THE AVIAN ADENOVIRUS PENTON - 2 FIBERS AND ONE BASE

The penton capsomer of mammalian adenoviruses consists of a trimeric, long and thin fibre inserted into a pentameric base. The avian adenovi ruses possess a penton which presents another symmetry mismatch: each pentameric base is associated with two fibres. Here we have studied th e morphology of the penton of CELO virus, an avian adenovirus, and we have determined the sequence of both fibres, one long and one short. T he short fibre is probably associated with the base in the same way as the mammalian viral fibres and we will discuss how the long fibre cou ld be attached. The shafts of all known adenovirus fibres consist of a series of 15-residue repeats. The avian virus fibres show a more comp licated and less regular shaft repeat structure with single, double an d triple repeats. The sequences of the receptor binding (head) domains of both fibres are very different from all other known fibre head dom ains and very different from each other, suggesting that the two fibre s might bind to different receptors. The genome organization of the se quenced region is rather different from that in human adenoviruses. In particular, a region homologous to the human virus E3 region was not found at the position where it normally occurs in the human virus geno me. (C) 1995 Academic Press Limited