Viruses of Thermophilic Organisms

1. Viruses of Thermophilic Organisms Vrushali Bhoraj & Jon Cruz

2. Extremophiles • These are organisms that thrive in extreme conditions they include: • Thermophiles • Halophiles • Barophiles • Acidophiles • Xerophiles • Many thermophiles inhabit areas of multiple extremes and some are methanogenic (produce methane)

3. Thermophiles and Hyperthermophiles • Thermophiles are organisms that have optimum growth temperatures of 45oC - 80oC (113o F - 176o F) • Hyperthermophiles are organisms that have an optimum growth temperature above 80oC (176o F)

4. Thermophilic Environments • Environments that foster the growth of thermophiles and hyperthermophiles include hot springs, deep-sea hydrothermal vents, areas associated with volcanic phenomena, hot water heaters, and even surfaces of compost heaps

5. Energy Generation • These organisms tend to be either chemoorganotrophs or chemolithotrophs • Example of chemolithotrophic energy generation include iron oxidation and elemental sulfur (S0) reduction

6. DNA Stability • Many of these organisms use large concentrations of compatible solutes to increase the temperature at which their DNA denatures • Whereas the DNA of most organisms is negatively supercoiled, the DNA of these organisms is positively supercoiled

7. Positive Supercoiling • Thermophiles and Hyperthermophiles use a unique enzyme called reverse gyrase to introduce positive supercoils into their DNA • This stabilizes the DNA and increases its melting temperature

8. Protein Stability • Thermophiles and Hyperthermophiles use unique heat active chaperonins to refold partially denatured proteins • Many proteins of these organisms contain a very hydrophobic core and a greater extent of disulfide bonds and ionic interactions which increases the temperature at which the proteins denature • Taq polymerase is an important enzyme from these microbes isolated from Thermus aquaticus

9. Unusual Membranes • Archaeal hyperthermophiles have cellular membranes lacking fatty acids • They have a lipid monolayer composed of C40 (biphytanyl) linked to glycerol by an ether, not an ester, linkage

10. Extremophile Viruses Viruses of Halobacteria & Methanobacteria • Most viruses have classic head and tail morphology • Most are grouped under the Myoviridae and the Siphoviridae families of viruses (some exceptions) • 12 different types have been isolated so far

11. Viruses of Thermophiles: Unusual Viruses • The viruses of thermophiles and hyperthermophiles are as unique as their hosts • Some of these viruses possess bottle-shaped or lemon-shaped virions • Others have the ability to undergo certain morphological developments outside of a host cell A)Lipothrix Virus SIFV B)Lipothrix Virus AFV 1 C)Rudivirus SIRV1 D)Fusellovirus SSV1 E)Guttavirus SNDV

12. Acidianus bottle-shaped virus (ABV) • Double stranded DNA virus with a linear genome of 24 kb • Infects archaea of the genus Acidianus • Has a bottle-shaped virion with a funnel-shaped core • The narrow end is important for DNA transfer to the host cell • The wide end possesses a ring of filaments the function of which is not clearly understood

13. Sulfolobus: A Thermoacidophile • Several different viruses infect the thermoacidophile sulfolobus among these are: • Fuselloviridae: SSV1 (Japan) SSV2 and SSV3 (Iceland) • Rudiviridae: SIRV1 and SIRV2 (Iceland) • Lipothrixviridae: SIFV • Alphalipothrixvirus: Thermoproteus virus 1 • Betalipothrixvirus: Sulfolobus mislandicus filamentous virus • Gammalipothrixvirus: Acidianous filamentous virus 1 • Guttaviridae: SNDV (Sulfolobus neozealandicus)

14. Information on Sulfolobus Viruses Fuselloviridae -60 x 90 nm spindle shaped virions -Circular dsDNA 15.5 kb -35 ORF’s -Lysogenic propagation Rudiviridae -Stiff 23 x 800-900 helical rods -Linear dsDNA with covalently closed ends -45 ORF’s

15. More Sulfolobus Viruses Lipothrixviridae -24 x 250 nm flexible rods with attachment fibers -Linear dsDNA 43 kb -74 ORF’s Guttaviridae -Droplet Shaped -Circular and highly modified genome -dsDNA 20 kb

16. Relationship of these Virus Isolates • Comparisons of previous and recent isolates in order to determine phylogenetic and evolutionary relationships

17. Comparison of Isolate Genomes

18. Acidianus two-tailed virus (ATV) • This virus also has an interesting virion that is lemon-shaped • It infects the archaeon Acidianus convivator • This virus is found in hot-springs which reach temperatures between 85-93o C with a pH of about 1.5

19. Development Outside of Hosts • It has been shown that this virus is able to develop one long tail on each end of its virion in the absence of host cells • If this virus is incubated at natural temperatures in the absence of hosts, about half the population develops the tails within a week • Since this is one of the few viruses of hyperthermophiles which causes lysis, it is thought that the development of the tail aids in stabilizing the virion and infecting a new host in harsh conditions with low host concentrations

20. Extracellular Development From Häring M, Vestergaard G, et. al. 2005. Virology: independent virus development outside a host. Nature 436 (7054): 1101-2.

21. RM378 • Infects Rhodothermus marinus, a type of thermoacidophile • Myoviridae, A2 morphology (includes the T4 bacteriophage of E. coli) • Shows some sequence homology to T4 bacteriophage • Elongated head 95 x 85 nm and a 150 nm long tail with a connector • Infectious up to 65 C, optimum temperature is 64 C • 130 kb dsDNA with 200+ ORF’s and a 42% G+C content • Thermostable RNA ligase 1 has been isolated • Advantages: RLM-RACE, other RNA-DNA ligation applications of biotechnology

22. Virus-Like Particles (VLP’s) • His1, lytic viral isolate of Haloarcula hispanica • Linear dsDNA14.9 kb • Was first isolated from Methanococcus voltae strain A3 • 23 kb covalently closed circular DNA • Pav1, a deep-sea isolate of Pyrococcus Abysii • Circular dsDNA 17.5 kb

23. References • Bath C and Dyall-Smith ML. 1998. His1, an archaeal virus of the Fuselloviridae family that infect Haloacula hispanica. Journal of Virology 72(11): 9392-5. • Beeby M, O’Connor BD, et al. 2005. The genomics of disulfide bonding and protein stabilization in thermophiles. DOI: 10.1371/journal.pbio..0030309. • Bettstetter M, Peng X, et. al. 2003. AFV1, a novel virus infecting hyperthermophilic archaea of the genus acidianus. Virology 215 (1): 68-80. • Brock, T.D., M. T. Madigan, J.M. Martinko, and J. Parker. 2006. Biology of Microorganisms, 11th edition. Prentice Hall, Upper Saddle River, NJ. • Geslin C, Romancer M, et. al. 2004. PAV1 the first virus-like particle isolated from a hyperthermophilic Euryarchaote, Pyrococcus abysii. Journal of Virology (78)4: 1954-61. • Häring M, Reinhard R, et. al. 2005. Viral diversity in hot springs of Pozzuoli, Italy, and characterization of a unique archaeal virus, Acidianus Bottle-Shaped Virus, from a new family, the Ampullaviridae. Journal of Virology 79 (15): 9904-12.

24. References Continued • Häring M, Vestergaard G, et. al. 2005. Virology: independent virus development outside a host. Nature 436 (7054): 1101-2. • Rice G, et al. 2001. The structure of a thermophilic archaeal virus shows a double-stranded DNA viral capsid type that spans all domains of life. Proceedings of the National Academy of Sciences of the United States of America 98(23): 13341-5. • Robb FT. 2004. Genomics of thermophiles. In: Fraser CM, Read TD, Nelson KE. Microbial Genomes. Totawa, NJ: Humana Press. p. 245-267. • Staley, J.T., and A. Reysenbach. 2002. Biodiversity of Microbial Life. John Wiley & Sons, Inc., New York. • Thorarinn B, Hjorleifsdottir SH, et. al. 2003. Discovery and characterization of a thermostable bacteriophage RNA ligase to T4 RNA ligase 1. Nucleic Acids Research 31(24): 7247-54. • Wiedenheft B, et. al. 2004. Comparative genomic analysis of hyperthermophilic archaeal Fuselloviridae viruses.” Journal of Virology 78(4):1954-61.

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