Protein Targeting and Molecular Machines Laboratory

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Professor Trevor Lithgow

ARC Federation Fellow

Tel:      +61-3-9902 9217

Fax:     +61-3-9905 3726

Office:   Room 252, Level 2, Building 76

Reception: Building 77, Science Technology Research & Innovation Precinct

Email:                      Trevor.Lithgow@monash.edu
Personal Assistant:  Yvonne.Dooley@monash.edu

A major global issue is the rise of antibiotic-resistance in bacterial pathogens. In response, new drug targets need to be identified and new vaccines need to be developed. Fundamental aspects of bacterial cell biology need to be understood if we are to take creative approaches to defeating these "new" bacterial pathogens. Our lab works on protein targeting; how proteins are transported to their correct sub-cellular location. My interests are particularly focused at how bacterial proteins are targeted to outer membranes: the targeting machinery is an excellent target for new drugs and the surface-exposed nature of the machinery means that it could serve as a basis in new vaccine strategies.

Work in my laboratory falls into two broad themes: (i) the evolution of protein transport machines and (ii) the mechanism by which protein transporters function. We are particularly interested in comparative analysis of the protein transport machines found in bacteria and in mitochondria; the two are related through evolution and each provides clues to understanding the mechanism by which proteins are transported to outer membranes.

We are members of the NHMRC Program in Cellular Microbiology, comprised of nodes at Monash University, the University of Queensland and the University of Melbourne.

We work together with other members of the Unit for Host-Pathogen Molecular Biology at Monash University.

Scholarship support is available to new PhD students. PhD postgraduate scholarships are available for Australian citizens or permanent residents with a H1 Honours degree. We have positions for international students: applicants are advised to check the Graduate studies web pages for information on entry requirements, tuition fee, and scholarships prior to application.

Students trained in this lab become expert in areas of molecular biology, cell biology and microbial biology. The Lithgow Lab Alumni can be found here

Evolution of Protein Transport Machines

Mitochondria in our cells evolved from an intracellular bacterium that initially served to provide ATP to the earliest eukaryotic cells. Our work showed that the protein transport machines in mitochondria evolved from the machinery that was already present in the ancestral bacteria. Thus, the assembly process(es) for outer membrane proteins are conserved in mitochondria and bacteria.

Link to the above article published in Science

Mechanisms of Protein Transport and Assembly

Much of our current research aims at characterizing the function of protein transport machines in bacteria - using knowledge of the mitochondrial and other systems, and expertise in genetics, biochemistry and cell biology. We are working to understand how bacterial pathogens assemble protein transport machines in their outer membranes, and how these function to target "effector" proteins into human cells.
Honours and postgraduate projects employ a broad range of techniques in molecular biology, genetics, computer science and cell biology. New projects on offer include:

• Characterization of the range of membrane protein substrates assembled by the newly discovered "Transport and Assembly Module" in bacterial outer membranes. The TAM assists the BAM complex to assemble autotransporters, but probably also other protein factors, into bacterial outer membranes.
  
• Understanding the assembly of the outer membrane components of the Type 2 and 3 secretion systems (T2SS, T3SS) in EPEC (pathogenic Escherichia coli) and Salmonella spp. This project keys into larger collaborative studies with Associate Professor Rohan Teasdale (University of Queensland) and Professor Liz Hartland (University of Melbourne). A combination of bioinformatics, high-throughput RNAi and biochemical assays will be used for identification and characterization of the transporters.
  

• Characterization of the targeting lipids and proteins into the outer membrane of Klebsiella pneumoniae. This project is in collaboration with Professor Dick Strugnell (University of Melbourne). A combination of bioinformatics, mass spectrometry, atomic force microscopy and biochemical assays will be used for identification and characterization of the transporters responsible for assembly of the outer membrane and capsule.
  
• Defining how integral membrane proteins are assembled into the mitochondrial outer membrane. This project will make use of yeast genetics and biochemical assays. Good evidence suggests a conserved mechanism is behind the assembly of tail-anchored proteins such as the Bcl-2 family and proteins with more complicated topologies such as beta-barrels.

  Lab Members

  

  Back row (L to R): Victoria Hewitt, Miguel Shingu-Vasquez, Chaille Webb, Hsin-Hui Shen
  Front row (L to R): Trevor Lithgow, Matthew Belousoff, Denisse Leyton, Rhys Dunstan, Eva Heinz

  Some Recent Publications from the Lithgow Lab

  • Dunstan R, Heinz E, Wijeyewickrema L, Pike R, Purcell A, Evans T, Praszkier J, Robins-Browne R, Strugnell R, Korotkov K & Lithgow T. (2013) Assembly of the Type II Secretion System such as Found in Vibrio cholerae Depends on the Novel Pilotin AspS. PLoS Pathog. 9: e1003117
    
  • Selkrig J, Mosbahi K, Webb C, Belousoff MJ, Perry A, Wells T, Morris F, Leyton D, Totsika M, Phan M, Celik N, Kelly M, Oates C, Hartland E, Robins-Browne R, Ramarathinam S, Purcell A, Schembri M, Strugnell R, Henderson I, Walker D & Lithgow T. (2012) Discovery of an archetypal protein transport system in bacterial outer membrane. Nat. Struct. Mol. Biol. 19: 506-10
    
  • Hewitt V, Heinz E, Shingu-Vazquez M, Qu Y, Jelicic B, Lo T, Beilharz T, Dumsday G, Gabriel K, Traven A & Lithgow T. (2012) A model system for mitochondrial biogenesis reveals evolutionary rewiring of protein import and membrane assembly pathways. Proc. Natl. Acad. Sci. 109: E3358-66
    
  • Dolezal P, Aili M, Tong J, Jiang JH, Marobbio CM, Lee S, Schuelein R, Belluzzo S, Binova E, Mousnier A, Frankel G, Giannuzzi G, Palmieri F, Gabriel K, Naderer T, Hartland E & Lithgow T. (2012) Legionella pneumophila secretes a mitochondrial carrier protein during infection. PLoS Pathog. 8: e1002459
    
  • Alcock F, Clements A, Webb C & Lithgow T. (2010) Evolution. Tinkering inside the organelle. Science 327: 649-50
    
  • Dolezal P, Likić V, Tachezy J & Lithgow T. (2006) Evolution of the molecular machines for protein import into mitochondria. Science 313: 314-8
    
  • Clements A, Bursac D, Gatsos X, Perry A, Civciristov S, Celik N, Likić V, Poggio S, Jacobs-Wagner C, Strugnell R & Lithgow T. (2009) The reducible complexity of a mitochondrial molecular machine. Proc. Natl. Acad. Sci. 106: 15791-5
    
  • Chacinska A, Koehler C, Milenkovic D, Lithgow T & Pfanner N. (2009) Importing mitochondrial proteins: machineries and mechanisms. Cell 138: 628-44

  
  Prof Lithgow's PubMed publications list

  Prof Lithgow's biography