One of the enzymes that are activated through redox networks, is ribonucleotide reductase (RNR), the only source for the de novo synthesis of deoxyribonucleotides needed for DNA replication and repair in all living organisms. In the Firmicutes bacteria there are two classes of RNR, one aerobic and one anaerobic class, and both are activated by flavin-based networks. Since these pathways are unique for bacteria they are also potential drug targets, therefore a deeper understanding of these activation pathways are important. A PhD-student are currently studying the anaerobic RNR class in Lactococcus lactis, and the master project will be in close collaboration with her to characterise the flavin proteins involved in the activation of this system. These flavin proteins have previously not been studied in L. Lactis, and the bacteria contains one flavodoxin reductase (FNR) and one flavodoxin (Fld), in addition to another Fld-like protein NrdI for activation of the aerobic RNR.
The main goal is to understand the structural basis for the activation of the anaerobic RNR by the FNR and Fld, through understanding the interaction and electron transfer between these proteins. The L. lactis contains as mentioned only one FNR and one Fld, while the other Firmicutes we have studies Bacillus cereus contains three FNRs and two Flds, so your studies on L. lactis will be compared to the B. cereus to elucidate how efficient are the systems with only one choice compared to the bacteria with several choices of redox partner proteins. To be able to answer these questions you will need to express and purify the proteins, solve the structure of them and do some biochemical and biophysical characterization.
Methods you will use and learn: Protein expression, purification, crystallisation and solving the structure of proteins with protein crystallography, enzyme kinetics, binding studies, redox potential measurements, anaerobic work and spectroscopic charaterisation. Data collection for solving the structures will involve travelling abroad to synchrotrons. The biophysical and biochemical methods used in this master project will to a large extend be covered in MBV4020, taught by the supervisors. Through the master project, you will also learn to present your work orally through group meetings and through posters presentations at scientific conferences.
Supervision: The master project will be performed in the Structural Redox Biochemistry Team (Section for Biochemistry and Molecular Biology) and supervised by Hans-Petter Hersleth, Hedda Johannesen and Marta Hammerstad.
Contact: Hans-Petter Hersleth room 2313, e-mail: h.p.hersleth@ibv.uio.no
To read more see our group homepage: http://hersleth.org/
Some relevant references:
M. Lofstad, I. Gudim, M. Hammerstad, Å.K. Røhr & H.-P. Hersleth
Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus.
Biochemistry (2016), 55, 4998-5001. [Link]
M. Hammerstad, H.-P. Hersleth, A.B. Tomter, Å.K. Røhr & K.K. Andersson
Crystal Structure of Bacillus cereus Class Ib Ribonucleotide Reductase Di-iron NrdF in Complex with NrdI.
ACS Chem. Biol. (2014), 9, 526-537. [Link]