crystal structure of biotin synthase, an S-adenosylmethionine-dependent radical enzyme.

  Berkovitch F., Nicolet Y., Wan J.T., Jarrett J.T., Drennan C.L.

  The crystal structure of biotin synthase from Escherichia coli in complex with S-adenosyl-L-methionine and dethiobiotin has been determined to 3.4 angstrom resolution. This structure addresses how "AdoMet radical" or "radical SAM" enzymes use Fe4S4 clusters and S-adenosyl-L-methionine to generate ... >> More

  The crystal structure of biotin synthase from Escherichia coli in complex with S-adenosyl-L-methionine and dethiobiotin has been determined to 3.4 angstrom resolution. This structure addresses how "AdoMet radical" or "radical SAM" enzymes use Fe4S4 clusters and S-adenosyl-L-methionine to generate organic radicals. Biotin synthase catalyzes the radical-mediated insertion of sulfur into dethiobiotin to form biotin. The structure places the substrates between the Fe4S4 cluster, essential for radical generation, and the Fe2S2 cluster, postulated to be the source of sulfur, with both clusters in unprecedented coordination environments. << Less

  Science 303:76-79(2004) [PubMed] [EuropePMC]