The Schmeing Lab

Visualizing and understanding nature’s biosynthetic macromolecular machines

Large NRPS proteins

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In their assembly-line logic and complicated catalytic cycle, NRPS domains and modules must work in concert to synthesize the nonribosomal peptide product. To investigate the holistic workings of NRPSs, we use X-ray crystallography, chemical biology tools, biophysical techniques and biochemical methods to elucidate their structures and functions. Good examples of these studies include our solving of four independent structures of the initiation module of the NRPS that synthesizes the clinically important antibiotic gramicidin. It provides fundamental insight into the initial stages of gramicidin synthesis, including the crucial formylation event, and into nonribosomal synthesis in general. The movements required for synthesis are staggering, with both the PCP domain translocating 61 Å and rotating 75° and the A subdomain rotating 180° in just one of these required transitions, to transport substrate between two distal active sites. The structures also highlight the great versatility of NRPSs, as small domains repurpose and recycle their limited interfaces to interact with their various binding partners.
We combined electron microscopy and X-ray crystallography to get even wider views of NRPSs in action. Our recent EM studies on a dimodular bacillibactin synthetase protein produced the first 3D views of a multi-modular NRPS. Accompanying pan-module X-ray structures begin to show the higher-order architectural features NRPSs require for to perform their syntheses. Further studies of large NRPSs by EM and X-ray crystallography are a major initiative in the lab.

Relevant Schmeing lab papers: Fortinez et al, Nature Comm 2022; Reimer et al, Science 2019; Reimer et al, Curr Opin in Struct Biol. 2018; Tarry et al, Structure, 2017; Reimer et al, Nature, 2016; Reimer et al, Acta D, 2016; Tarry et al, PEDS, 2015.