β-helix

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Frost protection protein from Choristoneura fumiferana
Antifreeze protein from Tenebrio molitor

The β-helix is a secondary structure of proteins .

properties

As a protein structure, a β-helix consists of several parallel β-strands in a helical arrangement. The β-helix has two, three or four outer surfaces. Proteins with a pentapeptide repeat have four outer surfaces. Because of the repeated β strands, the amino acid sequence is often repetitive. The β-helix is stabilized by hydrogen bonds between the β-strands, partly also by ionic bonds and protein-protein interactions . Examples of proteins with right-handed β-helices are pectate lyase from Aspergillus niger , the tailspike protein of bacteriophage P22, rhamnogalacturonase A from Aspergillus aculeatus and an antifreeze protein from Tenebrio molitor . Examples of proteins with left-handed β-helices are an antifreeze protein from Choristoneura fumiferana , UDP-N-acetylglucosamine acyltransferase and an archaic carbonic anhydrase . For some, a chaperone is necessary for correct folding , of which two types have been described so far. The β strands of a β helix are relatively short and straight, so the β sheets do not have the usual right-handed curvature. In the Ramachandran plot , the peptide bonds are in a narrower range than common β-sheets.

β-helices in amyloidoses

β-helix of the tau protein from the neurofibrillar bundles of an Alzheimer's patient (PDB code 5o3t).

β-helices are formed by refolding other protein structures in a number of protein folding diseases, the amyloidoses . These include the central nervous system , the Alzheimer's disease ( tau protein and amyloid precursor protein APP), the Parkinson's disease ( synuclein ), and Huntington's disease ( huntingtin ) and the prion diseases while. Outside the CNS, amyloid is found, for example, in Ostertag amyloidoses ( lysozyme , apolipoprotein A1 , fibrinogen A or transthyretin ). Bence Jones protein is an immunoglobulin light chain that is formed in plasma cells in monoclonal disease and the precipitation of which causes kidney failure. Amylin overproduction and precipitation as amyloid destroys the β-cells of the pancreas and causes the secondary insulin dependence in patients with diabetes II . In dialysis patients, β-microglobulin amyloidosis can occur if the protein is not removed using special membranes.

literature

  • A. Mitraki, S. Miller, MJ van Raaij: Review: conformation and folding of novel beta-structural elements in viral fiber proteins: the triple beta-spiral and triple beta-helix. In: Journal of structural biology. Volume 137, Numbers 1-2, 2002 Jan-Feb, pp 236-247, doi : 10.1006 / jsbi.2002.4447 , PMID 12064949 .
  • IJ Clifton, MA McDonough, D. Ehrismann, NJ Kershaw, N. Granatino, CJ Schofield: Structural studies on 2-oxoglutarate oxygenases and related double-stranded beta-helix fold proteins. In: Journal of inorganic biochemistry. Volume 100, Number 4, April 2006, pp. 644-669, doi : 10.1016 / j.jinorgbio.2006.01.024 , PMID 16513174 .

Individual evidence

  1. ↑ MW vetting, SS Hegde, Fajardo JE, A. Fiser, SL Roderick, HE Takiff, JS Blanchard: Pentapeptide repeat proteins. In: Biochemistry. Volume 45, number 1, January 2006, pp. 1-10, doi : 10.1021 / bi052130w , PMID 16388575 , PMC 2566302 (free full text).
  2. ↑ J. Jenkins, O. Mayans, R. Pickersgill: Structure and evolution of parallel beta-helix proteins. In: Journal of structural biology. Vol. 122, number 1-2, 1998, pp. 236-246, doi : 10.1006 / jsbi.1998.3985 , PMID 9724625 .
  3. ↑ YC Liou, A. Tocilj, PL Davies, Z. Jia: Mimicry of ice structure by surface hydroxyls and water of a beta-helix antifreeze protein. In: Nature. Volume 406, Number 6793, July 2000, pp. 322-324, doi : 10.1038 / 35018604 , PMID 10917536 .
  4. ↑ EK Leinala, PL Davies, Z. Jia: Crystal structure of beta-helical antifreeze protein points to a general ice binding model. In: Structure (London, England: 1993). Volume 10, Number 5, May 2002, pp. 619-627, PMID 12015145 .
  5. ↑ C. Kisker, H. Schindelin, BE Alber, JG Ferry, DC Rees: A left-hand beta-helix revealed by the crystal structure of a carbonic anhydrase from the archaeon Methanosarcina thermophila. In: The EMBO journal. Volume 15, Number 10, May 1996, pp. 2323-2330, PMID 8665839 , PMC 450161 (free full text).
  6. ↑ EC Schulz, R. Ficner: Knitting and snipping: chaperones in β-helix folding. In: Current opinion in structural biology. Volume 21, Number 2, April 2011, pp. 232-239, doi : 10.1016 / j.sbi.2011.01.009 , PMID 21330133 .
  7. ↑ Engelbert Buxbaum: Protein Folding Diseases . In: Fundamentals of Protein Structure and Function . Springer, Cham, 2015, ISBN 978-3-319-19919-1 , pp. 203–224 , doi : 10.1007 / 978-3-319-19920-7_10 ( springer.com [accessed October 31, 2017]).