Search results for "protein complexes"
showing 10 items of 113 documents
Lhca5 interaction with plant photosystem I
2006
AbstractIn the outer antenna (LHCI) of higher plant photosystem I (PSI) four abundantly expressed light-harvesting protein of photosystem I (Lhca)-type proteins are organized in two heterodimeric domains (Lhca1/Lhca4 and Lhca2/Lhca3). Our cross-linking studies on PSI-LHCI preparations from wildtype Arabidopsis and pea plants indicate an exclusive interaction of the rarely expressed Lhca5 light-harvesting protein with LHCI in the Lhca2/Lhca3-site. In PSI particles with an altered LHCI composition Lhca5 assembles in the Lhca1/Lhca4 site, partly as a homodimer. This flexibility indicates a binding-competitive model for the LHCI assembly in plants regulated by molecular interactions of the Lhca…
The non-bilayer lipid MGDG stabilizes the major light-harvesting complex (LHCII) against unfolding.
2017
Abstract In the photosynthetic apparatus of plants a high proportion of LHCII protein is needed to integrate 50% non-bilayer lipid MGDG into the lamellar thylakoid membrane, but whether and how the stability of the protein is also affected is not known. Here we use single-molecule force spectroscopy to map the stability of LHCII against mechanical unfolding along the polypeptide chain as a function of oligomerization state and lipid composition. Comparing unfolding forces between monomeric and trimeric LHCII demonstrates that the stability does not increase significantly upon trimerization but can mainly be correlated with specific contact sites between adjacent monomers. In contrast, unfol…
A Quantum Mechanic/Molecular Mechanic Study of the Wild-Type and N155S Mutant HIV-1 Integrase Complexed with Diketo Acid
2008
Integrase (IN) is one of the three human immunodeficiency virus type 1 (HIV-1) enzymes essential for effective viral replication. Recently, mutation studies have been reported that have shown that a certain degree of viral resistance to diketo acids (DKAs) appears when some amino acid residues of the IN active site are mutated. Mutations represent a fascinating experimental challenge, and we invite theoretical simulations for the disclosure of still unexplored features of enzyme reactions. The aim of this work is to understand the molecular mechanisms of HIV-1 IN drug resistance, which will be useful for designing anti-HIV inhibitors with unique resistance profiles. In this study, we use mo…
ProteoPlex: stability optimization of macromolecular complexes by sparse-matrix screening of chemical space.
2015
Molecular machines or macromolecular complexes are supramolecular assemblies of biomolecules that ensure cellular homeostasis. Structure determination of those complexes in a purified state is often a tedious undertaking due to the compositional complexity and the related relative structural instability. To improve the stability of macromolecular complexes in vitro, we present here a generic method that optimizes the stability, homogeneity and solubility of macromolecular complexes by sparse-matrix screening of their thermal unfolding behaviour in the presence of various buffers and small molecules. The method includes the automated analysis of thermal unfolding curves based on a newly deve…
β2 integrin phosphorylation on Thr758 acts as a molecular switch to regulate 14-3-3 and filamin binding
2008
AbstractLeukocyte integrins of the β2 family are essential for immune cell-cell adhesion. In activated cells, β2 integrins are phosphorylated on the cytoplasmic Thr758, leading to 14-3-3 protein recruitment to the β2 integrin. The mutation of this phosphorylation site impairs cell adhesion, actin reorganization, and cell spreading. Thr758 is contained in a Thr triplet of β2 that also mediates binding to filamin. Here, we investigated the binding of filamin, talin, and 14-3-3 proteins to phosphorylated and unphosphorylated β2 integrins by biochemical methods and x-ray crystallography. 14-3-3 proteins bound only to the phosphorylated integrin cytoplasmic peptide, with a high affinity (Kd, 261…
Site-specific incorporation of perylene into an N-terminally modified light-harvesting complex II.
2010
Employing the utility of the native chemical ligation, site-specific attachment of an ultrastable perylene dye to a derivative of the major light-harvesting complex (LHCII) was demonstrated. Biochemical analysis of the conjugate indicated that the structure and function of LHCII remain largely unaffected by the N-terminal modification.
Deregulation of the EGFR/PI3K/PTEN/Akt/mTORC1 pathway in breast cancer: possibilities for therapeutic intervention
2014
// Nicole M. Davis 1 , Melissa Sokolosky 1 , Kristin Stadelman 1 , Stephen L. Abrams 1 , Massimo Libra 2 , Saverio Candido 2 , Ferdinando Nicoletti 2 , Jerry Polesel 3 , Roberta Maestro 4 , Antonino D’Assoro 5 , Lyudmyla Drobot 6 , Dariusz Rakus 7 , Agnieszka Gizak 7 , Piotr Laidler 8 , Joanna Dulinska-Litewka 8 , Joerg Basecke 9 , Sanja Mijatovic 10 , Danijela Maksimovic-Ivanic 10 , Giuseppe Montalto 11,12 , Melchiorre Cervello 12 , Timothy L. Fitzgerald 13 , Zoya N. Demidenko 14 , Alberto M. Martelli 15 , Lucio Cocco 15 , Linda S. Steelman 1 and James A. McCubrey 1 1 Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University Greenville, NC 27858 USA 2 …
"DEVELOPMENT OF A DECISION SUPPORT SYSTEM FOR BIOINFORMATICS. EXTRACTION OF PROTEIN COMPLEXES FROM A PROTEIN-PROTEIN INTERACTION NETWORK: A CASE STUD…
2011
Decision Support Systems and Workflow Management Systems have become essential tools for some business and scientific field. This thesis propose a new hybrid architecture for problem solving expertise and decision-making process, that aims to support high-quality research in the field of bioinformatics and system biology. The first part of the dissertation introduces the project to which belong this thesis work, i.e. the “Bioinformatics Organized Resources - an Intelligent System” (BORIS) project of the ICAR-CNR; the main goal of BORIS is to provide an helpful and effective support to researchers or experimentalist, that have no familiarity with tools and techniques to solve computational p…
Htid-1, the human homolog of the Drosophila melanogaster l(2)tid tumor suppressor, defines a novel physiological role of APC.
2007
Htid-1, the human counterpart of the Drosophila tumor suppressor gene lethal(2)tumorous imaginal discs (l(2)tid) encodes three splice forms translated into three cytosolic - Tid50, Tid48 and Tid46 - and three mitochondrial - Tid43, Tid40 and Tid38 - proteins. Here we provide evidence for the association of the endogenous Tid50/Tid48 proteins with the adenomatous polyposis coli (APC) tumor suppressor in normal colon epithelium, colorectal cancer cells and mouse NIH3T3 fibroblasts. Using the Glutathione S-transferase binding assay we show that the N-terminal region including the Armadillo domain (ARM) of APC is sufficient to bind the Tid molecules. Using immunoprecipitation and confocal micro…
Recombinant water-soluble chlorophyll protein from Brassica oleracea var. Botrys binds various chlorophyll derivatives.
2003
A gene coding for water-soluble chlorophyll-binding protein (WSCP) from Brassica oleracea var. Botrys has been used to express the protein, extended by a hexahistidyl tag, in Escherichia coli. The protein has been refolded in vitro to study its pigment binding behavior. Recombinant WSCP was found to bind two chlorophylls (Chls) per tetrameric protein complex but no carotenoids in accordance with previous observations with the native protein [Satoh, H., Nakayama, K., Okada, M. (1998) J. Biol. Chem. 273, 30568-30575]. WSCP binds Chl a, Chl b, bacteriochlorophyll a, and the Zn derivative of Chl a but not pheophytin a, indicating that the central metal ion in Chl is essential for binding. WSCP …