ABSTRACT
Earlier studies have shown that cdc2 kinase is activated during herpes simplex virus 1 infection and that its activity is enhanced late in infection even though the levels of cyclin A and B are decreased below levels of detection. Furthermore, activation of cdc2 requires the presence of infected cell protein no. 22 and the UL13 protein kinase, the same gene products required for optimal expression of a subset of late genes exemplified by US11, UL38, and UL41. The possibility that the activation of cdc2 and expression of this subset may be connected emerged from the observation that dominant negative cdc2 specifically blocked the expression of US11 protein in cells infected and expressing dominant negative cdc2. Here we report that in the course of searching for a putative cognate partner for cdc2 that may have replaced cyclins A and B, we noted that the DNA polymerase processivity factor encoded by the UL42 gene contains a degenerate cyclin box and has been reported to be structurally related to proliferating cell nuclear antigen, which also binds cdk2. Consistent with this finding, we report that (i) UL42 is able to physically interact with cdc2 at both the amino-terminal and carboxyl-terminal domains, (ii) the carboxyl-terminal domain of UL42 can be phosphorylated by cdc2, (iii) immunoprecipitates obtained with anti UL42 antibody contained a roscovitine-sensitive kinase activity, (iv) kinase activity associated with UL42 could be immunodepleted by antibody to cdc2, and (v) UL42 transfected into cells associates with a nocodazole-enhanced kinase. We conclude that UL42 can associate with cdc2 and that the kinase activity has the characteristic traits of cdc2 kinase.
Partial deduced sequence of the 110-kD-calmodulin complex of the avian intestinal microvillus shows that this mechanoenzyme is a member of the myosin I family.
