Inefficient cellular delivery limits the landscape of macromolecular drugs. Boronic acids readily form boronate esters with the 1,2- and 1,3-diols of saccharides, such as those that coat the surface of mammalian cells. Here pendant boronic acids are shown to enhance the cytosolic delivery of a protein toxin. Thus, boronates are a noncationic carrier that can deliver a polar macromolecule into mammalian cells.

Artificial multienzyme scaffolds are being developed for in vitro cascaded biocatalytic activity and, in particular, accessing substrate channeling. This review covers progress in this field over the last ∼5 years with a specific focus on the scaffold materials themselves and the benefits they can provide for assembling multienzyme cascades in vitro. These benefits include improving biocatalytic efficiency, bypassing potential cellular toxicity, directed catalysis, modularity, incorporating enzymes from different prokaryotic and eukaryotic sources, and potentially the ability to create de novo designer cascades. We begin with an overview of the strongest impetus currently driving the rapid development of this field, namely, biomanufacturing and cell-free synthetic biology. We then discuss in detail pertinent mechanisms responsible for the benefits of artificial multienzyme scaffolds. In particular, we focus on substrate channeling, including the evolving debate about what leads to substrate channeling in artificial systems─proximity, confinement, or both─and whether sequential enzyme order is really needed. How different scaffold materials/chemistries can in turn affect enzyme activity is also discussed. The bulk of the review then details progress in the development of different biotic (e.g., cells) and abiotic (e.g., nanoparticles) scaffolding materials and is divided up by class and subtype as needed. Within each material class of scaffolds, attention is given to their inherent chemical diversity, how they are engineered, how they allow for enzymatic attachment, their ease of use, their benefits (e.g., inherent three-dimensional architecture) and liabilities where appropriate, and other relevant issues. For each scaffolding material, a detailed overview of current progress is provided using examples of multienzyme cascades and data/schematics reproduced from the literature. Special attention is also given to the use of DNA scaffolds, as they can potentially provide the most versatile designer three-dimensional scaffold architectures. Finally, a short perspective on how this rapidly moving field will evolve in the near and long terms is provided.

Drug resistant infectious diseases are quickly becoming a global health crisis. While Streptomyces spp. have been a major source of antibiotics over the past 50 years, efficient methods are needed to identify new antibiotics and greatly improve the rate of discovery. LCMS-based metabolomics were applied to analyze extracts of 50 Streptomyes spp. Using this methodology, we discovered bottromycin D and used whole genome sequencing to determine its biosynthesis by a ribosomal pathway.

A recent goal of synthetic biology has been to identify new chassis that provide benefits lacking in model organisms. Vibrio natriegens is a marine Gram-negative bacterium which is an emergent synthetic biology chassis with inherent benefits: An extremely fast growth rate, genetic tractability, and the ability to grow on a variety of carbon sources (“feedstock flexibility”). Given these inherent benefits, we sought to determine its potential to heterologously produce natural products, and chose beta-carotene and violacein as test cases. For beta-carotene production, we expressed the beta-carotene biosynthetic pathway from the sister marine bacterium Vibrio campbellii, as well as the mevalonate biosynthetic pathway from the Gram-positive bacterium Lactobacillus acidophilus to improve precursor abundance. Violacein was produced by expressing a biosynthetic gene cluster derived from Chromobacterium violaceum. Not only was V. natriegens able to heterologously produce these compounds in rich media, illustrating its promise as a new chassis for small molecule drug production, but it also did so in minimal media using a variety of feedstocks. The ability for V. natriegens to produce natural products with multiple industrially-relevant feedstocks argues for continued investigations into the production of more complex natural products in this chassis.