Month: September 2022

OTHER COMMON STRUCTURES. "Viruses using the HK97-fold share unexpected similarities beyond the fold of their coat proteins including the architecture of their virions, an internal scaffolding (or Δ-domain) protein-mediated assembly, active dsDNA packaging, and capsid maturation events." (dsDNA = double stranded DNA). http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

PENTON AND HEXON SUBUNITS. "In capsids, HK97-like coat protein subunits are organized into pentons and hexons. An exception would be for capsids with a triangulation (T) number of 1, which would be composed entirely of pentons." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

DRAMATIC CAPACITY. "The versatility of the HK97-fold is also evident when comparing the diameters of capsids with confirmed HK97-like coat proteins, which range from ~24 nm to ~185 nm. This fold evolved to accommodate these dramatic differences in capsid diameter and the varying degrees of capsid curvature accompanying the spectrum of diameters." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

CAPSID ASSEMBLY. "Bacteriophage P22 provides a well-studied example for assembly of capsids formed from subunits with the HK97-fold. Assembly of bacteriophage P22 in vivo proceeds via a nucleation-limited reaction in which 415 copies of coat protein (gp5, the product of gene 5) co-polymerize with 60–300 scaffolding proteins (gp8), the dodecameric portal protein complex (gp1), and ejection proteins (gp7, gp16 and gp20)." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

PROCAPSID EMERGENCE. "Coat protein monomers are added to the growing edge, eventually producing a closed, spherical, precursor structure (“procapsid”) in which the coat proteins are organized with T=7 laevo quasi-symmetry. During assembly scaffolding protein catalyzes, stabilizes, and directs geometry of the procapsid." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

CAPSID MATURATION. "Considerable conformational rearrangements of coat protein N-arm, E-loop, and A-domain occur upon maturation. In P22 coat protein, the β-hinge has been shown to be the most dynamic region of the subunit during capsid maturation." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

CAPSID β-HINGE OF P22. "This hinge appears to direct motion of the A-domain during hexon symmetrization that occurs simultaneously with expansion. Finally, plug proteins (gp4, gp10 and gp26) close the portal protein channel and tailspike proteins (gp9) are added to complete the mature infectious phage." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

LATE FUNCTIONAL MODIFICATIONS. "In addition to the canonical HK97-like core, many coat proteins contain additional accessory domains or extended loops, likely imparting specific functions." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

VERSATILE LEGO. "For most capsids with HK97-like coat proteins, chemically identical subunits occupy non-identical sites in the icosahedron. This relies on coat protein plasticity as well as a mechanism by which identical subunits can be “switched” into slightly different conformations required to occupy quasi-equivalent sites in the icosahedron, a process known as conformational switching." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn

FLEXIBILITY VERSUS STABILITY. "Conformational flexibility is also necessary for the rearrangements during the capsid maturation process. Thus, a fine balance is necessitated between this conformational polymorphism and stability of monomeric coat proteins." http://www.sciencedirect.com/science/article/pii/S0042682215001920 View in LinkedIn