Crystal structure of the pilotin from the enterohemorrhagic Escherichia coli type II secretion system

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Bacteria contain several sophisticated macromolecular machineries responsible for translocating proteins across the cell envelope. One prominent example is the type II secretion system (T2SS), which contains a large outer membrane channel, called the secretin. These gated channels require specialized proteins, so-called pilotins, to reach and assemble in the outer membrane. Here we report the crystal structure of the pilotin GspS from the T2SS of enterohemorrhagic Escherichia coli (EHEC), an important pathogen that can cause severe disease in cases of food poisoning. In this four-helix protein, the straight helix α2, the curved helix α3 and the bent helix α4 surround the central N-terminal helix α1. The helices of GspS create a prominent groove, mainly formed by side chains of helices α1, α2 and α3. In the EHEC GspS structure this groove is occupied by extra electron density which is reminiscent of an α-helix and corresponds well with a binding site observed in a homologous pilotin. The residues forming the groove are well conserved among homologs, pointing to a key role of this groove in this class of T2SS pilotins. At the same time, T2SS pilotins in different species can be entirely different in structure, and the pilotins for secretins in non-T2SS machineries have yet again unrelated folds, despite a common function. It is striking that a common complex function, such as targeting and assembling an outer membrane multimeric channel, can be performed by proteins with entirely different folds.

Original languageEnglish
Pages (from-to)186-191
Number of pages6
JournalJournal of Structural Biology
Issue number2
StatePublished - May 2013

Bibliographical note

Funding Information:
We thank Stewart Turley for assistance during data collection and Steve Moseley for providing E. coli O157:H7 DNA. We thank the staff of the Berkeley Center for Structural Biology and the Stanford Synchrotron Radiation Light source for support during data collection. The Berkeley Center for Structural Biology is supported in part by the National Institutes of Health, National Institute of General Medical Sciences, and the Howard Hughes Medical Institute. The Advanced Light Source is supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Stanford Synchrotron Radiation Lightsource, a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Stanford University. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research, and by the National Institutes of Health, National Institute of General Medical Sciences (including P41GM103393) and the National Center for Research Resources (P41RR001209). This study was supported by National Institutes of Health Grant AI34501 (to WGJH). The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of NIGMS, NCRR or NIH.


  • Crystal structure
  • EtpO
  • Hamburger disease
  • Lipoprotein
  • Secretin
  • Type II secretion

ASJC Scopus subject areas

  • Structural Biology


Dive into the research topics of 'Crystal structure of the pilotin from the enterohemorrhagic Escherichia coli type II secretion system'. Together they form a unique fingerprint.

Cite this