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

TITLE=Cysteine-Mediated Gene Expression and Characterization of the CmbR Regulon in Streptococcus pneumoniae

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01929

DOI=10.3389/fmicb.2016.01929

ISSN=1664-302X

ABSTRACT=<p>In this study, we investigated the transcriptomic response of <italic>Streptococcus pneumoniae</italic> D39 to cysteine. Transcriptome comparison of the D39 wild-type grown at a restricted concentration of cysteine (0.03 mM) to one grown at a high concentration of cysteine (50 mM) in chemically-defined medium (CDM) revealed elevated expression of various genes/operons, i.e., <italic>spd-0150</italic>, <italic>metQ</italic>, <italic>spd-0431</italic>, <italic>metEF</italic>, <italic>gshT</italic>, <italic>spd-0618</italic>, <italic>fhs, tcyB</italic>, <italic>metB</italic>-<italic>csd</italic>, <italic>metA</italic>, <italic>spd-1898</italic>, <italic>yvdE</italic>, and <italic>cysK</italic>, likely to be involved in the transport and utilization of cysteine and/or methionine. Microarray-based data were further confirmed by quantitative RT-PCR. Promoter <italic>lacZ</italic>-fusion studies and quantitative RT-PCR data showed that the transcriptional regulator CmbR acts as a transcriptional repressor of <italic>spd-0150</italic>, <italic>metEF</italic>, <italic>gshT</italic>, <italic>spd-0618</italic>, <italic>tcyB</italic>, <italic>metA</italic>, and <italic>yvdE</italic>, putatively involved in cysteine uptake and utilization. The operator site of CmbR in the promoter regions of CmbR-regulated genes is predicted and confirmed by mutating or deleting CmbR operator sites from the promoter regions of these genes.</p>