Fueled by the explosion of (meta)genomic data, genome mining of specialized metabolites has become a major technology for drug discovery and studying microbiome ecology. In these efforts, computational tools like antiSMASH have played a central role through the analysis of Biosynthetic Gene Clusters (BGCs). Thousands of candidate BGCs from microbial genomes have been identified and stored in public databases. Interpreting the function and novelty of these predicted BGCs requires comparison with a well-documented set of BGCs of known function. The MIBiG (Minimum Information about a Biosynthetic Gene Cluster) Data Standard and Repository was established in 2015 to enable curation and storage of known BGCs. Here, we present MIBiG 2.0, which encompasses major updates to the schema, the data, and the online repository itself. Over the past five years, 851 new BGCs have been added. Additionally, we performed extensive manual data curation of all entries to improve the annotation quality of our repository. We also redesigned the data schema to ensure the compliance of future annotations. Finally, we improved the user experience by adding new features such as query searches and a statistics page, and enabled direct link-outs to chemical structure databases. The repository is accessible online at https://mibig.secondarymetabolites.org/.

The successful engineering of biosynthetic pathways hinges on understanding the factors that influence acyl carrier protein (ACP) stability and function. The stability and structure of ACPs can be influenced by the presence of divalent cations, but how this relates to primary sequence remains poorly understood. As part of a course-based undergraduate research experience, we investigated the thermostability of type II polyketide synthase (PKS) ACPs. We observed an approximate 40 °C range in the thermostability amongst the 14 ACPs studied, as well as an increase in stability (5 – 26 °C) of the ACPs in the presence of divalent cations. Distribution of charges in the helix II-loop-helix III region was found to impact the enthalpy of denaturation. Taken together, our results reveal clues as to how the sequence of type II PKS ACPs relates to their structural stability, information that can be used to study how ACP sequence relates to function.

Engineering biosynthetic pathways in microorganisms is a compelling route to gain access to novel molecules with drug‐like properties. Polyketide synthases (PKSs) utilize acyl carrier proteins (ACPs) to convert simple acetate building blocks into structurally complex molecules, many of which are antibiotics and anticancer agents. In a process known as combinatorial synthesis, biochemists have attempted to mix‐and‐match enzymes from different PKSs to create new hybrid synthases capable of synthesizing novel polyketide natural products. However, the ACP has proven to be a roadblock in these studies, as little is known about how the ACP functions and interacts with other enzymes due to its small and dynamic nature. To further our knowledge about the structure and function of ACPs, we cloned, expressed, and characterized a subset of 14 type II PKS ACPs. Temperature‐dependent circular dichroism (CD) experiments were conducted to determine the thermostability of the ACPs in the presence or absence of divalent cations. Our results indicate that despite strong sequence similarity, ACPs display a range in thermal stability. Further, the presence of metal ions confers additional stability to the ACP, presumably by decreasing electrostatic repulsive forces. Analytical ultracentrifugation‐sedimentation velocity experiments revealed that all ACPs sediment as monomers, and that despite sharing a common ancestor with fatty acid synthases, only one of the PKS ACPs studied interacted with the E. coli fatty acid ketosynthase, FabF.Support or Funding InformationWe would like to acknowledge an NSF CAREER Award #R15GM120704 and an NIH Award #CHE‐1652424 to Louise K. Charkoudian, as well as the Beckman Scholars Program, as sources of funding for this project.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.