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  1. Free, publicly-accessible full text available January 1, 2025
  2. Free, publicly-accessible full text available July 31, 2024
  3. Abstract

    Siderophores belonging to the ferrichrome family are essential for the viability of fungal species and play a key role for virulence of numerous pathogenic fungi. Despite their biological significance, our understanding of how these iron-chelating cyclic hexapeptides are assembled by non-ribosomal peptide synthetase (NRPS) enzymes remains poorly understood, primarily due to the nonlinearity exhibited by the domain architecture. Herein, we report the biochemical characterization of the SidC NRPS, responsible for construction of the intracellular siderophore ferricrocin. In vitro reconstitution of purified SidC reveals its ability to produce ferricrocin and its structural variant, ferrichrome. Application of intact protein mass spectrometry uncovers several non-canonical events during peptidyl siderophore biosynthesis, including inter-modular loading of amino acid substrates and an adenylation domain capable of poly-amide bond formation. This work expands the scope of NRPS programming, allows biosynthetic assignment of ferrichrome NRPSs, and sets the stage for reprogramming towards novel hydroxamate scaffolds.

     
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  4. null (Ed.)
    Protein transfer into nanoscale compartments is critical for many cellular/life processes, yet there are few reports on how compartment properties impact the protein orientation during a transfer. Such a knowledge gap limits a deeper understanding of the protein transfer mechanism, which could be bridged using nanoporous materials. Here, we use a mesoporous silica, a covalent organic framework, and a metal-organic framework with charged, hydrophobic, and neutral surfaces, respectively, to elucidate the impact of channel properties on the transfer of a model protein, lysozyme. Using site-directed spin labeling and time-resolved electron paramagnetic resonance spectroscopy, we reveal that the transfer can be a multi-step process depending on channel properties and depict the relative orientation changes of lysozyme upon transfer into each channel. To the best of our knowledge, this is the first structural insight into protein orientation upon transfer into different compartments, meaningful for the rational design of synthetic materials to host enzymes or mimic the cellular compartments. 
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  5. This paper presents the design, analysis, and experimental testing results for a 5.67:1 Halbach rotor magnetic gearbox with a ferromagnetic back support. Using 3-D finite element analysis software the Halbach magnetic gearbox was calculated to achieve a volumetric torque density of 284N·m/L with only an active region outer diameter of 120mm. The experimental prototype obtained an active region volumetric torque density of 261.4N·m/L 
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