title: The steady-state orgA specific mRNA levels in Salmonella enterica serovar Typhimurium are repressed by oxygen during logarithmic growth phase but not early-stationary phase.
abstract: The orgA gene from Salmonella enterica serovar Typhimurium is involved in promoting cellular invasion of the pathogen. Its exact role in virulence is still unclear mainly due to difficulties in understanding its complex regulation. In this study a novel competitive RT-PCR (cRT-PCR) system was developed to measure the steady-state orgA specific mRNA levels in cells under various growth parameters. Previous studies have been inconsistent regarding oxygen regulation of orgA. Using our system we found that oxygen repressed the copy levels 3.5-fold in cells grown only to logarithmic phase. Oxygen repression was not observed in cells grown to early-stationary phase, a parameter that has previously been demonstrated to be the most invasive stage of growth. The importance of NaCl in orgA gene regulation is also illustrated. Significant increases in copy numbers were observed after growth in high NaCl conditions. Measuring the steady-state mRNA levels using cRT-PCR provides an accurate insight into prokaryotic gene regulation prior to translation.
authors.affiliation: School of Biological and Environmental Sciences, Faculty of Life and Health Sciences, University of Ulster, Coleraine, Co. Londonderry, Northern Ireland BT52 1SA, UK. dean.russell@ucd.ie
authors.forename: Dean A
authors.initials: DA
authors.lastname: Russell
authors.forename: James S
authors.initials: JS
authors.lastname: Dooley
authors.forename: Richard W
authors.initials: RW
authors.lastname: Haylock
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D010100:Oxygen / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C088960:OrgA protein, Salmonella typhimurium; D012333:RNA, Messenger; D037521:Virulence Factors; D010100:Oxygen