Poster Presentation The 47th Lorne Conference on Protein Structure and Function 2022

Structural characterization of a Type B chloramphenicol acetyltransferase from the emerging pathogen Elizabethkingia anophelis NUHP1 and screening for a potential inhibitor using a molecular docking approach (#165)

Seyedmohammad Ghafoori 1 , Alyssa M. Robles 2 , Angelika M. Arada 2 , Paniz Shirmast 1 , David M. Dranow 3 4 , Stephen J. Mayclin 3 4 , Donald D. Lorimer 3 4 , Peter J. Myler 3 5 , Thomas E. Edwards 3 4 , Misty L. Kuhn 2 , Jade K. Forwood 1
  1. School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
  2. Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, USA
  3. Seattle Structural Genomics Center for Infectious Disease, Seattle, WA, USA
  4. UCB Pharma, Bainbridge Island, WA, USA
  5. Seattle Children’s Research Institute, University of Washington, Seattle, WA, USA

Elizabethkingia anopheles is a member of the large family of Flavobacteriaceae and an emerging multidrug-resistant pathogen responsible for several global outbreaks. Antibiotic resistance genes are found within the E. anophelis genome, including chloramphenicol acetyltransferases (CATs). These enzymes play significant roles in antibiotic resistance and can be transferred in mobile genetic elements. CATs reduce the effectiveness of the antibiotic chloramphenicol by catalysing the acetylation of the enzyme. Here we determined the high-resolution crystal structure of a CAT protein from the E. anophelis NUHP1 strain that caused a Singaporean outbreak. We screen more than 500 natural products derived from plants to find a potential CAT inhibitor using a molecular docking approach. Its structure does not resemble that of classical Type A CATs, but rather, exhibits significant similarity to other previously characterized Type B (CatB) proteins from Pseudomonas aeruginosa, Vibrio cholerae and Vibrio vulnificus, which adopt a hexapeptide repeat fold. Moreover, the CAT protein from E. anophelis displays high sequence similarity to other clinically validated chloramphenicol resistance genes, indicating it may also play a role in resistance to this antibiotic. Using bioinformatics approaches, we found Acemannan as a potential inhibitor for the CAT enzyme, acting as an antagonist at both Chloramphenicol and Acetyl-CoA binding sites. Our work expands the very limited structural and functional coverage of proteins from Flavobacteriaceae pathogens which are becoming increasingly more problematic.

  1. Ghafoori SM, Robles AM, Arada AM, Shirmast P, Dranow DM, Mayclin SJ, Lorimer DD, Myler PJ, Edwards TE, Kuhn ML, Forwood JK. Structural characterization of a Type B chloramphenicol acetyltransferase from the emerging pathogen Elizabethkingia anophelis NUHP1. Sci Rep. 2021 May 4;11(1):9453. doi: 10.1038/s41598-021-88672-z. PMID: 33947893; PMCID: PMC8096840.