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In Gram-negative bacteria, lipopolysaccharide transport (Lpt) protein LptA and LptC form a complex to transport LPS from the inner membrane (IM) to the outer membrane (OM). Blocking the interaction between LptA and LptC will lead to the defect of OM and cell death. Therefore, Lpt protein interaction could be used as a target to screen new drugs for killing Gram-negative bacteria. Here we used biolayer interferometry (BLI) assay to detect the interaction between LptA and LptC, with the aim to develop a method for screening the LptA/LptC interaction blockers in vitro. Firstly, LptC and LptA with or without signal peptide (LptAfull or LptAno signal) were expressed in E. coli BL21(DE3). The purified proteins were then labeled with biotin and the super streptavidin (SSA) biosensor was blocked with diluent. The biotin labeled protein sample was mixed with the sensor, and then the binding of the protein with a series of diluted non biotinylated protein was detected. At the same time, non-biotinylated protein was used as a control. The binding of biotinylated protein to a small molecule IMB-881 and the blocking of interaction were also detected by the same method. In the blank control, the biosensor without biotinylated protein was used to detect the serially diluted samples. The signal response constant was calculated by using steady analysis. The results showed that biotinylated LptC had a good binding activity with LptAfull and LptAno signal with KD value 2.9e⁻⁷±7.9e⁻⁸ and 6.0e⁻⁷±2.8e⁻⁸, respectively; biotinylated LptAno signal had a good binding activity with LptC, with a KD value of 9.6e⁻⁷±7.2e⁻⁸. All binding curves showed obvious fast binding and fast dissociation morphology. The small molecule compound IMB-881 can bind to LptA to block the interaction between LptA and LptC, but has no binding activity with LptC. In summary, we developed a method for detecting the LptA/LptC interaction based on the BLI technology, and confirmed that this method can be used to evaluate the blocking activity of small molecule blockers, providing a new approach for the screening of LptA/LptC interaction blockers.
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http://dx.doi.org/10.13345/j.cjb.200709 | DOI Listing |
Eur J Med Chem
May 2025
State Key Laboratory of Bioactive Substances and Function of Natural Medicines, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China. Electronic address:
The prevalence of MDR Gram-negative bacteria has posed a great impetus for the discovery of new therapeutic approaches. Here, we synthesized a series of pyrylium derivatives as antibiotic adjuvants based on IMB-0042, and evaluated their activities against Acinetobacter baumannii (A. baumannii) and Escherichia coli (E.
View Article and Find Full Text PDFBioorg Med Chem
March 2025
Beijing Key Laboratory of Technology and Application for Anti-Infective New Drugs Research and Development, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China. Electronic address:
Infectious diseases caused by drug-resistant bacteria represent one of the most significant global public challenges of this century. There is an urgent need for the treatment of drug-resistant Gram-negative bacterial infections. A series of 3,4-dihydro-2H-[1,3]oxazino[5,6-h]quinoline derivatives were synthesized and evaluated for their antibacterial activity against Gram-negative bacteria including strains from ATCC and clinical isolates, initially revealing the structure-activity relationship.
View Article and Find Full Text PDFMolecules
April 2024
Key Laboratory of Mass Spectrometry Imaging and Metabolomics (Minzu University of China), National Ethnic Affairs Commission, Beijing 100081, China.
Antibiotic resistance in Gram-negative bacteria remains one of the most pressing challenges to global public health. Blocking the transportation of lipopolysaccharides (LPS), a crucial component of the outer membrane of Gram-negative bacteria, is considered a promising strategy for drug discovery. In the transportation process of LPS, two components of the LPS transport (Lpt) complex, LptA and LptC, are responsible for shuttling LPS across the periplasm to the outer membrane, highlighting their potential as targets for antibacterial drug development.
View Article and Find Full Text PDFAppl Magn Reson
March 2024
Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226 USA.
The majority of pathogenic Gram-negative bacteria benefit from intrinsic antibiotic resistance, attributed primarily to the lipopolysaccharide (LPS) coating of the bacterial envelope. To effectively coat the bacterial cell envelope, LPS is transported from the inner membrane by the LPS transport (Lpt) system, which comprises seven distinct Lpt proteins, LptA-G, that form a stable protein bridge spanning the periplasm to connect the inner and outer membranes. The driving force of this process, LptBFG, is an asymmetric ATP binding cassette (ABC) transporter with a novel architecture and function that ejects LPS from the inner membrane and facilitates transfer to the periplasmic bridge.
View Article and Find Full Text PDFProtein Sci
February 2024
Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
Lipopolysaccharide (LPS) synthesis in Gram-negative bacteria is completed at the outer leaflet of the inner membrane (IM). Following synthesis, seven LPS transport (Lpt) proteins facilitate the movement of LPS to the outer membrane (OM), an essential process that if disrupted at any stage has lethal effects on bacterial viability. LptB FG, the IM component of the Lpt bridge system, is a type VI ABC transporter that provides the driving force for LPS extraction from the IM and subsequent transport across a stable protein bridge to the outer leaflet of the OM.
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