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Structural characterization of four prochlorosins: a novel class of lantipeptides produced by planktonic marine cyanobacteria.

Tang W, van der Donk WA - Biochemistry (2012)

Bottom Line: These polycyclic peptides contain lanthionine and methyllanthionine residues that result in thioether cross-links.All methyllanthionines had the (2S,3S,6R) configuration, and the lanthionines had the (2S,6R) configuration, irrespective of the direction of cyclization, ring size, or ring topology.These findings indicate that most, if not all, of the rings in prochlorosins are formed enzymatically by ProcM lanthionine synthetase and not by a nonenzymatic process as previously suggested.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

ABSTRACT
Prochlorosins make up a class of secondary metabolites produced by strains of Prochlorococcus, single-cell, planktonic marine cyanobacteria. These polycyclic peptides contain lanthionine and methyllanthionine residues that result in thioether cross-links. In Prochlorococcus MIT9313, a single enzyme, ProcM, catalyzes the posttranslational modification of 29 linear peptide substrates to generate a library of highly diverse cyclic peptides. To investigate the catalytic promiscuity of ProcM, we chose four prochlorosins previously demonstrated to be produced by the organism for detailed structural characterization. Nuclear magnetic resonance studies allowed unambiguous assignment of the ring topologies, demonstrating a high degree of topological diversity. The stereochemistry of the lanthionine and methyllanthionine residues was determined by gas chromatography and mass spectrometry for seven prochlorosins. All methyllanthionines had the (2S,3S,6R) configuration, and the lanthionines had the (2S,6R) configuration, irrespective of the direction of cyclization, ring size, or ring topology. These findings indicate that most, if not all, of the rings in prochlorosins are formed enzymatically by ProcM lanthionine synthetase and not by a nonenzymatic process as previously suggested.

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Ring topology of fourselectedprochlorosins assigned by NMR spectroscopy in this work. Arrows indicatethe start of the putative core peptide. Asterisks indicate prochlorosinscontaining five more residues at their N-terminus that originate fromthe leader peptides. Blue residues are the engineered cleavage sitesat position −1 in the leader peptides.
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fig4: Ring topology of fourselectedprochlorosins assigned by NMR spectroscopy in this work. Arrows indicatethe start of the putative core peptide. Asterisks indicate prochlorosinscontaining five more residues at their N-terminus that originate fromthe leader peptides. Blue residues are the engineered cleavage sitesat position −1 in the leader peptides.

Mentions: Illustration of the method used to establish thioetherconnectivities.(A) Schematic illustration of the proton correlations used to determinering topologies. (B) Section of the NOESY spectrum (mixing time of0.40 s) of Pcn1.7 in D2O showing the correlations betweenβ protons. (C) Section of the NOESY spectrum showing the correlationsof the α protons with α and β protons across thethioether bridge. (D) Section of the NOESY spectrum showing the correlationsof the γ protons with α and β protons across thethioether bridge. In panels B–D, correlations are assignedto rings A, B, and C of Pcn1.7 (see also Figure 4). For enlarged panels B and C, see Figures S18 and S19 of the Supporting Information.


Structural characterization of four prochlorosins: a novel class of lantipeptides produced by planktonic marine cyanobacteria.

Tang W, van der Donk WA - Biochemistry (2012)

Ring topology of fourselectedprochlorosins assigned by NMR spectroscopy in this work. Arrows indicatethe start of the putative core peptide. Asterisks indicate prochlorosinscontaining five more residues at their N-terminus that originate fromthe leader peptides. Blue residues are the engineered cleavage sitesat position −1 in the leader peptides.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3361976&req=5

fig4: Ring topology of fourselectedprochlorosins assigned by NMR spectroscopy in this work. Arrows indicatethe start of the putative core peptide. Asterisks indicate prochlorosinscontaining five more residues at their N-terminus that originate fromthe leader peptides. Blue residues are the engineered cleavage sitesat position −1 in the leader peptides.
Mentions: Illustration of the method used to establish thioetherconnectivities.(A) Schematic illustration of the proton correlations used to determinering topologies. (B) Section of the NOESY spectrum (mixing time of0.40 s) of Pcn1.7 in D2O showing the correlations betweenβ protons. (C) Section of the NOESY spectrum showing the correlationsof the α protons with α and β protons across thethioether bridge. (D) Section of the NOESY spectrum showing the correlationsof the γ protons with α and β protons across thethioether bridge. In panels B–D, correlations are assignedto rings A, B, and C of Pcn1.7 (see also Figure 4). For enlarged panels B and C, see Figures S18 and S19 of the Supporting Information.

Bottom Line: These polycyclic peptides contain lanthionine and methyllanthionine residues that result in thioether cross-links.All methyllanthionines had the (2S,3S,6R) configuration, and the lanthionines had the (2S,6R) configuration, irrespective of the direction of cyclization, ring size, or ring topology.These findings indicate that most, if not all, of the rings in prochlorosins are formed enzymatically by ProcM lanthionine synthetase and not by a nonenzymatic process as previously suggested.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

ABSTRACT
Prochlorosins make up a class of secondary metabolites produced by strains of Prochlorococcus, single-cell, planktonic marine cyanobacteria. These polycyclic peptides contain lanthionine and methyllanthionine residues that result in thioether cross-links. In Prochlorococcus MIT9313, a single enzyme, ProcM, catalyzes the posttranslational modification of 29 linear peptide substrates to generate a library of highly diverse cyclic peptides. To investigate the catalytic promiscuity of ProcM, we chose four prochlorosins previously demonstrated to be produced by the organism for detailed structural characterization. Nuclear magnetic resonance studies allowed unambiguous assignment of the ring topologies, demonstrating a high degree of topological diversity. The stereochemistry of the lanthionine and methyllanthionine residues was determined by gas chromatography and mass spectrometry for seven prochlorosins. All methyllanthionines had the (2S,3S,6R) configuration, and the lanthionines had the (2S,6R) configuration, irrespective of the direction of cyclization, ring size, or ring topology. These findings indicate that most, if not all, of the rings in prochlorosins are formed enzymatically by ProcM lanthionine synthetase and not by a nonenzymatic process as previously suggested.

Show MeSH