Lysine post-translational modifications and the cytoskeleton.

PTMs (post-translational modifications) of lysine residues have proven to be major regulators of gene expression, protein-protein interactions, and protein processing and degradation. This is of particular importance in regulating the cytoskeleton, an enormously complex system of proteins responsible for cell motility, intracellular trafficking, and maintenance of cell form and structure. The cytoskeleton is present in all cells, including eukaryotes and prokaryotes, and comprises structures such as flagella, cilia and lamellipodia which play critical roles in intracellular transport and cellular division. Cytoskeletal regulation relies on numerous multi-component assemblies. In this chapter, we focus on the regulation of the cytoskeleton by means of PTMs of lysine residues on the cytoskeletal subunits and their accessory proteins. We specifically address the three main classes of cytoskeletal proteins in eukaryotes that polymerize into filaments, including microfilaments (actin filaments), intermediate filaments and microtubules. We discuss the identification and biological importance of lysine acetylation, a regulator of all three filament types. We also review additional lysine modifications, such as ubiquitination and SUMOylation, and their role in protein regulation and processing.