(+) or (-) strand RNA

[Synapsis]

The EK Bio book says that minus-strand RNA must be reverse transcribed first, while plus-strand RNA can be directly translated into protein. It then says retroviruses have plus-strand RNA. If retroviruses uses reverse transcriptase to reverse transcribe RNA to DNA, why would they have the type of RNA (plus-strand) that can be directly translated, rather than the type of RNA (minus-strand) that needs to be reverse transcribed first?

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[sector9]

The EK Bio book says that minus-strand RNA must be reverse transcribed first, while plus-strand RNA can be directly translated into protein. It then says retroviruses have plus-strand RNA. If retroviruses uses reverse transcriptase to reverse transcribe RNA to DNA, why would they have the type of RNA (plus-strand) that can be directly translated, rather than the type of RNA (minus-strand) that needs to be reverse transcribed first?

The bolded is wrong. In a normal virus, negative sense RNA is replicated first, becoming positive sense RNA. It is not reverse transcribed.

Your typical (+)RNA virus:

viral (+) RNA ----host ribosome translates---> protein

Your typical (-)RNA virus:

viral (-) RNA ----viral RNA-dependent RNA polymerase replicates----> (+) RNA ----host ribosome translates---> protein

For a slightly longer explanation see http://en.wikipedia.org/wiki/Sense_(molecular_biology)#RNA_sense_in_viruses

 

[Bomikepa]

do we need to know anything else about - RNA other than it must first be converted to +RNA before translation can occur?

and -RNA virus must CARRY rna- dependent rna polyermase correct?

 

[gettheleadout]

Yes, I believe the RNA-dependent RNA polymerase used is viral in origin. As a side question, EK uses the term "transcribe" to refer to the replication of negative sense RNA by RNA-dependent RNA polymerase. Is that correct usage of the term?

 

[Synapsis]

Right then, okay, I just misread it. That makes more sense. So reverse transcription and incorporation into host genome is a process distinct from this. Got it.

Yes, I believe the RNA-dependent RNA polymerase used is viral in origin. As a side question, EK uses the term "transcribe" to refer to the replication of negative sense RNA by RNA-dependent RNA polymerase. Is that correct usage of the term?

Which was my follow-up question. Anyone?

 

[sector9]

Yeah I would just call it "replication" if I had to put a name on it but it looks like virologists do use the term "transcribe" as well. You can see it used here under Class 5 which is what we're talking about http://en.wikipedia.org/wiki/Viral_replication

And yeah, the RNA-dependent RNA polymerase has to be encoded by the virus itself

 

[gettheleadout]

Yeah I would just call it "replication" if I had to put a name on it but it looks like virologists do use the term "transcribe" as well. You can see it used here under Class 5 which is what we're talking about http://en.wikipedia.org/wiki/Viral_replication

And yeah, the RNA-dependent RNA polymerase has to be encoded by the virus itself

Awesome. Thanks sector!

 

[TactFR44]

Yeah I would just call it "replication" if I had to put a name on it but it looks like virologists do use the term "transcribe" as well. You can see it used here under Class 5 which is what we're talking about http://en.wikipedia.org/wiki/Viral_replication

And yeah, the RNA-dependent RNA polymerase has to be encoded by the virus itself

Thank you this was making me frustrated. I understand that EK is like a quick breakdown but they tend to not group things well when they explain then (e.g. mutation section in chapter 2). Again, thanks for clearing this up, I was like why are they utilizing the word "transcribing" rather than "replicating" when they are referring to the synthesis of the + strand RNA from the minus strand RNA...