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Crystal structure of the bacterial protein export chaperone SecB

Nature Structural Biology volume 7, pages 1172–1177 (2000)Cite this article

Abstract

SecB is a bacterial molecular chaperone involved in mediating translocation of newly synthesized polypeptides across the cytoplasmic membrane of bacteria. The crystal structure of SecB from Haemophilus influenzae shows that the molecule is a tetramer organized as a dimer of dimers. Two long channels run along the side of the molecule. These are bounded by flexible loops and lined with conserved hydrophobic amino acids, which define a suitable environment for binding non-native polypeptides. The structure also reveals an acidic region on the top surface of the molecule, several residues of which have been implicated in binding to SecA, its downstream target.

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Figure 1: The structure of the SecB monomer.
Figure 2: The quaternary structure of the SecB molecule.
Figure 3: The proposed peptide binding channel.
Figure 4: The proposed SecA binding site.

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Acknowledgements

We thank J. Stuckey for maintaining the X-ray facility at the University of Michigan Medical School and for assistance on synchrotron data collection; M. Marletta and D. Peisach for access to their SGI graphic workstation during structure fitting and refinement; K. Brister for access and help at APS BioCARs beamlines; J. Dixon, M. Marletta, K. Orth and R. Taussig for critically reading the manuscript. This work was supported by an NIH grant to Z.X. and the University of Michigan Biological Scholar Program.

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  1. Department of Biological Chemistry, The University of Michigan Medical School, 1301 E. Catherine Road, Ann Arbor, 48109, Michigan, USA

    Zhaohui Xu, John D. Knafels & Kae Yoshino

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  1. Zhaohui Xu
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  2. John D. Knafels
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  3. Kae Yoshino
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Correspondence to Zhaohui Xu.

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Xu, Z., Knafels, J. & Yoshino, K. Crystal structure of the bacterial protein export chaperone SecB. Nat Struct Mol Biol 7, 1172–1177 (2000). https://doi.org/10.1038/82040

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