@article {505, title = {Deciphering Mode of Action of Functionally Important Regions in the Intrinsically Disordered Paxillin (Residues 1-313) Using Its Interaction with FAT (Focal Adhesion Targeting Domain of Focal Adhesion Kinase). [Protein Technology Core]}, journal = {PLoS One}, volume = {11}, year = {2016}, month = {2016}, pages = {e0150153}, abstract = {

Intrinsically disordered proteins (IDPs) play a major role in various cellular functions ranging from transcription to cell migration. Mutations/modifications in such IDPs are shown to be associated with various diseases. Current strategies to study the mode of action and regulatory mechanisms of disordered proteins at the structural level are time consuming and challenging. Therefore, using simple and swift strategies for identifying functionally important regions in unstructured segments and understanding their underlying mechanisms is critical for many applications. Here we propose a simple strategy that employs dissection of human paxillin (residues 1-313) that comprises intrinsically disordered regions, followed by its interaction study using FAT (Focal adhesion targeting domain of focal adhesion kinase) as its binding partner to retrace structural behavior. Our findings show that the paxillin interaction with FAT exhibits a masking and unmasking effect by a putative intra-molecular regulatory region. This phenomenon suggests how cancer associated mutations in paxillin affect its interactions with Focal Adhesion Kinase (FAK). The strategy could be used to decipher the mode of regulations and identify functionally relevant constructs for other studies.

}, keywords = {Focal Adhesion Protein-Tyrosine Kinases, Focal Adhesions, Humans, Intrinsically Disordered Proteins, Models, Molecular, Paxillin, Peptide Fragments, Protein Binding, Protein Structure, Tertiary}, issn = {1932-6203}, doi = {10.1371/journal.pone.0150153}, author = {Neerathilingam, Muniasamy and Bairy, Sneha G and Mysore, Sumukh} } @article {507, title = {Tailor-made ezrin actin binding domain to probe its interaction with actin in-vitro. [Protein Technology Core]}, journal = {PLoS One}, volume = {10}, year = {2015}, month = {2015}, pages = {e0123428}, abstract = {

Ezrin, a member of the ERM (Ezrin/Radixin/Moesin) protein family, is an Actin-plasma membrane linker protein mediating cellular integrity and function. In-vivo study of such interactions is a complex task due to the presence of a large number of endogenous binding partners for both Ezrin and Actin. Further, C-terminal actin binding capacity of the full length Ezrin is naturally shielded by its N-terminal, and only rendered active in the presence of Phosphatidylinositol bisphosphate (PIP2) or phosphorylation at the C-terminal threonine. Here, we demonstrate a strategy for the design, expression and purification of constructs, combining the Ezrin C-terminal actin binding domain, with functional elements such as fusion tags and fluorescence tags to facilitate purification and fluorescence microscopy based studies. For the first time, internal His tag was employed for purification of Ezrin actin binding domain based on in-silico modeling. The functionality (Ezrin-actin interaction) of these constructs was successfully demonstrated by using Total Internal Reflection Fluorescence Microscopy. This design can be extended to other members of the ERM family as well.

}, keywords = {Actins, Animals, Avian Proteins, Chickens, Cytoskeletal Proteins, In Vitro Techniques, Microfilament Proteins, Models, Molecular, Protein Interaction Domains and Motifs, Recombinant Fusion Proteins}, issn = {1932-6203}, doi = {10.1371/journal.pone.0123428}, author = {Shrivastava, Rohini and K{\"o}ster, Darius and Kalme, Sheetal and Mayor, Satyajit and Neerathilingam, Muniasamy} } @article {718, title = {Development of the structural core and of conformational heterogeneity during the conversion of oligomers of the mouse prion protein to worm-like amyloid fibrils.}, journal = {J Mol Biol}, volume = {423}, year = {2012}, month = {2012 Oct 19}, pages = {217-31}, abstract = {

Understanding how structure develops during the course of amyloid fibril formation by the prion protein is important for understanding prion diseases. Determining how conformational heterogeneity manifests itself in the fibrillar and pre-fibrillar amyloid aggregates is critical for understanding prion strain phenotypes. In this study, the formation of worm-like amyloid fibrils by the mouse prion protein has been characterized structurally by hydrogen-deuterium exchange coupled to mass spectrometry. The structural cores of these fibrils and of the oligomer on the direct pathway of amyloid fibril formation have been defined, showing how structure develops during fibril formation. The structural core of the oligomer not on the direct pathway has also been defined, allowing the delineation of the structural features that make this off-pathway oligomer incompetent to directly form fibrils. Sequence segments that exhibit multiple local conformations in the three amyloid aggregates have been identified, and the development of structural heterogeneity during fibril formation has been characterized. It is shown that conformational heterogeneity is not restricted to only the C-terminal domain region, which forms the structural core of the aggregates; it manifests itself in the N-terminal domain of the protein as well. Importantly, all three amyloid aggregates are shown to be capable of disrupting lipid membrane structure, pointing to a mechanism by which they may be toxic.

}, keywords = {Amino Acid Sequence, Amyloid, Animals, Deuterium Exchange Measurement, Kinetics, Mice, Models, Molecular, Molecular Sequence Data, Prion Proteins, Prions, Protein Conformation, Protein Folding}, issn = {1089-8638}, doi = {10.1016/j.jmb.2012.06.040}, author = {Singh, Jogender and Sabareesan, A T and Mathew, M K and Udgaonkar, Jayant B} } @article {712, title = {An inhibitor of nonhomologous end-joining abrogates double-strand break repair and impedes cancer progression.}, journal = {Cell}, volume = {151}, year = {2012}, month = {2012 Dec 21}, pages = {1474-87}, abstract = {

DNA Ligase IV is responsible for sealing of double-strand breaks (DSBs) during nonhomologous end-joining (NHEJ). Inhibiting Ligase IV could result in amassing of DSBs, thereby serving as a strategy toward treatment of cancer. Here, we identify a molecule, SCR7 that inhibits joining of DSBs in cell-free repair system. SCR7 blocks Ligase IV-mediated joining by interfering with its DNA binding but not that of T4 DNA Ligase or Ligase I. SCR7 inhibits NHEJ in a Ligase IV-dependent manner within cells,\ and activates the intrinsic apoptotic pathway. More importantly, SCR7 impedes tumor progression in mouse models and when coadministered with DSB-inducing therapeutic modalities enhances their sensitivity significantly. This inhibitor to target NHEJ offers a strategy toward the treatment of cancer and improvement of existing regimens.

}, keywords = {Amino Acid Sequence, Animals, Cell Line, Tumor, Disease Models, Animal, DNA Breaks, Double-Stranded, DNA End-Joining Repair, DNA Ligase ATP, DNA Ligases, Drug Design, Drug Resistance, Neoplasm, Humans, Lymphocytes, Lymphoma, Male, Mice, Mice, Inbred BALB C, Mice, Nude, Models, Molecular, Molecular Sequence Data, Neoplasms, Protein Structure, Tertiary, Pyrimidines, Radiation Tolerance, Rats, Schiff Bases, Sequence Alignment}, issn = {1097-4172}, doi = {10.1016/j.cell.2012.11.054}, author = {Srivastava, Mrinal and Nambiar, Mridula and Sharma, Sheetal and Karki, Subhas S and Goldsmith, G and Hegde, Mahesh and Kumar, Sujeet and Pandey, Monica and Singh, Ram K and Ray, Pritha and Natarajan, Renuka and Kelkar, Madhura and De, Abhijit and Choudhary, Bibha and Raghavan, Sathees C} }