Furthermore, the presence
of the SP1 tail enhances the mobility of several preceding residues
and, possibly, of CypA loop as well. (These findings have been corroborated
by our most recent dynamics studies using heteronuclear
dipolar lineshapes, which will be reported in a forthcoming
manuscript.) Thus, conformational plasticity in functionally important
loop residues of CA and CA-SP1 is induced by primary
sequence. Our results support the hypothesis that SP1 cleavage
induces the disassembly of immature CA and subsequent reassembly
into the mature capsid core.