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Structural molecular biology of the type II bacterial secretion system

Background

The bacterial type II secretion system (T2SS) is responsible for several human diseases causing major fatalities and devastating crop loss. It comprises three components: an inner-membrane platform of proteins with associated cytoplasmic ATPase, periplasmic filamentous pilus proteins, and an outer membrane secretin. The secretin is known to form a dodecameric pore in the outer membrane and in several secretion systems is guided into place by a lipoprotein pilotin. There is a cryo-EM structure for the secretin and X-ray structures for the four secretin N-terminal periplasmic domains. The inner-membrane platform is formed by several proteins of which the structures of several periplasmic and cytoplasmic domains are known, but the stoichiometry of the proteins and their organization in the inner-membrane platform is not known.

There are four inner-membrane platform proteins: GspL, GspM, GspF and GspC. The inner-membrane platform proteins GspL, GspM and GspC span the membrane once, whereas GspF is predicted to have at least three transmembrane helices. The inner-membrane proteins are probably inserted into the membrane by the Sec machinery and GspC, GspL, and GspM have been shown to protect each other from proteolysis suggesting that they form a complex. It is not clear if the inner-membrane proteins assemble spontaneously or if they require the presence of the cytoplasmic ATPase, for assembly. Preliminary studies suggest that the presence of the cytoplasmic ATPase facilitates assembly of the inner-membrane platform components GspL amd GspM, its presence certainly enhances the quantity of recombinant GspL and GspM produced. It is possible, that the secretin and periplasmic proteins may also take a part in assembly of the inner-membrane platform, but this has not been demonstrated.

Project

The specific focus of this project is the inner-membrane proteins of the secretion system. We propose to use a combination of experimental methods and techniques, including computational techniques to investigate the inner-membrane subcomplex of this secretion system. Ultimately the knowledge may be helpful in preventing the human disease and increasing food security against bacterial damage.

Training

Training will be given in a range of techniques in structural and molecular biology including: protein crystallography and NMR spectroscopy, also of course in the production of proteins for structural studies. Training in molecular simulation will also be given.

Eligibility

Applicant requirements are listed on the CONACYT foreign scholarship pages.

Applicants with degrees in Biochemistry, Chemistry, or related subject appropriate for this project. Appropriate laboratory experience may be an advantage, but are not essential

.International students must provide evidence of proficient English language skills, see our entry requirements page for further information.

NB If you are interested in self-funding please contact Prof. Pickersgill by e-mail (r.w.pickersgill@qmul.ac.uk) to discuss your eligibility for this project.

Application process

  1. Potential candidates should contact Prof. Pickersgill by e-mail (r.w.pickersgill@qmul.ac.uk) and submit their CV and a cover letter explaining their eligibility and interest in this project.
  2. Applications to Queen Mary are accepted all year round but we encourage you to contact Prof. Pickersgill as soon as possible. If he agrees to take your application further you will be required to submit an online application.
  3. If you are successful we will give you an offer on the condition that you are given a funding award from CONACYT.
  4. When you have received a conditional offer from us, you should apply directly to CONACYT.

References

  • Rehman, S., Gu, S., Shevchik, V.E., Pickersgill, R.W. (2013) Anatomy of secretin-binding to the D. dadantii type II secretion system pilotin. Acta Crystallogr D Biol Crystallogr. 69, 1381-1386
  • Wang, X., Pineau, C., Gu, S., Guschinskaya, N., Pickersgill, R.W., Shevchik, V.E. (2012) Cysteine scanning mutagenesis and disulfide mapping analysis of the arrangement of GspC and GspD protomers within the T2SS. J. Biol. Chem. 287, 19082-19093.
  • Gu, S., Kelly, G., Shevchik, V., Pickersgill, R.W. (2012) Solution structure of the HR domain and its interaction with the outer membrane secretin of the type II secretion system. J. Biol. Chem. 287, 9072-9080.
  • Gu, S., Rehman, S., Shevchik, V.E., Pickersgill, R.W. (2012) Structural and functional insights into the pilotin-secretin complex of the type II secretion system. PLOS Pathogens 8: e1002531
  • Login, F., Fries, M., Pickersgill, R.W. & Shevchik, V. (2010) A 20-residue peptide of the inner membrane protein OutC mediates interaction with two distinct sites of the outer membrane secretin OutD and is essential for the functional type II secretion. Mol Micro. 76, 944-955.
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