Non-ribosomal peptide synthetases
Andrew Gulick group (Hauptman-Woodward Institute)
The laboratory of Andrew Gulick determined structures
of two nonribosomal peptide synthetase (NRPS) enzymes. The large,
multidomain NRPSs use an assembly-line strategy to produce bio-active
peptides including antibiotics such as vancomycin and teichobactin,
anticancer agents like bleomycin, and siderophores such as mycobactin
and pyoverdine, which are important virulence determinants. During
synthesis, the amino-acid substrates and nascent peptide are covalently
attached to peptidyl carrier protein (PCP) domains that are integrated
within the multi-domain NRPS protein. Large conformational changes are
therefore required for the PCP to reach the neighboring catalytic
domains. The new structures illustrate the conformation of NRPS
proteins in distinct states of the catalytic cycle. One structure shows
the PCP domain bound within the adenylation domain where it is
positioned for amino acid loading. This structure exploited a
mechanism-based inhibitor conceived and synthesized by collaborator
Courtney Aldrich (University of Minnesota). The second structure
illustrates the PCP domain bound to the condensation domain, poised to
accept the upstream peptide. The two structures demonstrate that a 140°
sub-domain rotation within the adenylation domain is used to transport
the PCP between the catalytic domains. The dynamics of NRPS proteins
was further supported by single particle electron microscopy (EM) from
Georgios Skiniotis (University of Michigan). The structures should
facilitate engineering NRPS catalysts to produce novel peptide
therapeutics.
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Figure: Two multi-domain NRPS
proteins. The left panel shows the PCP (cyan) bound within the
condensation domain (white). Rotation of the small C-terminal subdomain
(orange) of the adenylation domain (yellow) transports the PCP to the
adenylation domain active site in the structure on the right.
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Citation: Drake, E.J., Miller, B.R., Shi, C.,
Tarrasch, J.T., Sundlov, J.A., Allen, C.L., Skiniotis, G., Aldrich,
C.C., and Gulick, A.M. (2016) Structures of two distinct
conformations of holo-non-ribosomal peptide synthetases.
Nature 529, 235-238.
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