Download MendeleyStructural Insights into the Mechanism of a Polyketide Synthase Thiocysteine Lyase Domain.
Steele, A.D., Meng, S., Li, G., Kalkreuter, E., Chang, C., Shen, B.(2024) J Am Chem Soc 146: 32605-32617
- PubMed: 39546807 Search on PubMed
- DOI: https://doi.org/10.1021/jacs.4c11656
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9CEN - PubMed Abstract:
Polyketide synthases (PKSs) are renowned for the structural diversity of the polyketide natural products they produce, but sulfur-containing functionalities are rarely installed by PKSs. We previously characterized thiocysteine lyase (SH) domains involved in the biosynthesis of the leinamycin (LNM) family of natural products, exemplified by LnmJ-SH and guangnanmycin (GnmT-SH). Here we report a detailed investigation into the PLP-dependent reaction catalyzed by the SH domains, guided by a 1.8 Å resolution crystal structure of GnmT-SH. A series of elaborate substrate mimics were synthesized to answer specific questions garnered from the crystal structure and from the biosynthetic logic of the LNM family of natural products. Through a combination of bioinformatics, molecular modeling, in vitro assays, and mutagenesis, we have developed a detailed model of acyl carrier protein (ACP)-tethered substrate-SH, and interdomain interactions, that contribute to the observed substrate specificity. Comparison of the GnmT-SH structure with archetypical PLP-dependent enzyme structures revealed how Nature, via evolution, has modified a common protein structural motif to accommodate an ACP-tethered substrate, which is significantly larger than any of those previously characterized. Overall, this study demonstrates how PLP-dependent chemistry can be incorporated into the context of PKS assembly lines and sets the stage for engineering PKSs to produce sulfur-containing polyketides.
- Department of Chemistry, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, Florida 33458, United States.
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