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Viral Enzymes

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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Viral Enzymes

Postby SysBio » Tue May 26, 2009 7:36 am

(I posted this in the Cell Biology forum but did not get a response, so I am re-posting this here )

For the viruses that must carry a specific enzyme (eg. viruses with ssDNA, -ssRNA genomes):

1. It is carried in the capsid AND coded for in their genomes, right?

2. since they need this enzyme before they can use their genome, how do they ensure that a lot is transcribed?

Thanks in advance...
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Re: Viral Enzymes

Postby biohazard » Wed May 27, 2009 6:46 am

Umm, not sure I got your question right, but viruses use the host cell's synthesis machinery to produce all the enzymes they need, including the ones that are required for the conversion of their genome (e.g. reverse transcriptase for RNA viruses). These are then packed into the viral particle during the viral assembly.

So, because they already carry the enzyme within the capsid, it is ready to use when the virus offloads its "cargo" into their target cell. In the cell, all parts of the virus are then produced again and assembled into a functional virus, including fresh copies of the enzyme(s) they need.

Naturally many viral particles are produced that are inactive because the assembly has failed, for example if some of the required enzymes did not get loaded into the capsid. Depending of the virus type, inactive viruses may constitute several percents of the total number of viral particles.
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Re: Viral Enzymes

Postby sara135 » Tue Jul 12, 2011 12:17 pm

A virus uses several tools to infect a cell. Enzymes are such tools, helping the virus progress through the various stages of infection. Enzyme inhibitors can block the action of these viral enzymes, interrupting the spread of disease at a particular point.
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