My main research interests revolve around understanding complex biological systems at the molecular and atomic level. In my laboratory we study the structure and function of protein biomolecules in an effort to understand their role, as well as the role of their disease-causing variants (such as rare mutations or single nucleotide polymorphisms), in the pathogenesis, predisposition and diagnosis of human disease. We furthermore aim to validate and complement existing genetic or clinical association studies by providing mechanism-based insight that can establish the diagnostic and prognostic value of protein biomarkers for human diseases. We are also involved in rational-drug design efforts focused on the protein molecules we are currently investigating. We guide and support these efforts by providing structural and mechanistic insight as well as developing and performing customised in vitro and cell-based assays.

EXPERIMENTAL APPROACHES
We utilize a variety of biochemical approaches in an effort to unravel the molecular-level or atomic-level mechanisms that underlie protein function in health and disease. These approaches include:

  Recombinant protein expression in bacterial, insect and mammalian cell lines (small and medium scale)
  Protein purification and characterization (FPLC, SDS-PAGE etc)
  Gene cloning and expression vector construction
  Biophysical and structural analysis of proteins
  Enzymology and assay development
  Proteomics and peptide sequencing
  Specialized cell-based assays

Current research projects:
ER AMINOPEPTIDASES AND THE IMMUNE RESPONSE
The adaptive immune response relies on the presentation of small peptide-antigen fragments onto specialised cell-surface receptors (MHC molecules) for recognition by cytotoxic T-lymphocytes (for more information click here). These peptides are generated from the degradation of intra or extra cellular proteins. Intracellular aminopeptidases like ERAP1, ERAP2 and IRAP play a crucial role in antigenic peptide generation and affect quantitative and qualitative aspects of the immune response (for more information click here, also read this paper and this paper).
Naturally occurring polymorphisms (SNPs) on ERAP1/2 have been linked with predisposition to autoimmune diseases like Ankylosing Spondylitis and Diabetes as well as susceptibility to viral and bacterial infections and tumour development. How ERAP1 SNPs affect disease predisposition and pathogenesis in not known, but it has been hypothesised that aberrant antigen presentation may be the mechanism behind these effects. We are currently evaluating the diagnostic and prognostic value of these SNPs by studying their effects on protein function and antigen processing. We are also developing small molecular-weight inhibitors for these molecules in an effort to control their enzymatic activity in vivo for immunotherapy applications.

HUMAN APOLIPOPROTEINS AND DISEASE
Apolipoprotein E (apoE) is an important protein of the lipid transport system that has an indisputable role in atherosclerosis, dyslipidemia, and Alzheimer's disease (AD) (for more information on apolipoproteins click here). The apoE4 isoform is a major genetic risk factor for AD with 40% of all patients having at least one apoE4 allele. ApoE4 is susceptible to proteolysis in the brain and apoE4 N-terminal fragments have been found in the brain of AD patients. It is possible that the presence of some of these fragments are of significant prognostic value for the development of AD. ApoE4 displays significant structural plasticity and undergoes dramatic conformational changes upon binding lipids.
In a recent study we discovered that fragments of apoE4 are actually more stable than the wild-type protein and therefore lack the necessary conformational plasticity for function. Our results also suggest a complex but labile tertiary structural organization within the C-terminal moiety of apoE4 that may be important for its physiological function. Alterations of the structure of apoE4 brought forth by truncations may be responsible for the abnormal apoE4 functionality observed in Alzheimer disease patients brain (Biochemistry, 2008). A specific fragment of apoE4 has been recently discovered to be able to promote the internalisation of ABeta42 peptide (the principle component of amyloid plaques that are found in the brain of AD patients) into neuronal cells. This finding provides a possible link between two early molecular events in AD pathogenesis, namely apoE4 proteolysis and Abeta42 presence in neuronal cells (J. Neurochem., 2010).

More details on ongoing research projects can be found below: