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Title: Selective molecular transport through the protein shell of a bacterial microcompartment organelle

Bacterial microcompartments are widespread prokaryotic organelles that have important and diverse roles ranging from carbon fixation to enteric pathogenesis. Current models for microcompartment function propose that their outer protein shell is selectively permeable to small molecules, but whether a protein shell can mediate selective permeability and how this occurs are unresolved questions. In this paper, biochemical and physiological studies of structure-guided mutants are used to show that the hexameric PduA shell protein of the 1,2-propanediol utilization (Pdu) microcompartment forms a selectively permeable pore tailored for the influx of 1,2-propanediol (the substrate of the Pdu microcompartment) while restricting the efflux of propionaldehyde, a toxic intermediate of 1,2-propanediol catabolism. Crystal structures of various PduA mutants provide a foundation for interpreting the observed biochemical and phenotypic data in terms of molecular diffusion across the shell. Finally and overall, these studies provide a basis for understanding a class of selectively permeable channels formed by nonmembrane proteins.
 [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [4] ;  [1]
  1. Iowa State Univ., Ames, IA (United States). Roy J. Carver Dept. of Biochemistry, Biophysics, and Molecular Biology
  2. Univ. of California, Los Angeles, CA (United States). Molecular Biology Inst.
  3. Univ. of California, Los Angeles, CA (United States). UCLA-DOE Inst. for Genomics and Proteomics
  4. Univ. of California, Los Angeles, CA (United States). Molecular Biology Inst. UCLA-DOE Inst. for Genomics and Proteomics. Dept. of Chemistry and Biochemistry
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC02-06CH11357; 5P41RR015301-10; 8 P41 GM103403-10; R01AI081146; T32-GM008496
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 10; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Iowa State Univ., Ames, IA (United States); Univ. of California, Los Angeles, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Inst. of Health (NIH) (United States)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; microcompartment; protein channel; carboxysome; Salmonella; B12