An SP1-binding site and TATA element are sufficient to support full transactivation by proximally bound NS1 protein of minute virus of mice

The minute virus of mice (MVM) P38 Sp1-binding site and TATA box, inserted in an otherwise heterologous plasmid background, could be transactivated to high levels by the MVM NS1 protein targeted proximally to these sequences, demonstrating that these core promoter regulatory elements are sufficient to support essentially wild-type levels of NS1-transactivated expression and suggesting that NS1 may act directly or indirectly with Sp1 and or elements of the general transcription machinery. Accordingly, we show that bacterially generated NS1 can interact strongly, independent of nucleic acid bridging, and most likely directly with Sp1 in vitro and can associate, in a nucleic acid-independent manner, with endogenous Sp1 as it exists in a complex transcriptionally active murine nuclear extract. NS1 achieves the same fold activation of an isolated TATA element over its low basal level and can also be demonstrated to interact efficiently and specifically with the general transcription factors TBP and TFIIA (alpha, beta) in vitro. (C) 1998 Academic Press.