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To obtain molecular insights into these cellular processes, we use X-ray crystallography in combination with other biophysical and biochemical methods.
 
Although all muscles use actin and myosin for contraction, only in skeletal and cardiac muscle are these proteins organized into sarcomeres, which are the fundamental contractile units of striated muscle. The Z-disc is the boundary of individual sarcomeres where thin filaments are anchored, and plays central and unique role as the main anchoring point of the molecular machinery that underlies muscle contraction. The most striking feature of muscle and Z-disc proteins in particular, is the high frequency of multiple protein-protein interactions that form part of a complex network.

Although all muscles use actin and myosin for contraction, only in skeletal and cardiac muscle are these proteins organized into sarcomeres, which are the fundamental contractile units of stri¬ated muscle. The Z-disc is the boundary of individual sarcomeres where thin filaments are anchored, and plays central and unique role as the main anchoring point of the molecular machinery that underlies muscle contraction. The Z-disc represents a highly organized three-dimensional structure containing several proteins assembled in multi-protein complexes, many of them centered on alpha-actinin. alpha-actinin confers both stability and plasticity to a variety of actin-based arrays. In muscle cells it is a major component of the Z-disk, where it cross-links actin filaments and serves as a versatile platform for multiple protein-protein interactions. alpha-actinin binds the amino terminal end of the giant protein titin as well as to a plethora of Z-band proteins including myotilin, telethonin, MLP, FATZ and cypher/ZASP. Myotilin, MLP, FATZ, and ZASP bind alpha-actinin and telethonin binds titin and FATZ, which in turn binds also to gamma-filamin.

The aim of our research is to generate detailed structural information on the protein-protein interaction network in the stri¬ated muscle Z-disk, starting from its important component alpha-actinin and moving towards mac¬romolecular complexes to shed light on both functional and structural implications of these interactions.

In order to define stable constructs and high affinity complexes yeast two-hybrid screens, co-im¬munoprecipitation, co-affinity purification and limited proteolysis will be used.

The principal experimental technique employed is macromolecular crystallography, in combination with biophysical and biochemical techniques. Complementary structural biology methods - NMR, FRET, electron microscopy, mass-spectrometry, circular dichroism, and small angle X-ray scattering, together with structural bioinformatics methods for structural analysis and validation are available in the Department, on the Campus or via collaborations and are recruited to enrich the structural information.