Dr Susan Howitt BSc, PhD (ANU)
Senior Lecturer
School of Biochemistry and Molecular Biology,
Faculty of Science,
Australian National University ,
Canberra , ACT,
Australia 0200
Personal Website Address: http://www.anu.edu.au/bambi/people/howitt.htm
Email: Susan.Howitt@anu.edu.au
The Big Question
My lab is trying to understand the molecular mechanisms of transporters involved in nutrient uptake. Such transporters play a vital role at the interface between plant and environment yet little is known of their mechanism of action. An understanding of the molecular mechanism involves identifying where and how substrate binds, how the transporter is energised, and obtaining structural information. This may eventually allow manipulation of transporters so that they are optimised for particular purposes, for example, nutrient limitation, a specific nutrient regime, bioremediation.
The Short-term goals
Our research is directed to understanding structure and function of sulphate and ammonium transporters from plants. Both sulphate and ammonium are essential nutrients that are taken up from the soil into the root cells via specific transporters. The approach taken is to use site-directed mutagenesis to alter single amino acid residues which are predicted to be essential for transporter function. The mutant transporters are then expressed in yeast so that their function can be analysed. By altering different amino acids both singly and in combinations we can build up a picture of important regions of the transporter and how they interact. The aim of this work is to provide information which will eventually allow an understanding of the molecular mechanism of these transporters.
| Group (lab) Members and areas of research
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- Rhianna Thompson
- Fiona Leves
Current
Expression and characterisation of nutrient transporters from the intracellular malaria parasite, Plasmodium falciparum. ARC Discovery grant to K. Kirk, S. Howitt and S Broer .
Applications submitted or planned
Structure and function of sulphate transporters from plants. To be submitted to ARC Discovery program.
| Techniques in the Laboratory
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Currently active
- Site-directed mutagenesis, cloning, PCR and other molecular biology
- Silicon oil transport measurements
- Isolation of yeast membranes by fractionation
- Western blotting
In development
- Heterologous expression systems for transport proteins from the malaria parasite, Plasmodium falciparum
Top three areas of knowledge
- Structure of membrane proteins
- Mechanisms of transport proteins
- eterologous expression of membrane proteins
Top three technical skills
- Expression of membrane proteins in yeast
- Nutrient transport measurements
- Molecular biology
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Shelden MC, Loughlin P, Tierney ML and Howitt SM (2003) Interactions between charged amino acid residues within transmembrane helices in the sulfate transporter SHST1. Biochemistry. 42:12941-9.
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Loughlin P, Shelden MC Tierney ML and Howitt SM (2002) Structure and function of a model member of the SulP family. Cell. Biochem. Biophys . 36:183-90.
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Harris RM, Webb DC, Howitt SM and Cox GB (2001) Characterization of PitA and PitB from Escherichia coli . J. Bacteriol . 183: 5008-5014.
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Shelden MC, Loughlin P, Tierney ML and Howitt SM (2001) Proline residues in two tightly coupled helices of the sulphate transporter, SHST1, are important for sulphate transport. Biochem. J . 356 : 589-594.
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