Capsid Organization

• View of electron density map at one of the 420 isopeptide bonds.There is con-tinuous electron density for the Lys169-Asn356 isopeptide bond.

• The amino group of Lys169 side chain rects with the g carbon of the Asn356 amide group to form an isopeptide bond between the side chains.

• The Glu363 carboxyl from a third subunit is hydrogen-bondd to the carbonyl oxygen of the isopeptide.

• Three subunit are requred:Asn356 from one subunit, Lys169 from another, and the catalytic residue Glu363 from a third subunit.