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A transglutaminase homologue as a condensation catalyst in antibiotic assembly lines


The unrelenting emergence of antibiotic-resistant bacterial pathogens demands the investigation of antibiotics with new modes of action. The pseudopeptide antibiotic andrimid is a nanomolar inhibitor of the bacterial acetyl-CoA carboxylase that catalyses the first committed step in prokaryotic fatty acid biosynthesis1. Recently, the andrimid (adm) biosynthetic gene cluster was isolated and heterologously expressed in Escherichia coli2. This establishes a heterologous biological host in which to rapidly probe features of andrimid formation and to use biosynthetic engineering to make unnatural variants of this important and promising new class of antibiotics. Bioinformatic analysis of the adm cluster revealed a dissociated biosynthetic assembly system lacking canonical amide synthases between the first three carrier protein domains. Here we report that AdmF, a transglutaminase (TGase) homologue, catalyses the formation of the first amide bond, an N-acyl-β-peptide link, in andrimid biosynthesis. Hence, AdmF is a newly discovered biosynthetic enzyme that acts as a stand-alone amide synthase between protein-bound, thiotemplated substrates in an antibiotic enzymatic assembly line. TGases (enzyme class (EC) normally catalyse the cross-linking of (poly)peptides by creating isopeptidic bonds between the γ-carboxamide group of a glutamine side chain of one protein and various amine donors, including lysine side chains3. To the best of our knowledge, the present study constitutes the first report of a TGase-like enzyme recruited for the assembly of an antibiotic. Moreover, genome mining using the AdmF sequence yielded additional TGases in unassigned natural product biosynthetic pathways. With many more microbial genomes being sequenced, such a strategy could potentially unearth biosynthetic pathways producing new classes of antibiotics.

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Figure 1: First condensation step in andrimid biosynthesis.
Figure 2: Analysis of the AdmF-catalysed condensation of octatrienoyl to β-phenylalanine.
Figure 3: Proposed mechanism of AdmF compared with prototypical ketosynthase (KS) domains in PKS and condensation (C) domains in NRPS.


  1. 1

    Freiberg, C. et al. Identification and characterization of the first class of potent bacterial acetyl-CoA carboxylase inhibitors with antibacterial activity. J. Biol. Chem. 279, 26066–26073 (2004)

    CAS  Article  Google Scholar 

  2. 2

    Jin, M., Fischbach, M. A. & Clardy, J. A biosynthetic gene cluster for the acetyl-CoA carboxylase inhibitor andrimid. J. Am. Chem. Soc. 128, 10660–10661 (2006)

    CAS  Article  Google Scholar 

  3. 3

    Walsh, C. T. Posttranslational modification of proteins, expanding nature's inventory (Roberts and Company Publishers, Englewood, Colorado, 2006)

    Google Scholar 

  4. 4

    Needham, J., Kelly, M. T., Ishige, M. & Andersen, R. J. Andrimid and moiramides a–c, metabolites produced in culture by a marine isolate of the bacterium Pseudomonas fluorescens: Structure elucidation and biosynthesis. J. Org. Chem. 59, 2058–2063 (1994)

    CAS  Article  Google Scholar 

  5. 5

    Oclarit, J. M. et al. Anti-Bacillus substance in the marine sponge, Hyatella species, produced by an associated Vibrio species bacterium. Microbios 78, 7–16 (1994)

    CAS  PubMed  Google Scholar 

  6. 6

    Fredenhagen, A. et al. Andrimid, a new peptide antibiotic produced by an intracellular bacterial symbiont isolated from a brown planthopper. J. Am. Chem. Soc. 109, 4409–4411 (1987)

    CAS  Article  Google Scholar 

  7. 7

    Fischbach, M. A. & Walsh, C. T. Assembly-line enzymology for polyketide and nonribosomal peptide antibiotics: Logic, machinery, and mechanisms. Chem. Rev. 106, 3468–3496 (2006)

    CAS  Article  Google Scholar 

  8. 8

    Xiang, L., Moore, B. & Inactivation, S. Complementation, and heterologous expression of encP, a novel bacterial phenylalanine ammonia-lyase gene. J. Biol. Chem. 277, 32505–32509 (2002)

    CAS  Article  Google Scholar 

  9. 9

    Christenson, S. D., Wu, W., Spies, M. A., Shen, B. & Toney, M. D. Kinetic analysis of the 4-methylideneimidazole-5-one-containing tyrosine aminomutase in enediyne antitumor antibiotic C-1027 biosynthesis. Biochemistry 42, 12708–12718 (2003)

    CAS  Article  Google Scholar 

  10. 10

    Walker, K. D., Klettke, K., Akiyama, T. & Croteau, R. Cloning, heterologous expression, and characterization of a phenylalanine aminomutase involved in taxol biosynthesis. J. Biol. Chem. 279, 53947–53954 (2004)

    CAS  Article  Google Scholar 

  11. 11

    Yee, V. C. et al. Three-dimensional structure of a transglutaminase: Human blood coagulation factor XIII. Proc. Natl Acad. Sci. USA 91, 7296–7300 (1994)

    ADS  CAS  Article  Google Scholar 

  12. 12

    Keating, T. A. & Walsh, C. T. Initiation, elongation, and termination strategies in polyketide and polypeptide antibiotic biosynthesis. Curr. Opin. Chem. Biol. 3, 598–606 (1999)

    CAS  Article  Google Scholar 

  13. 13

    Liolios, K., Tavernarakis, N., Hugenholtz, P. & Kyrpides, N. C. The genomes on line database (gold) v.2: A monitor of genome projects worldwide. Nucleic Acids Res. 34, D332–D334 (2006)

    CAS  Article  Google Scholar 

  14. 14

    Datsenko, K. A. & Wanner, B. L. One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products. Proc. Natl Acad. Sci. USA 97, 6640–6645 (2000)

    ADS  CAS  Article  Google Scholar 

  15. 15

    Quadri, L. E. N. et al. Characterization of Sfp, a Bacillus subtilis phosphopantetheinyl transferase for peptidyl carrier protein domains in peptide synthetases. Biochemistry 37, 1585–1595 (1998)

    CAS  Article  Google Scholar 

  16. 16

    Staab, H. A., Lueking, M. & Duerr, F. H. The preparation of imidazolides. Synthesis of amides, hydrazides, and hydroxamic acids by the imidazolide method. Chem. Ber. 95, 1275–1283 (1962)

    CAS  Article  Google Scholar 

  17. 17

    Tonge, P. J. et al. Localized electron polarization in a substrate analog binding to the active site of enoyl-CoA hydratase: Raman spectroscopic and conformational analyses of rotamers of hexadienoyl thiolesters. Biospectroscopy 1, 387–394 (1995)

    CAS  Article  Google Scholar 

  18. 18

    Sampson, B. A., Misra, R. & Benson, S. A. Identification and characterization of a new gene of Escherichia coli K-12 involved in outer membrane permeability. Genetics 122, 491–501 (1989)

    CAS  PubMed  PubMed Central  Google Scholar 

  19. 19

    Molnar-Perl, I. Derivatization and chromatographic behavior of the o-phthaldialdehyde amino acid derivatives obtained with various SH-group-containing additives. J. Chromatogr. A. 913, 283–302 (2001)

    CAS  Article  Google Scholar 

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We thank J. Clardy for providing cosmid 2194C1 and M. Fischbach for helpful discussions. This work was supported in part by the NIH.

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Correspondence to Christopher T. Walsh.

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Reprints and permissions information is available at The authors declare no competing financial interests.

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Fortin, P., Walsh, C. & Magarvey, N. A transglutaminase homologue as a condensation catalyst in antibiotic assembly lines. Nature 448, 824–827 (2007).

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