Premium
Structural basis for substrate selection by the translocation and assembly module of the β‐barrel assembly machinery
Author(s) -
Bamert Rebecca S.,
Lundquist Karl,
Hwang Hyea,
Webb Chaille T.,
Shiota Takoya,
Stubenrauch Christopher J.,
Belousoff Mathew J.,
Goode Robert J. A.,
Schittenhelm Ralf B.,
Zimmerman Richard,
Jung Martin,
Gumbart James C.,
Lithgow Trevor
Publication year - 2017
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13757
Subject(s) - bama , barrel (horology) , biology , folding (dsp implementation) , bacterial outer membrane , microbiology and biotechnology , protein folding , substrate (aquarium) , biophysics , computational biology , biochemistry , gene , materials science , engineering , escherichia coli , electrical engineering , composite material , ecology
Summary The assembly of proteins into bacterial outer membranes is a key cellular process that we are only beginning to understand, mediated by the β‐barrel assembly machinery (BAM). Two crucial elements of that machinery are the core BAM complex and the translocation and assembly module (TAM), with each containing a member of the Omp85 superfamily of proteins: BamA in the BAM complex, TamA in the TAM. Here, we used the substrate protein FimD as a model to assess the selectivity of substrate interactions for the TAM relative to those of the BAM complex. A peptide scan revealed that TamA and BamA bind the β‐strands of FimD, and do so selectively. Chemical cross‐linking and molecular dynamics are consistent with this interaction taking place between the first and last strand of the TamA barrel domain, providing the first experimental evidence of a lateral gate in TamA: a structural element implicated in membrane protein assembly. We suggest that the lateral gates in TamA and BamA provide different environments for substrates to engage, with the differences observed here beginning to address how the TAM can be more effective than the BAM complex in the folding of some substrate proteins.