Dataset Information

Structural basis for lipid binding and function by an evolutionally conserved protein, Serum Amyloid A

ABSTRACT: Serum amyloid A (SAA) is a plasma protein that transports lipids during inflammation. To explore SAA solution conformations and lipid binding mechanism, we used hydrogen-deuterium exchange mass spectrometry, lipoprotein reconstitution, sequence analysis and molecular dynamics simulations. Solution conformations of lipid-bound and lipid-free mSAA1 at pH~7 agreed in details with the crystal structures but also showed important differences. The results revealed that amphipathic α-helices h1 and h3 comprise a lipid-binding site that is partially pre-formed in solution, is stabilized on lipoproteins, and shows lipid-induced folding of h3. This site sequesters apolar ligands via a concave hydrophobic surface in SAA oligomers. The largely disordered C-terminal region is conjectured to mediate promiscuous binding of other ligands. The h1-h2 linker region forms an unexpected β-hairpin that may represent an early amyloidogenic intermediate. The results establish structural underpinnings for understanding SAA interactions with lipids and other ligands, its evolutional conservation, and its transition to amyloid.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Mus Musculus (mouse)

SUBMITTER: John R. Engen

LAB HEAD: John R. Engen

PROVIDER: PXD016391 | Pride | 2020-02-17

REPOSITORIES: Pride

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Structural Basis for Lipid Binding and Function by an Evolutionarily Conserved Protein, Serum Amyloid A.

Frame Nicholas M NM Kumanan Meera M Wales Thomas E TE Bandara Asanga A Fändrich Marcus M Straub John E JE Engen John R JR Gursky Olga O

Journal of molecular biology 20200206 7

Serum amyloid A (SAA) is a plasma protein that transports lipids during inflammation. To explore SAA solution conformations and lipid-binding mechanism, we used hydrogen-deuterium exchange mass spectrometry, lipoprotein reconstitution, amino acid sequence analysis, and molecular dynamics simulations. Solution conformations of lipid-bound and lipid-free mSAA1 at pH~7.4 agreed in details with the crystal structures but also showed important differences. The results revealed that amphipathic α-heli ...[more]

PMID: 32035904

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Project description:Src family kinases are often overexpressed and constitutively active in cancer cells, where they represent promising targets for therapeutic intervention. In myeloid hematopoietic cells, Hck, Lyn, and Fgr are associated with both chronic and acute forms of myeloid leukemia. All three of these kinases are expressed in acute myeloid leukemia (AML), where high-level expression correlates with poor survival. The pyrrolopyrimidine Src-family kinase inhibitor A-419259 (also known as RK-20449) has been shown to significantly inhibit patient-derived AML bone marrow cell growth in immunocompromised mice. Recent work has identified an N-phenylbenzamide kinase inhibitor, known as TL02-59, which potently inhibited Fgr kinase activity in vitro and reversed orthotopic engraftment of AML cells in the bone marrow and spleen of immunocompromised mice following oral administration. The inhibitory mechanism of this compound with Fgr or other Src-family members has not been reported. Both wild-type Fgr and a tail mutant (i.e., replacement of Tyr527 with Phe) were shown to produce equal numbers of transformed colonies when expressed in rodent fibroblasts, whereas wild-type Hck transforming activity was completely repressed. In both Hck and Fgr, however, the tail tyrosine residue was shown to be phosphorylated, and hydrogen deuterium exchange mass spectrometry (HDX MS) of near-full-length Fgr was consistent with the closed conformation in solution, with the SH3 domain bound to the SH2-kinase linker and the tail bound to SH2. Here we present the first X-ray crystal structures of near-full-length Fgr bound to the ATP site inhibitors A-419259 and TL02-59. Structural changes induced by the inhibitors in the crystalline state were validated in solution using HDX MS, with A-419259 stabilizing the closed conformation and TL02-59 enhancing exposure of the SH3 domain to solvent. These new structures help to explain the constitutive activity of wild-type Fgr in cells as well as its unique sensitivity to TL02-59, which is currently in development for AML and other maladies.

Dataset Information

Structural basis for lipid binding and function by an evolutionally conserved protein, Serum Amyloid A

Publications

Structural Basis for Lipid Binding and Function by an Evolutionarily Conserved Protein, Serum Amyloid A.

Similar Datasets

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