Structure and function of the Escherichia coli Tol-Pal stator protein TolR.
TolR is a 15-kDa inner membrane protein subunit of the Tol-Pal complex in Gram-negative bacteria, and its function is poorly understood. Tol-Pal is recruited to cell division sites where it is involved in maintaining the integrity of the outer membrane. TolR is related to MotB, the peptidoglycan (PG)-binding stator protein from the flagellum, suggesting it might serve a similar role in Tol-Pal. The only structure thus far reported for TolR is of the periplasmic domain from Haemophilus influenzae in which N- and C-terminal residues had been deleted (TolR(62-133), Escherichia coli numbering). H. influenzae TolR(62-133) is a symmetrical dimer with a large deep cleft at the dimer interface. Here, we present the 1.7-Å crystal structure of the intact periplasmic domain of E. coli TolR (TolR(36-142)). E. coli TolR(36-142) is also dimeric, but the architecture of the dimer is radically different from that of TolR(62-133) due to the intertwining of its N and C termini. TolR monomers are rotated ∼180° relative to each other as a result of this strand swapping, obliterating the putative PG-binding groove seen in TolR(62-133). We found that removal of the strand-swapped regions (TolR(60-133)) exposes cryptic PG binding activity that is absent in the full-length domain. We conclude that to function as a stator in the Tol-Pal complex dimeric TolR must undergo large scale structural remodeling reminiscent of that proposed for MotB, where the N- and C-terminal sequences unfold in order for the protein to both reach and bind the PG layer ∼90 Å away from the inner membrane.
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU and.
Justyna A
JA
Wojdyla
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU and.
Erin
E
Cutts
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU and.
Renata
R
Kaminska
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU and.
Grigorios
G
Papadakos
the Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
Jonathan T S
JT
Hopper
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU and.
Phillip J
PJ
Stansfeld
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU and.
David
D
Staunton
the Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
Carol V
CV
Robinson
From the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU and colin.kleanthous@bioch.ox.ac.uk.
Colin
C
Kleanthous
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000737:chemistry / Q000378:metabolism; D015870:Gene Expression; D057927:Hydrophobic and Hydrophilic Interactions; D008074:Lipoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010457:Peptidoglycan / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019897:Periplasm / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C031163:ExcC protein, E coli; D008074:Lipoproteins; D008565:Membrane Proteins; C064779:MotB protein, Bacteria; D010457:Peptidoglycan; D011994:Recombinant Proteins; C060794:tolR protein, E coli
Escherichia coli (E. coli); TolR; bacteria; crystal structure; dimerization; domain; membrane protein; periplasm; strand-swapped