Mammalian reovirus L2 gene and lambda 2 core spike protein sequences and whole-genome comparisons of reoviruses type 1 Lang, type 2 Jones, and type 3Dearing

The reovirus L2 genome segment encodes the core spike protein lambda2, whic h mediates enzymatic reactions in 5' capping of the viral plus-strand trans cripts. Complete nucleotide-sequence determinations were made for the L2 ge nome segments of eight mammalian reoviruses, including the prototype isolat es of serotypes 1 and 2: Lang (T1L) and Jones (T2J), respectively. Each L2 segment was found to be 3912 or 3915 bases in length. Partial nucleotide-se quence determinations were also made for the 3916-base L2 segment of reovir us type 3 Dearing (T3D), the prototype isolate of serotype 3. The whole-gen ome sequence of reovirus T3D was reported previously. The T1L L2 analysis r epresents completion of the whole-genome sequence of that isolate as well. The T2J L2 analysis leaves only the sequence of the M1 segment yet to be re ported from the genome of that isolate. The T2J M1 sequence made available from analysis in another lab was used for initiating whole-genome compariso ns of reoviruses T1L, T2J, and T3D in this report. The nine L2 gene sequenc es and deduced lambda2 protein sequences were used to gain further insights into the biological variability, structure, and functions of lambda2 throu gh comparisons of the sequences and reference to the crystal structure of c ore-bound lambda2. Phylogenetic comparisons suggest the presence of three e volutionary lines of divergent L2 alleles among the nine isolates. Localize d regions of conserved amino acids in the lambda2 crystal structure include active-site clefts of the RNA capping enzyme domains, sites of interaction s between,2 domains within the pentameric spike structure, and sites of int eraction between lambda2 subunits and other proteins in viral particles. (C ) 2001 Academic Press.