User:Marion Wehrung/Sandbox

Fusion proteins (also called chimeric proteins) are proteins created by joining two genes that coded for separated proteins. Translation of this fusion gene lead to formation of new polypeptide with functional properties derived from original proteins. Alpha-synuclein fused to maltose-binding protein is a fusion protein.

Alpha-synuclein is an abundant protein in human brain and to a lesser extent in muscles, heart and other tissues. It plays an important role in presynaptic terminals found in neurons and can interact with phospholipids and proteins. Studies have shown that a bad folding of this protein could lead to the formation of insoluble fibrils and thereby be a cause of Parkinson’s disease. Maltose-binding protein is find in bacteria. The fusion protein allows to see the structure of alpha-synuclein and to study it by X-rays.

Alpha-synuclein

Structural informations

Alpha-synuclein is a 140 amino acids of about 14 kDa protein encoded by the SNCA gene. It does not have a defined structure but it can form α-helical structures by binding to phospholipids for example and β-sheet structure. It is composed of three distinct regions. The first is the amino terminus (residues 1 to 60) which is lysine-rich and modulates its interactions with membranes. It contains apolipoproteins lipid-binding motifs which allow to form α-helical structures on membrane binding. It is composed of four repeated domains (20-30, 31-41, 42-56, 57-67) which look like following : [EGS]-KT—K-[EQ]-[GQ]-V-X. The central region contains a hydrophobic motif from residue 61 to 95 known as the non-amyloid-β component involved in the protein aggregation, it confers the β-sheet potential. Finally, an acidic carboxy-terminal domain, rich in proline and highly negatively charged, which is implicated in regulating its nuclear localization and interactions with small molecules, other proteins and metals and which seems to be unstructured.

Synucleins are small soluble proteins. Below there is the adopted 3D structure which an unstable monomer.

Protein function

Aggregation and propagation

Maltose-binding protein

Structural informations

Protein function

Applications

Fused protein