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The ketoreductase (KR) domain in the first extending module of the polyketide synthase (PKS) catalyzes the reductions of both an α-keto group and a β-keto group in the biosynthesis of bacillaene, suggesting the intrinsic substrate promiscuity. In order to further investigate the substrate specificity, the KR domain (BacKR1) was heterologously overexpressed in Escherichia coli. In vitro enzymatic analysis showed that only one of the four diastereomers was formed in the reduction of the racemic (±)-2-methyl-3-oxopentanoyl-N-acetylcysteamine thioester catalyzed by BacKR1. In addition, BacKR1 was revealed to catalyze the reductions of cyclohexanone and p-chloroacetophenone, indicating the potential of KR domians of PKSs as biocatalysts.
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Curr Opin Microbiol
September 2025
Cryptosporidiosis Laboratory, The Francis Crick Institute, London, United Kingdom. Electronic address:
The movement of molecules across the membranous barriers of a cell is fundamental to cellular homeostasis in every living organism. This vital process is facilitated through a mechanistically diverse class of proteins, collectively known as membrane transporters. Among these are so-called carrier proteins that can function in passive and active transport mechanisms.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Department of Chemistry, Boston University, 590 Commonwealth Ave, Boston, Massachusetts 02215, United States.
The cytosolic iron-sulfur cluster assembly (CIA) targeting complex maturates over 30 cytosolic and nuclear Fe-S proteins, raising the question of how a single complex recognizes such a diverse set of clients. The discovery of a C-terminal targeting complex recognition (TCR) peptide in up to 25% of CIA clients provided a clue to substrate specificity, yet the molecular and energetic basis for this interaction remained unresolved. By integrating computational and biochemical approaches, we show that the TCR peptide binds a conserved interface between the Cia1 and Cia2 subunits of the targeting complex, even in the absence of the Fe-S cluster.
View Article and Find Full Text PDFJ Agric Food Chem
September 2025
College of Food Science and Engineering, Ocean University of China, Qingdao 266404, PR China.
Sulfated fucan has attracted growing attention due to its diverse biological properties. Endo-1,3-fucanases are valuable tools for the degradation of sulfated fucan. This study characterized an endo-1,3-fucanase Fun174Sb from the GH174 family, utilizing a combination of protein crystallography, mutagenesis, computational biology, and nuclear magnetic resonance techniques.
View Article and Find Full Text PDFArch Microbiol
September 2025
College of Bioengineering, Sichuan University of Science and Engineering, Zigong, 643000, China.
The esterase gene encoding EstJN1 of Clostridium butyricum, which was isolated from the pit cellar of Chinese liquor facility, was expressed. EstJN1 was identified as a novel GDSL esterase belonging to family II. The enzyme demonstrated a marked substrate preference for p-nitrophenyl butyrate, with optimal activity at a temperature of 40 ℃ and a pH of 7.
View Article and Find Full Text PDFJ Labelled Comp Radiopharm
September 2025
National Key Laboratory for the Development and Utilization of Forest Food Resources, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, Jiangsu, China.
Carbon-11 (C)-labeled radiotracers are invaluable tools in positron emission tomography (PET), enabling real-time visualization of biochemical processes with high sensitivity and specificity. Among the various C synthons, cyclotron-produced [C]CO is a fundamental precursor, though its direct incorporation into complex molecules has traditionally been limited by its low reactivity, gaseous form, and short half-life. Recent advances in [C]CO fixation chemistry through both nonphotocatalytic and photocatalytic methods have significantly expanded its utility in the synthesis of structurally diverse compounds, including carboxylic acids, carbonates, carbamates, amides, and ureas.
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