Global regulation by CsrA in Salmonella typhimurium.
CsrA is a regulator of invasion genes in Salmonella enterica serovar Typhimurium. To investigate the wider role of CsrA in gene regulation, we compared the expression of Salmonella genes in a csrA mutant with those in the wild type using a DNA microarray. As expected, we found that expression of Salmonella pathogenicity island 1 (SPI-1) invasion genes was greatly reduced in the csrA mutant, as were genes outside the island that encode proteins translocated into eukaryotic cells by the SPI-1 type III secretion apparatus. The flagellar synthesis operons, flg and fli, were also poorly expressed, and the csrA mutant was aflagellate and non-motile. The genes of two metabolic pathways likely to be used by Salmonella in the intestinal milieu also showed reduced expression: the pdu operon for utilization of 1,2-propanediol and the eut operon for ethanolamine catabolism. Reduced expression of reporter fusions in these two operons confirmed the microarray data. Moreover, csrA was found to regulate co-ordinately the cob operon for synthesis of vitamin B12, required for the metabolism of either 1,2-propanediol or ethanolamine. Additionally, the csrA mutant poorly expressed the genes of the mal operon, required for transport and use of maltose and maltodextrins, and had reduced amounts of maltoporin, normally a dominant protein of the outer membrane. These results show that csrA controls a number of gene classes in addition to those required for invasion, some of them unique to Salmonella, and suggests a co-ordinated bacterial response to conditions that exist at the site of bacterial invasion, the intestinal tract of a host animal.
Lawhon
Sara D
SD
College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh 27606, USA.
Frye
Jonathan G
JG
Suyemoto
Mitsu
M
Porwollik
Steffen
S
McClelland
Michael
M
Altier
Craig
C
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D019856:Ethanolamine / Q000378:metabolism; D000091344:Filaggrin Proteins; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D006801:Humans; D008320:Maltose / Q000378:metabolism; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D019946:Propylene Glycol / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D014805:Vitamin B 12 / Q000096:biosynthesis
D001426:Bacterial Proteins; C093587:CsrA protein, E coli; D029968:Escherichia coli Proteins; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C419942:Spi1 protein, Salmonella; D019856:Ethanolamine; D008320:Maltose; D019946:Propylene Glycol; D014805:Vitamin B 12