Sequence characterization of the adenovirus 40 fiber gene

The fiber gene of human adenovirus type 40 has been characterized. The 6.1-kbp EcoRI fragment C of the Ad40 genome, from map units 74 through 92, was cloned and the right-most 2.8 kbp from 84 map units was sequenced. By analogy with Ad2, this region would be expected to contain the gene specifying the Ad40 fiber polypeptide. Sequencing revealed an open reading frame of 1641 bases on the r-strand, the first 53 bases of which had marked homology with the corresponding L5 (fiber) regions of Ad2 (77.2%), Ad5 (75.0%), and Ad3 (64.3%). In addition, base positions 1114 to 1146 of this open reading frame had 85% homology with base positions 1198 to 1230 of the Ad2 fiber gene. The predicted polypeptide sequence of 547 amino acids showed marked homology with the Ad2, Ad5, and Ad3 fiber polypeptides in two regions, in the first 55 amino acids from the N-terminus and from amino acids 372 through 382. Analysis of hydrophobic amino acid positions revealed a repeating pattern of approximately 15 residues between positions 42 and 374, with 21 repeats. The sequence of the Ad40 polypeptide thus fits the model of Green et al. [1983), EMBO J. 2, 1357-1365) for the structure of the adenovirus fiber, but is 35 amino acids shorter than the Ad2 fiber polypeptide, with one less 15-residue repeat in the shaft region. According to this model, the regions of highest homology between the Ad40 fiber polypeptide and those of Ad2, Ad5, and Ad3 correspond to the tail of the shaft and the base of the knob. The results of this analysis are in agreement with previously published EM data on the fiber length of subgroup F adenoviruses.