The sequence of adenovirus fiber: similarities and differences between serotypes 2 and 5

The amino acid sequence of the fiber from adenovirus type 5 has been deduced from the nucleotide sequence of the fiber gene. This sequence is compared with that of adenovirus type 2, a closely related serotype. We find 69% homology for the fiber protein whereas the known nonstructural proteins of these two serotypes have 99% sequence homology. A detailed sequence analysis was performed in the context of the model proposed by Green et al., [(1983), EMBO J., 8, 1357–1365] for the folding of the polypeptide chain of the adenovirus type 2 fiber. The N-terminal region, which in the virion is associated with the capsid, is identical for these two serotypes. In the shaft of the fiber the features, such as periodicity of the prolines and of the hydrophobic residues in the amino acid sequence, on which the model for the adenovirus type 2 is based are very well preserved in adenovirus type 5. On the other hand, there are large differences all along the sequence of the shaft of the fiber showing that there is a very limited homology between the amino acids in the two serotypes when they do not have a key role in establishing the structure. In the knob the homology between serotypes is 64%. These results are consistent with the differences between serotypes being confined to the exposed proteins.