XXXX SspA is a transcription activator for @entity10483 late genes.

@entity72242 @entity10483 @entity526
The stringent starvation protein A (SspA), an @entity526 RNA polymerase (RNAP)-associated protein, has been reported to be essential for lytic growth of @entity10483 . Unlike P1 early promoters, P1 late promoters are not recognized by RNAP alone. A phage-encoded early protein, @entity72242 ( @entity72242 , formerly called gp10), has been shown to be required for P1 late transcription in vivo. Here, we demonstrate that SspA is a transcription activator for P1 late genes. Our results indicated that @entity72242 is not limiting in an sspA mutant. However, the transcription of P1 late genes was deficient in an sspA mutant in vivo. We demonstrated that SspA/ @entity72242 are required for transcription activation of the P1 late promoter Ps in vitro. In addition, SspA and @entity72242 were shown to facilitate the binding of RNAP to Ps late promoter DNA. Activation of late transcription by SspA/ @entity72242 was dependent on holoenzyme containing sigma70 but not sigmaS, indicating that the two activators discriminate between the two forms of the holoenzyme. Furthermore, P1 early gene expression was downregulated in the wild-type background, whereas it persisted in the sspA mutant background, indicating that SspA/ @entity72242 mediate the transcriptional switch from the early to the late genes during P1 lytic growth. Thus, this work provides the first evidence for a function of the @entity526 RNAP-associated protein SspA.
