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Title: Structural and functional studies of conserved nucleotide-binding protein LptB in lipopolysaccharide transport

Highlights: • Determination of the structure of the wild-type LptB in complex with ATP and Mg{sup 2+}. • Demonstrated that ATP binding residues are essential for LptB’s ATPase activity and LPS transport. • Dimerization is required for the LptB’s function and LPS transport. • Revealed relationship between activity of the LptB and the vitality of E. coli cells. - Abstract: Lipopolysaccharide (LPS) is the main component of the outer membrane of Gram-negative bacteria, which plays an essential role in protecting the bacteria from harsh conditions and antibiotics. LPS molecules are transported from the inner membrane to the outer membrane by seven LPS transport proteins. LptB is vital in hydrolyzing ATP to provide energy for LPS transport, however this mechanism is not very clear. Here we report wild-type LptB crystal structure in complex with ATP and Mg{sup 2+}, which reveals that its structure is conserved with other nucleotide-binding proteins (NBD). Structural, functional and electron microscopic studies demonstrated that the ATP binding residues, including K42 and T43, are crucial for LptB’s ATPase activity, LPS transport and the vitality of Escherichia coli cells with the exceptions of H195A and Q85A; the H195A mutation does not lower its ATPase activity but impairs LPS transport,more » and Q85A does not alter ATPase activity but causes cell death. Our data also suggest that two protomers of LptB have to work together for ATP hydrolysis and LPS transport. These results have significant impacts in understanding the LPS transport mechanism and developing new antibiotics.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [2] ;  [4] ;  [5] ;  [6] ; ;  [4] ;  [7] ;  [1]
  1. Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, NR4 7TJ (United Kingdom)
  2. (China)
  3. (United Kingdom)
  4. College of Life Sciences, Sichuan University, Chengdu 610065 (China)
  5. Biomedical Sciences Research Complex, School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST (United Kingdom)
  6. School of Electronics and Information, Wuhan Technical College of Communications, No. 6 Huangjiahu West Road, Hongshan District, Wuhan, Hubei 430065 (China)
  7. Laboratory of Department of Surgery, The First Affiliated Hospital, Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, Guangdong 510080 (China)
Publication Date:
OSTI Identifier:
22416746
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 452; Journal Issue: 3; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ANTIBIOTICS; APOPTOSIS; ATP; CELL MEMBRANES; CRYSTAL STRUCTURE; DIMERIZATION; ELECTRONS; ESCHERICHIA COLI; HYDROLYSIS; LIPOPOLYSACCHARIDES; MOLECULES; MUTATIONS; PROTEINS; RESIDUES