The major late transcription factor binds to and activates the mouse metallothionein I promoter.

Human (HeLa) cells contain a protein, MLTF, which specifically binds to a DNA sequence in the adenovirus 2 major late promoter and activates transcription of that promoter. The presence of MLTF in uninfected cells suggests that this factor contributes to the transcription of some cellular genes. We find that MLTF binds in a sequence-specific manner to the 5'-flanking region of the mouse metallothionein I (mMTI) gene. Binding was localized between -101 and -94 (relative to the initiation site at +1) by DNA-binding gel electrophoresis assay and DNA methylation interference analysis. As in adenovirus, binding occurred in a region containing the sequence CPuCGTGAC. Deletion of this sequence both eliminated the binding of MLTF and produced a fourfold reduction in transcriptional efficiency in vitro. In contrast to the intact promoter, transcription from the deletion mutant promoter was not stimulated by addition of purified MLTF to an in vitro reconstituted reaction. These results suggest that MLTF contributes to the transcription of cellular genes.