Structure and function of protein complexes in biological systems
Figure 1: DAPK-CaM complex. Colour codes: DAPK, green; CaM, red. (de Diego et al., 2010)
Figure 2: AGT-(Pex5p)2-AGT complex. Colour codes: AGT, yellow, orange; Pex5p, cyan, magenta. (Fodor et al., 2012)
The Wilmanns group investigates a variety of protein-ligand complexes within the context of biological systems, employing a broad range of molecular and structural biology techniques.
The architecture of the protein interactome in sarcomeric muscle cells: Many proteins found in muscle cells, when dysfunctional, are associated with cardiovascular diseases. We investigate how large protein filament systems forming the overall architecture of ‘sarcomeric units’ in muscle cells – such as actin, myosin, nebulin, titin, myomesin and obscurin – are connected and interact with each other, frequently mediated via small scaffold proteins. We have determined the structure and function of some key complexes, including telethonin-mediated assembly of the N-terminus of titin (Zou et al., 2006) and the overall architecture of the elastic filament protein myomesin (Pinotsis et al., 2008; Pinotsis et al., 2012). Our future focus will be on novel protein interactions within the sarcomeric Z-disk and M-line region, and novel signalling functions of the protein partners involved.
Activity regulation in protein kinases: The human kinome – the part of the genome that expresses protein kinases – comprises about 600 genes. About 70 protein kinases share a common C-terminal autoregulatory domain. To investigate the mechanism of activity regulation in these kinases, we first determined the structure of the kinase domain from the giant filament protein titin, in the inhibited apo-conformation (Mayans et al., 1998). More recently, we have unravelled the structure of the apoptotic Death Associated Protein Kinase-1, in the presence of the regulatory scaffold calcium/calmodulin (CaM) (figure 1). This structure provides insight into how CaM binding leads to kinase activation by withdrawing the autoregulatory domain from the kinase active site. Our goal is to complement ongoing structural studies by in vitro and in vivo functional studies, to decipher underlying, general molecular mechanisms that regulate the activity of members of the CaM-dependent protein kinase family and, ultimately, to promote drug discovery against those kinases involved in cancer formation and progression.
The architecture of the translocon of peroxisomes: Peroxisomes are cell organelles that allow sequestered metabolic processes that would interfere with other processes in the cytosol. Proteins involved in these processes are generally translocated as active and folded targets. For the first time, we have unravelled the mechanism involved in the recognition of peroxisome protein targets by the peroxisome import receptor Pex5p, by determining the structure of the cargo-binding domain of the receptor in the absence and presence of the cargo protein sterol carrier protein 2 (Stanley et al., 2006) and alanine-glyoxylate aminotransferase (figure 2). Our goal, with support of two national and international research networks, is to provide insight into the overall architecture of the peroxisomal translocon, using a broad range of structural biology and imaging methods, complemented by genetic and cell biology-oriented approaches.
Structural systems biology in M. tuberculosis: We have determined the X-ray structures of a number of protein targets, some of them of known function and others unknown. For instance, we were able to identity Rv2217 as a novel cysteine/lysine dyad acyltransferase, which allows activation of several important protein complexes by lipoylation (Ma et al., 2006). Using available structural data and with support of European research network systeMTb, we aim to use systems biology-orientated approaches (such as proteomics, metabolomics, lipidomics and transcriptomics) to investigate functional processes in living mycobacteria, with the aim of making data available to promote the development of new drugs, vaccines and diagnostic markers.