Molecular basis for the folding of β-helical autotransporter passenger domains

Xiaojun Yuan; Matthew D Johnson; Jing Zhang; Alvin W Lo; Mark A Schembri; Lakshmi C Wijeyewickrema; Robert N Pike; Gerard H M Huysmans; Ian R Henderson; Denisse L Leyton

doi:10.1038/s41467-018-03593-2

Molecular basis for the folding of β-helical autotransporter passenger domains

Nat Commun. 2018 Apr 11;9(1):1395. doi: 10.1038/s41467-018-03593-2.

Authors

Xiaojun Yuan¹, Matthew D Johnson¹, Jing Zhang¹, Alvin W Lo^{2

3}, Mark A Schembri^{2

3}, Lakshmi C Wijeyewickrema⁴, Robert N Pike⁴, Gerard H M Huysmans⁵, Ian R Henderson⁶, Denisse L Leyton^{7

8}

Affiliations

¹ Research School of Biology, Australian National University, Canberra, ACT, 0200, Australia.
² School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia.
³ Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, QLD, 4072, Australia.
⁴ Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia.
⁵ Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA.
⁶ Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK.
⁷ Research School of Biology, Australian National University, Canberra, ACT, 0200, Australia. [email protected].
⁸ Medical School, Australian National University, Canberra, ACT, 0200, Australia. [email protected].

Abstract

Bacterial autotransporters comprise a C-terminal β-barrel domain, which must be correctly folded and inserted into the outer membrane to facilitate translocation of the N-terminal passenger domain to the cell exterior. Once at the surface, the passenger domains of most autotransporters are folded into an elongated β-helix. In a cellular context, key molecules catalyze the assembly of the autotransporter β-barrel domain. However, how the passenger domain folds into its functional form is poorly understood. Here we use mutational analysis on the autotransporter Pet to show that the β-hairpin structure of the fifth extracellular loop of the β-barrel domain has a crucial role for passenger domain folding into a β-helix. Bioinformatics and structural analyses, and mutagenesis of a homologous autotransporter, suggest that this function is conserved among autotransporter proteins with β-helical passenger domains. We propose that the autotransporter β-barrel domain is a folding vector that nucleates folding of the passenger domain.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Sequence
Bacterial Toxins / chemistry*
Bacterial Toxins / genetics
Bacterial Toxins / metabolism
Binding Sites
Cloning, Molecular
Crystallography, X-Ray
Enterotoxins / chemistry*
Enterotoxins / genetics
Enterotoxins / metabolism
Escherichia coli / genetics*
Escherichia coli / metabolism
Escherichia coli Proteins / chemistry*
Escherichia coli Proteins / genetics
Escherichia coli Proteins / metabolism
Gene Expression
Genetic Vectors / chemistry
Genetic Vectors / metabolism
Kinetics
Models, Molecular
Protein Binding
Protein Conformation, alpha-Helical
Protein Conformation, beta-Strand
Protein Folding
Protein Interaction Domains and Motifs
Protein Transport
Recombinant Proteins / chemistry*
Recombinant Proteins / genetics
Recombinant Proteins / metabolism
Sequence Alignment
Sequence Homology, Amino Acid
Serine Endopeptidases / chemistry*
Serine Endopeptidases / genetics
Serine Endopeptidases / metabolism
Substrate Specificity
Thermodynamics
Type V Secretion Systems / chemistry*
Type V Secretion Systems / genetics
Type V Secretion Systems / metabolism

Substances

Bacterial Toxins
Enterotoxins
Escherichia coli Proteins
Recombinant Proteins
Type V Secretion Systems
EspP protein, E coli
Pet protein, E coli
Serine Endopeptidases