Differential factor binding at the promoter of early baculovirus gene PE38 during viral infection: GATA motif is recognized by an insect protein.

Regulatory elements interacting with DNA-binding proteins have been investigated in the promoter sequence of the early PE38 gene in the Autographa californica nuclear polyhedrosis virus (AcNPV). A GATA motif located 50 nucleotides upstream of the PE38 transcriptional start site is recognized differentially in the course of infection. As demonstrated by footprint and gel mobility shift assays, the GATA sequences TTATCT are protected by nuclear extracts from uninfected Spodoptera frugiperda cells and from S. frugiperda cells early postinfection (p.i.) but not by S. frugiperda cell extracts isolated 40 h p.i. We have compared the binding capacity of the insect GATA-like protein with that of the vertebrate GATA-1 factor identified as erythroid-specific factor. Our results indicate that a factor present in mouse erythroleukemia cells, presumably GATA-1, can bind to the insect GATA motif and vice versa. Evidence from transient expression studies suggests that the mutated GATA sequences do not influence PE38 promoter activity in cell culture.