Figure 11.

Serine 13 is not required for the kinase activity of UL97 but contributes to the protein stability of UL97 during HCMV infection.A, serum-starved hTERT-BJ1 fibroblasts were mock infected (M) or infected with the indicated recombinant viruses at an MOI of 1. Lysates prepared at the indicated day post-infection (dpi) were analyzed by Western blotting with the indicated antibodies. B, analysis as in panel (A) except at an MOI of 0.1. For all panels, representative images from one of three independent biological replicates are shown. The mock-infected serum-starved cells were incubated in 0.1% FBS for 48 h (serum starvation) and then cells were stimulated by 15% FBS for 18 h (15% FBS). C, the protein levels of HA-tagged UL97 from the experiment shown in panel (A) were quantified and normalized to GAPDH levels. The values of HA-tagged UL97-S13A (white bars) are presented relative to the values of HA-tagged WT UL97 (gray bars: set at 1). Error bars denote SDs from three biological replicates. D, analysis as in panel (C) except from the experiment in panel (B). Statistical analysis utilized a two-tailed unpaired Student’s t test. ∗∗p < 0.01; ∗p < 0.05; n.s., not significant (p > 0.05). FBS, fetal bovine serum; MOI, multiplicity of infection.