The Structure of a Conserved Domain of TamB Reveals a Hydrophobic β Taco Fold

Inokentijs Josts; Christopher James Stubenrauch; Grishma Vadlamani; Khedidja Mosbahi; Daniel Walker; Trevor Lithgow; Rhys Grinter

doi:10.1016/j.str.2017.10.002

The Structure of a Conserved Domain of TamB Reveals a Hydrophobic β Taco Fold

Structure. 2017 Dec 5;25(12):1898-1906.e5. doi: 10.1016/j.str.2017.10.002. Epub 2017 Nov 9.

Authors

Inokentijs Josts¹, Christopher James Stubenrauch², Grishma Vadlamani², Khedidja Mosbahi³, Daniel Walker³, Trevor Lithgow², Rhys Grinter⁴

Affiliations

¹ The Hamburg Centre for Ultrafast Imaging (CUI), Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany; Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany.
² Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, VIC 3804, Australia.
³ Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
⁴ Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, VIC 3804, Australia; Institute of Microbiology and Infection, School of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK. Electronic address: rhys.grinter@monash.edu.

Abstract

The translocation and assembly module (TAM) plays a role in the transport and insertion of proteins into the bacterial outer membrane. TamB, a component of this system spans the periplasmic space to engage with its partner protein TamA. Despite efforts to characterize the TAM, the structure and mechanism of action of TamB remained enigmatic. Here we present the crystal structure of TamB amino acids 963-1,138. This region represents half of the conserved DUF490 domain, the defining feature of TamB. TamB_963-1138 consists of a concave, taco-shaped β sheet with a hydrophobic interior. This β taco structure is of dimensions capable of accommodating and shielding the hydrophobic side of an amphipathic β strand, potentially allowing TamB to chaperone nascent membrane proteins from the aqueous environment. In addition, sequence analysis suggests that the structure of TamB_963-1138 is shared by a large portion of TamB. This architecture could allow TamB to act as a conduit for membrane proteins.

Keywords: Escherichia coli; TamB; X-ray crystallography; chaperone; membrane biology; microbiology; protein assembly.

Publication types

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

MeSH terms

Amino Acid Motifs
Bacterial Outer Membrane Proteins / chemistry*
Bacterial Outer Membrane Proteins / metabolism
Conserved Sequence*
Escherichia coli Proteins / chemistry*
Escherichia coli Proteins / metabolism
Hydrophobic and Hydrophilic Interactions
Protein Domains

Substances

Bacterial Outer Membrane Proteins
Escherichia coli Proteins

Abstract

Publication types

MeSH terms

Substances

Grants and funding