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Unlocking the molecular mechanism of Sec-dependent protein translocation using molecular genetics

Primary Supervisor: Dr Damon Huber, School of Biosciences

Secondary supervisor: Manuel Banzhaf

PhD project title: Unlocking the molecular mechanism of Sec-dependent protein translocation using molecular genetics

University of Registration: University of Birmingham

Project outline:

Every compartment of a cell contains proteins, and yet all of these proteins are initially synthesised inside the cell in the cytoplasm. Proteins that do not normally reside inside the cytoplasmic compartment must be transported across one or several membrane in order to be localised to the correct compartment. In most cases, the first step in their correct localisation is transport across the cytoplasmic membrane by Sec machinery, which is conserved throughout evolution. The core Sec machinery has been extensively investigated in the model organism Escherichia coli. Proteins are transported through a channel in the cytoplasmic membrane (SecYEG). Transport through SecYEG is powered by an ATPase (SecA), and a number of additional components, including SecDF, YidC, YajC and SecB, assist protein transport. In addition, recent work by our group suggests that there is a much larger network of proteins that assists the Sec machinery, which we have termed Accessory Sec Components (or ASCs). However, despite decades of research, the molecular mechanism of Sec-dependent protein translocation is unclear. For example, YajC is an evolutionarily conserved protein that forms a stable complex with the Sec machinery, but it is not required for translocation of proteins across the cytoplasmic membrane under laboratory growth conditions. In addition, the large periplasmic domain of YidC is strongly conserved in the large family of Gram-negative bacteria, but the function of this domain is unclear. The goal of this project is to investigate the structure and function of the Sec machinery using cutting-edge molecular genetic approaches. These approaches include high-throughput genetic screening methods and cutting-edge methodologies in molecular genetics and biochemistry.


Examples of the type of work done our lab:

  1. Cranford Smith T, Wynne M, Carter C, Jiang C, Jamshad M, Milner MT, Djouider Y, Hutchinson E, Lund PA, Henderson I, Huber D. (2020) AscA (YecA) is a molecular chaperone involved in Sec-dependent protein translocation in Escherichia coli. BioRxiv 215244.
  2. Cranford-Smith T, Jamshad M, Jeeves M, Chandler RA, Yule J, Robinson A, Alam F, Dunne KA, Aponte Angarita EH, Alanazi M, Carter C, Henderson IR, Lovett JE, Winn P, Knowles T, Huber D. (2020) Iron is a ligand of SecA-like metal-binding domains in vivo. J Biol Chem. 295:7516-7528.

Literature review covering the background material:

  1. Cranford Smith T and Huber D. (2018) The way is the goal: how SecA transports proteins across the cytoplasmic membrane in bacteria. FEMS Microbiol Lett. 365, doi: 10.1093/femsle/fny093

BBSRC Strategic Research Priority: Understanding the Rules of Life:Microbiology & Systems Biology

Techniques that will be undertaken during the project:

  • Molecular biology
  • Molecular genetics
  • High-throughput sequencing
  • High-throughput screening
  • Bioinformatics

Contact: Dr Damon Huber, University of Birmingham