Furthermore, fifty-five out of the 147 ArcA-activated genes (37%), and 100 out of the 245 ArcA-repressed genes (41%) contained at least one putative ArcA-binding site (Additional file 1: Table

S1). Figure 2 Logo of the information matrix obtained from the alignment of ArcA sequences for S . Typhimurium. Sequences were obtained by searching the S. Typhimurium LT2 genome [Accession #: AE006468 (chromosome) and AE606471 (plasmid)] with known ArcA sequences derived from the corresponding ArcA-regulated genes in E. coli. A total of 20 E. coli sequences were used to obtain the logo shown. The total height of each column of characters represents the amount of information [measured in bits, which is the maximum entropy for buy PXD101 the given sequence www.selleckchem.com/products/SB-203580.html type (ex. Log2 4 = 2 bits for DNA/RNA and log2 20 = 4.3 bits for proteins)] for that specific position and the height of each individual character represents the frequency of each nucleotide. ArcA as a repressor Transcription of the genes required for aerobic metabolism, energy generation, amino acid transport,

and fatty acid transport were anaerobically repressed by ArcA (Additional file 1: Table S1). In particular, the genes required for cytochrome-o-oxidase, succinyl-CoA synthetase, glutamate/aspartate transport, trehalose-6-phosphate biosynthesis, long-chain fatty acids transport, spermidine/putrescine transport, dipeptide transport, the genes encoding the two-component tricarboxylic transport system and the site-specific DNA factor for inversion stimulation (fis) were among the

highest repressed by ArcA. Genes required for L-lactate transport and metabolism, phosphate transport, acetyl-CoA transferase, APC family/D-alanine/D-serine/glycine transport, putative cationic amino acid transporter, peptide methionine sulfoxide reductase, multiple antibiotic resistance Morin Hydrate operon, as well as many poorly characterized genes were also repressed by ArcA (Additional file 1: Table S1). Additionally, some genes related to Salmonella virulence were repressed by ArcA. For example, the expression of the mgtCB operon (member of SPI-3) that is required for Mg2+ transport/growth in low-magnesium and involved in systemic infections in mice/intramacrophage survival [37–40], genes constituting the lambdoid prophage Gifsy-1 that contributes to the virulence of S. Typhimurium [41], and genes coding for a leucine-rich repeat protein (sspH2) that is translocated by and coordinately regulated with the SPI-2 TTSS [42] were highly repressed by ArcA (Figure 3A and Additional file 1: Table S1). Figure 3 Organization of major genes for (A) SPI-3, (B) ethanolamine utilization, (C) propanediol utilization, and (D-F) flagellar biosynthesis and motility.