Tissue-specific DNA binding of nuclear proteins that bind to the adenovirus inverted terminal repeat

Adenovirus (Ad) DNA replication requires nuclear factor I (NFI), a cellular sequence-specific DNA binding protein which binds to the Ad DNA inverted terminal repeat (ITR). The NFI binding consensus sequence, TGGN6-7GCCAA, possibly includes the CCAAT-box which is often observed in regulatory elements of transcription. Adjacent to the NFI binding site on the Ad ITR is the binding site for nuclear factor III (NFIII), another cellular factor that stimulates Ad DNA replication in a cell-free system. Using gel retardation assay, we have examined the tissue specificity of these DNA binding activities in mouse. High NFI activity was detected in nuclear extracts from mouse liver, kidney, and spleen. Competition gel retardation assay with double-stranded oligonucleotides containing herpes simplex virus thymidine kinase (HSV-TK) gene or hsp70 gene CCAAT-box showed no effect on mouse NFI binding to its binding site. In the course of competitive DNA-binding assay, we detected a novel DNA binding protein in mouse kidney nuclear extracts, designated nuclear factor K (NFK). The NFK binding site is included in the NFIII binding site on the Ad ITR. NFK seems to be different from NFIII, in mode of binding to its binding site.