Einführung in die Biophysik! Viren!!! Joachim Rädler! 25 Juli 2011!! Schwerpunktstudium " Biophysik! LMU!

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1 Einführung in die Biophysik! LMU! Schwerpunktstudium " Biophysik! Joachim Rädler! 25 Juli 2011!! Viren!!!

2 Viren - Ein Beispiel für geordnete (quasikristalline) biologische Überstrukturen! Die einzelnen Virustypen unterscheiden sich in der Art der Nukleinsäure, der Hüllenstruktur, dem Mechanismus des Eindringens und der Art, wie die Nukleinsäure repliziert wird.!

3 The coats of viruses.! These electron micrographs of negatively stained virus particles are all at the same scale. (A) Bacteriophage T4, a large DNAcontaining virus that infects E. coli. The DNA is stored in the bacteriophage head and injected into the bacterium through the cylindrical tail. (B) Potato virus X, a filamentous plant virus that contains an RNA genome. (C) Adenovirus, a DNA-containing virus that can infect human cells. The protein capsid forms the outer surface of this virus. (D) Influenza virus, a large RNAcontaining animal virus whose protein capsid is further enclosed in a lipid-bilayer-based envelope containing protruding spikes of viral glycoprotein.!

4 Negativ Staining EM revolutionized structural research on viruses! Ebola Virus! Entero Virus! Papillo Virus! Ebola virus image by Dr. Frederick A. Murphy, University of California, Davis

5 The simplest of all viral life cycles. The hypothetical virus shown consists of a small double-stranded DNA molecule that codes for only a single viral capsid protein. No known virus is this simple.!

6 The life cycle of the Semliki forest virus. " The virus parasitizes the host cell for most of its biosyntheses.!

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8 Two enveloped viruses that bud from different domains of the plasma membrane. Electron micrographs showing that one type of enveloped virus buds from the apical plasma membrane while another type buds from the basolateral plasma membrane of the same epithelial cell line grown in culture. These cells grow with their basal surface attached to the culture dish. The boxed area in each schematic drawing corresponds to the indicated electron micrograph.! Rädler/ SS 2006! BPE 4.5! 8!

9 Schematic drawings of several types of viral genomes. The smallest viruses contain only a few genes and can have an RNA or a DNA genome; the largest viruses contain hundreds of genes and have a double-stranded DNA genome. Some examples of these types of viruses are as follows: single-stranded RNAtobacco mosaic virus, bacteriophage R17, poliovirus; doublestranded RNAreovirus; single-stranded DNA-parvovirus; single-stranded circular DNAM13 and fx174 bacteriophages; double-stranded circular DNASV40 and polyomaviruses; doublestranded DNAT4 bacteriophage, herpes virus; double-stranded DNA with covalently linked terminal proteinadenovirus; double-stranded DNA with covalently sealed endspoxvirus. The peculiar ends (as well as the circular forms) overcome the difficulty of replicating the last few nucleotides Rädler/ at SS the 2006! end of a DNA chain (see pp. BPE ! and 364).! 9!

10 The life cycle of a retrovirus.! The retrovirus genome consists of an RNA molecule of about 8500 nucleotides; two such molecules are packaged into each viral particle. The enzyme reverse transcriptase first makes a DNA copy of the viral RNA molecule and then a second DNA strand, generating a double-stranded DNA copy of the RNA genome. The integration of this DNA double helix into the host chromosome, catalyzed by the viral integrase, is required for the synthesis of new viral RNA molecules by the host-cell RNA polymerase.!

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12 Transposon! Ein Transposon ist ein bewegliches genetische Element welches innerhalb des Wirtschromosoms seinen Platz wechseln kann. Einige Transposons können sich dabei auch vermehren.!! Sie gelten als älteste Vorläufer von Viren.!

13 The T4 bacteriophage chromosome, showing the positions of the more than 30 genes involved in T4 DNA replication. The genome of bacteriophage T4 consists of 169,000 nucleotide pairs and encodes about 300 different proteins.!

14 #Replicative transposition! In the course of replicative transposition, the DNA sequence of the transposon is copied by DNA replication. The end products are a DNA molecule that is identical to the original donor and a target DNA molecule that has a transposon inserted into it. In general, a particular DNA-only transposon moves either by the cut-and-paste pathway shown in Figure 5-70 or by the replicative pathway outlined here. However, the two mechanisms have many enzymatic similarities, and a few transposons can move by either pathway.!

15 Adenovirus!

16 virus nuclear import and export!

17 Adenovirus!

18 The capsids of some viruses, all shown at the same scale. (A) Tomato bushy stunt virus; (B) poliovirus; (C)simian virus 40 (SV40); (D) satellite tobacco necrosis virus. The structures of all of these capsids have been determined by x- ray crystallography and are known in atomic detail.!

19 Die 5 Platonischen Körper! Gekappt! E - K + F = 2 (Eulersche Regel)!! E: Ecken! K: Kanten! F: Flächen!

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21 Äquivalenzprinzip: Jedes Protomere sieht die gleiche Umgebung! F E A D C B A D O E F B C M N

22 Deltaeder:" Polyeder, die aus gleichförmigen Dreiecken bestehen!

23 Quasi-Äquivalenz! Jedes der gleichseitigen Dreiecke des Icosaeders kann in f 2 Unterdreiecke aufgeteilt werden, wenn die Dreiecksseiten in f gleiche Teile zerlegt werden.! T = Pf 2 : die Anzahl Unterdreiecke! P = h 2 +hk+k 2 mit h,k: beliebige ganze Zahlen, also! P = 1, 3, 7, 13, 19, 21, 31, und f = 1, 2, 3, 4,...! Die Zahl der Untereinheiten pro Dreieck ist drei, damit ist die Gesamtzahl der Untereinheiten:! Z = 3 20 T = 60 T!

24 Wie die EM-Aufnahmen zeigen, beobachtet man Aggregate von Untereinheiten (Proteinen) mit fünffacher und mit sechsfacher Symmetrieachse, sogenannte Pentamere und Hexamere. Diese morphologischen Untereinheiten bezeichnet man hier als Capsomere, wogegen der einzelne Protein-Baustein als Protomeres bezeichnet wird.! Pentamer Hexamer Z: Anzahl äquivalenten Untereinheiten : Protomere!

25 Protomere Untereinheiten des Adenovirus! Hexon Peripentonales Hexon Penton Base Nadel Adenovirus, Typ 5:!P = 1, T = 25, T C = 252, Z =!1500! 240 Hexons, 12 Pentons!

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27 Tabak Mosaik Virus (TMV)!

28 Strukturdaten des intakten TMV!! " Länge: 3000 Å; Innendurchmesser: 40 Å; Außendurchmesser: 180 Å! Molekulargewicht: 4 * 10 7 " Ganghöhe der helikal aufgebauten Proteinhülle: 23 Å! Zahl der Protein-Untereinheiten pro Windung: 16.34" Gesamtzahl der Protein-Untereinheiten: 2130" Anzahl der Nucleotide: pro Untereinheit ca. 3; insgesamt 6.340" Molekulargewicht der Protein-Untereinheiten: 16500" Anzahl der Aminosäuren pro Protein-Untereinheit: 158!

29 Molekulare Struktur des TMV!

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31 TMV!

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34 Bacterial Viruses = Phages

35 The T4 bacteriophage chromosome, showing the positions of the more than 30 genes involved in T4 DNA replication. The genome of bacteriophage T4 consists of 169,000 nucleotide pairs and encodes about 300 different proteins.!

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37 T4 phage injecting DNA into liposomes! full empty experiments at Curie Institute

38 INTEGRATION VON! LAMBDA IN DAS! WIRTSGENOM!