Section 3 Final Exam

Question 1

diff of archeal viruses (7 things)

Answer 1

1- encode pesudopeptidoglycan specific lysin enzyme
2- have NO RNA viruses isolated (but maybe identified by metagenomics)
3- have one ss DNA virus (rest are dsDNA)
4- some have circular dsDNA packed in virion (never in phages)
5- many have envelopes
6- released without lysis
7- not pathogens and extremophiles so hard to research

Question 2

When archeal viruse genomes are sequnced:

Answer 2

most have no similarity to previously discovered genes (similar to well studied phage groups)

Question 3

Model Archeal virus:

Answer 3

Sulfolobus spindle-shaped virus (SSV-1)
lemone shaped

Question 4

SSV-1 virus encodes the enzyme ________

Answer 4

reverse gyrase

Question 5

Function of SSV-1 reverse gyrase:

Answer 5

introduces positive supercoils into DNA protecting it at higher temperatures (common in hyperthermophiles)

Question 6

SSV-1 is a temperate virus:

Answer 6

1- integrates into host genome
2- gets induced for replication by UV damage or stress
3- goes through round of replication to make and release visions
4- goes back into lysogenic state

Question 7

SSV-1 type of DNA and TEMPORALLY CONTROLLED transcription:

Answer 7

Tracked expression of genes through infection of cell

dsDNA CIRCULAR (takes 6 hours to transcribe late genes)

T-ind (immediate early)
T5 and T6 (early after 1 hr)
T9 (late early 5 hrs)
Late gene after 6 HOURS

slow development when compared to other viruses (some take 5 min)

Question 8

Archeal virus circular DNA genomes can be manipulated in vitro (in a test tube and then adding that DNA back into host cell) to study the viruses replication abilities, they found that:

Answer 8

• mutation of many genes still allows for replication
• trend between conservation and essentiality, but not perfect

Question 9

Another archaeal virus :

Answer 9

Acidianus two tailed virus (ATV)
also lemon shaped

Question 10

Shape of SSV-1 capsid protein

NEVER SEEN BEFORE 1

Answer 10

4- stranded helices (4 strands of protein come together as one cable)
THEN 6 of these cables wrap around outer surface of the virion capsid and tail)

Conserved

Question 11

ATV grow tails (elongate outside of the cell when temperature is above 75 degrees)

NEVER SEEN BEFORE 2

Answer 11

Finishes growth and maturation OUTSIDE host cell

Question 12

ATV infects at ____ degrees (host optimal growth temp) and integrates into host chromosome

Answer 12

85

Question 13

if ATV infects at suboptimal temp, it leads to

Answer 13

Viral replication and lysis

Question 14

Lambda
Good conditions —-> replication and lysis
Bad conditions—–> integrate and wait
V.S
ATV
Good conditions (85 deg) —->
Bad conditions (suboptimal temp) —->

Answer 14

ATV
Good conditions —-> integrate 85 deg
Bad conditions ——-> replicate and lyse

Question 15

Another archaean virus (#3)

Answer 15

sublolobus islandicus rod-shaped virus

Question 16

sublolobus islandicus rod-shaped virus structure

Answer 16

helical shaped structures with tails at the end

Question 17

sublolobus islandicus rod-shaped virus shape UPON infection

NEVER SEEN BEFORE 3

Answer 17

viral protien makes unusual pyramid structure on cell surface which open to make holes (like a gate) that the virus is released through

Question 18

Another archaean virus (#4)

Answer 18

Acidianus filamentous virus 1 (AFV-1)

Question 19

AFV-1 structure

NEVER SEEN BEFORE 4

Answer 19

hook structure at the end of visions that claws to attach to host cells plius

Question 20

Another archaean virus (#5)

Answer 20

Sulfolobus turreted icosahedral virus (STVI)

Question 21

STVI facts to make the particle able to withstand high temp and low pH

Answer 21

• tightly packed structure
• high proline content
• increase in electrostatic interactions in capsid proteins
• increased polar surface

evolutionary adaptations

Question 22

Why do archeal cells get released without lysing cells?

Answer 22

due to cell wall structures having a wide diversity of structures (don’t have rigid peptidoglycan) so can get out by budding they don’t have to lyse

Cytoplasmic membrane
Surface layer (S-layer)
Protein sheath
glycocalyx
lipoglycan
methanochondrotin
peseudomurein

Question 23

are there RNA archeal viruses

Answer 23

metagenomic evidence:
concentrated viruses from acidic hot springs (environment dominated by arches) isolated nucleic acids and looked for high amounts of RNA
- and RT-PCR found RdRp enzyme sequences