Role for the L1-52/55K protein in the serotype specificity of adenovirus DNA packaging

Abstract

The packaging of adenovirus (Ad) DNA into virions is dependent upon cis-acting sequences and trans-acting proteins. We studied the involvement of Ad packaging proteins in the serotype specificity of packaging. Both Ad5 and Ad17 IVa2 and L4-22K proteins complemented the growth of Ad5 IVa2 and L4-22K mutant viruses, respectively. In contrast, the Ad5 L1-52/55K protein complemented an Ad5 L1-52/55K mutant virus, but the Ad17 L1-52/55K protein did not. The analysis of chimeric proteins demonstrated that the N-terminal half of the Ad5 L1-52/55K protein mediated this function. Finally, we demonstrate that the L4-33K and L4-22K proteins have distinct functions during infection.

FIG. 1.

Western blot analysis of Ad5 and Ad17 L1 52/55K proteins. N52.E6 cells were infected with wild-type Ad5 or Ad17 (200 particles/cell) or mock infected (lanes 1 to 3, respectively) and were untransfected (−) or transfected with pcDNA3, pcDNA3 plus Ad5-L1, or pcDNA3 plus Ad17-L1 (lanes 4 to 8), without (lane 4) or with (lanes 5 to 8) cotransfection of pTG3602-pm8001, as indicated above the lanes. Molecular weight markers are indicated on the left.

FIG. 2.

Ad5 and Ad17 L1-52/55K proteins. (A) An alignment (CLUSTAL-N) of the Ad5 and Ad17 L1-52/55K proteins is shown. Asterisks indicate sequence identity, and one- and two-dot symbols indicate sequence similarity. The arrows above the amino acid sequence indicate the sites of the junctions of the Ad5/17 chimeric proteins. (B) Schematic diagram of the Ad5/Ad17 L1-52/55K chimeric proteins. Ad5 sequences are indicated with solid lines; Ad17 sequences are indicated with hatched lines. Amino acid numbers of the chimeric proteins are given above the lines. (C) Western blot analysis of Ad5/17 chimeric proteins. N52.E6 cells were cotransfected with pTG3602-pm8001 and expression vectors for wild-type Ad5 and Ad17 L1-52/55K proteins or Ad5/17 chimeric proteins (lanes 1 to 5). Molecular weight markers are indicated to the left and adjacent to lane 5.