biostudies-literatureHan YNIBIB NIH HHSNCRR NIH HHSNIGMS NIH HHS17793-803https://www.ebi.ac.uk/biostudies/studies/S-EPMC3928671biostudies-literatureUnknown135(47)A key stage in HIV-1 maturation toward an infectious virion requires sequential proteolytic cleavage of the Gag polyprotein leading to the formation of a conical capsid core that encloses the viral RNA genome and a small complement of proteins. The final step of this process involves severing the SP1 peptide from the CA-SP1 maturation intermediate, which triggers the condensation of the CA protein into the capsid shell. The details of the overall mechanism, including the conformation of the SP1 peptide in CA-SP1, are still under intense debate. In this report, we examine tubular assemblies of CA and the CA-SP1 maturation intermediate using magic angle spinning (MAS) NMR spectroscopy. At magnetic fields of 19.9 T and above, outstanding quality 2D and 3D MAS NMR spectra were obtained for tubular CA and CA-SP1 assemblies, permitting resonance assignments for subsequent detailed structural characterization. Dipolar- and scalar-based correlation experiments unequivocally indicate that SP1 peptide is in a random coil conformation and mobile in the assembled CA-SP1. Analysis of two CA protein sequence variants reveals that, unexpectedly, the conformations of the SP1 tail, the functionally important CypA loop, and the loop preceding helix 8 are modulated by residue variations at distal sites. These findings provide support for the role of SP1 as a trigger of the disassembly of the immature CA capsid for its subsequent de novo reassembly into mature cores and establish the importance of sequence-dependent conformational plasticity in CA assembly.Journal of the American Chemical SocietyMagic angle spinning NMR reveals sequence-dependent structural plasticity, dynamics, and the spacer peptide 1 conformation in HIV-1 capsid protein assemblies.PMC3928671P41EB002026P30 GM110758P20 RR015588P41 EB002026P50 GM082251P20RR015588-10P50GM082251-03Gronenborn AMBurton SPolenova THan YGor'kov PLBrey WHung ISuiter CLByeon IJAhn JLipton ASGan ZRice DHou GfalseMagic angle spinning NMR reveals sequence-dependent structural plasticity, dynamics, and the spacer peptide 1 conformation in HIV-1 capsid protein assemblies.A key stage in HIV-1 maturation toward an infectious virion requires sequential proteolytic cleavage of the Gag polyprotein leading to the formation of a conical capsid core that encloses the viral RNA genome and a small complement of proteins. The final step of this process involves severing the SP1 peptide from the CA-SP1 maturation intermediate, which triggers the condensation of the CA protein into the capsid shell. The details of the overall mechanism, including the conformation of the SP1 peptide in CA-SP1, are still under intense debate. In this report, we examine tubular assemblies of CA and the CA-SP1 maturation intermediate using magic angle spinning (MAS) NMR spectroscopy. At magnetic fields of 19.9 T and above, outstanding quality 2D and 3D MAS NMR spectra were obtained for tubular CA and CA-SP1 assemblies, permitting resonance assignments for subsequent detailed structural characterization. Dipolar- and scalar-based correlation experiments unequivocally indicate that SP1 peptide is in a random coil conformation and mobile in the assembled CA-SP1. Analysis of two CA protein sequence variants reveals that, unexpectedly, the conformations of the SP1 tail, the functionally important CypA loop, and the loop preceding helix 8 are modulated by residue variations at distal sites. These findings provide support for the role of SP1 as a trigger of the disassembly of the immature CA capsid for its subsequent de novo reassembly into mature cores and establish the importance of sequence-dependent conformational plasticity in CA assembly.2013-01-01T00:00:00Z2013 Nov2020-11-19T14:43:55Z2019-03-26T23:30:09ZS-EPMC39286712416464610.1021/ja406907h