THE TRANSCRIPTIONAL REGULATOR YY1 BINDS TO THE 5'-TERMINAL REGION OF B19 PARVOVIRUS AND REGULATES P6 PROMOTER ACTIVITY

We performed a systematic study to identify cellular factors that boun d to the terminal repeat region of B19 parvovirus. Using electrophoret ic mobility shift assays; we detected one cellular factor which promin ently bound to the repeat region. The factor was purified from K562 nu clear extract by specific DNA affinity column chromatography and ident ified as YY1, a multifunctional transcription factor. Of multiple poss ible YY1 binding sites in the upstream region of the P6 promotes, thre e showed specific strong binding. Transcription enhancement by YY1 was demonstrated in vitro by transient transfection assays. In studies us ing truncated and mutated versions of this region, YY1 activity was di minished by the alteration of any two of these three sites and abolish ed by the alteration of all three sites. Our results suggest that YY1 is a positive regulator of B19 parvovirus transcription.