host machinery needed to virion assembly (4)
cellular chaperons
transport systems
secretory pathways
nuclear import and export machinery
where do viral proteins congregate
internal membranes
virion assembly steps (3)
sub-assemblies
self assembly
scaffolds
strategies to make sub assemblies (3)
assembly from individual protein molecules
assembly from a poly protein precursor
chaperone assisted assembly
whats a sub assembly
Partially assembled structure of a virus - they serve as building blocks
methods of capsid and nucleocapsid assembly (2)
self assembly
viral scaffolding protein: chaperons for assembly
3 viral components that regulate self assembly of capsid and nucleocapsid assembly
nucleic acid binding
membrane binding
protein cleavage
are chaperones for assembly part of the mature virion
no - they get degraded once a genome gets in
does genome binding enhance assembly
yes
what binds the envelope
nucleocapsids
sequential assembly step (4)
individual proteins
structural unit: sub assemblies
hire order structures if needed
virion
incorporation of viral nucleic acids into a virion is called
packaging
concerted assembly
the viral structural units assemble only in associated with the genomic nucleic acid
sequential assembly
the nucleic acids are inserted into the pre formed protein shell
whats required for sequential assembly (2)
virion must have a mechanism to insert nucleic acids
virion must maintain an open portal of entry
what drives concerted nucleocapsid assembly
the nucleocapsid because they all assemble at the same time
how is a RNA or DNA recognized as viral instead of cellular
they have packaging signals specific to the viral genome
when recognizing DNA for assembly, what is usually recognized
sequences
when recognizing RNA for assembly, what is usually recognized
structures
where are packaging signals on the genome
on the ends
DNA concatemers
Long continuous DNA molecules containing multiple genome copies linked end-to-end
packaging on genome concatemers
terminase recognizes the signal sequence to let in into a capsid and then terminase cuts it at the next signal to feed the next one into a new capsid
RNA packaging signals are what
usually structures
what is required for RNA packaging for signals
the (trident) sequence ad sequences in the 5’ TAR and 5” poly A
