AUTHOR=Afzal Muhammad , Shafeeq Sulman , Kuipers Oscar P. 

TITLE=Ascorbic acid-dependent gene expression in Streptococcus pneumoniae and the activator function of the transcriptional regulator UlaR2

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00072

DOI=10.3389/fmicb.2015.00072

ISSN=1664-302X

ABSTRACT=<p>In this study, we have explored the impact of ascorbic acid on the transcriptome of <italic>Streptococcus pneumoniae</italic> D39. The expression of several genes and operons, including the <italic>ula</italic> operon (which has been previously shown to be involved in ascorbic acid utilization), the AdcR regulon (which has been previously shown to be involved in zinc transport and virulence) and a PTS operon (which we denote here as <italic>ula2</italic> operon) were altered in the presence of ascorbic acid. The <italic>ula2</italic> operon consists of five genes, including the transcriptional activator <italic>ulaR2</italic>. Our β-galactosidase assay data and transcriptome comparison of the <italic>ulaR2</italic> mutant with the wild-type demonstrated that the transcriptional activator UlaR2 in the presence of ascorbic acid activates the expression of the <italic>ula2</italic> operon. We further predict a 16-bp regulatory site (5′-ATATTGTGCTCAAATA-3′) for UlaR2 in the P<italic>ula2</italic>. Furthermore, we have explored the effect of ascorbic acid on the expression of the AdcR regulon. Our ICP-MS analysis showed that addition of ascorbic acid to the medium causes zinc starvation in the cell which leads to the activation of the AdcR regulon.</p>