Transcriptome Analysis of the ArgR Regulon inPseudomonas aeruginosa

Abstract

Arginine metabolism in pseudomonads with multiple catabolic pathways for its utilization as carbon and nitrogen sources is of particular interest as the model system to study control of metabolic integration. We performed transcriptome analyses to identify genes controlled by the arginine regulatory protein ArgR and to better understand arginine metabolic pathways of P. aeruginosa. We compared gene expression in wild-type strain PAO1 with that in argR mutant strain PAO501 grown in glutamate minimal medium in the presence and absence of arginine. Ten putative transcriptional units of 28 genes were inducible by ArgR and arginine, including all known ArgR-regulated operons under aerobic conditions. The newly identified genes include the putative adcAB operon, which encodes a catabolic arginine decarboxylase and an antiporter protein, and PA0328, which encodes a hypothetical fusion protein of a peptidase and a type IV autotransporter. Also identified as members of the arginine network are the following solute transport systems: PA1971 (braZ) for branched-chain amino acids permease; PA2042 for a putative sodium:serine symporter; PA3934, which belongs to the family of small oligopeptide transporters; and PA5152-5155, which encodes components of an ABC transporter for a putative opine uptake system. The effect of arginine on the expression of these genes was confirmed by lacZ fusion studies and by DNA binding studies with purified ArgR. Only five transcriptional units of nine genes were qualified as repressible by ArgR and arginine, with three operons (argF, carAB, and argG) in arginine biosynthesis and two operons (gltBD and gdhA) in glutamate biosynthesis. These results indicate that ArgR is important in control of arginine and glutamate metabolism and that arginine and ArgR may have a redundant effect in inducing the uptake systems of certain compounds.Pseudomonas aeruginosa possesses four different catabolic pathways for utilization of arginine (11): the arginine deiminase (ADI) pathway, the arginine succinyltransferase (AST) pathway, the arginine decarboxylase (ADC) pathway, and the arginine dehydrogenase (ADH) pathway (Fig. 1). Under aerobic conditions, Haas and coworkers have established that arginine utilization occurs mainly through the AST pathway, which converts arginine to glutamate (20,43). Recent studies in the laboratories of Lu and Abdelal have shown that the aru operon, which encodes the AST pathway, and the gdhB gene, which encodes a catabolic glutamate dehydrogenase, are inducible by arginine and that this effect is mediated by ArgR (18,24). In P. aeruginosa, ArgR, the arginine-responsive regulator protein, is autoinduced from the aot-argR operon for arginine uptake and regulation (35). The ArgR protein of P. aeruginosa belongs to the AraC/XylS family of transcriptional regulators (7) and is thus quite different in structure and function from the ArgR proteins of enteric bacteria and Bacillus subtilis (3,4,6,23,25), which have a high degree of similarity in their three-dimensional structures and DNA...

σSControls Multiple Pathways Associated with Intracellular Multiplication ofLegionella pneumophila

“…Subsequent steps of arginine biosynthesis can be accomplished (100), and the genes required for the conversion of ornithine to arginine, argFGH, are divergent from argR (lpg0490) in a region that also includes a putative ABC transporter (lpg0491-lpg0496). In E. coli and P. aeruginosa, ArgR regulates the expression of a number of transporters required for the uptake of amino acids and other compounds (13,60), and ArgR has been predicted to regulate arginine uptake from the host cell in some members of the Chlamydiaceae (88). It is intriguing to speculate that ArgR regulates one or more L. pneumophila transporters required for the acquisition of critical nutrients from the host cell.…”

Molecular characterization of lysR-lysXE, gcdR-gcdHG and amaR-amaAB operons for lysine export and catabolism: a comprehensive lysine catabolic network in Pseudomonas aeruginosa PAO1

“…10, there are at least four transcriptional regulators that respond to Arg and Lys -LysR (L-Lys), AruSR (L-Lys and L-Arg), ArgR (L-Arg) and DauR (D-Lys and D-Arg). P. aeruginosa is well equipped to grow more efficiently on Arg than on Lys, with the ArgR regulator in response to L-Arg as the major player to control the entire arginine network (Li et al, 2010;Lu et al, 2004), including the AotJQMP transporter for L-Arg and L-Lys uptake. Furthermore, ArgR extends its influence to Lys catabolism through its control of ldcA for L-Lys decarboxylase (Chou et al, 2010), dauBAR-dauT for D-Lys/D-Arg dehydrogenase and uptake, and potentially of lysP and aruH for L-Lys uptake and L-Lys L-Arg aminotransferase (Yang & Lu, 2007b).…”

Arginine racemization by coupled catabolic and anabolic dehydrogenases

“…As shown in Table 1, the dauBART genes were significantly induced by D-arginine. Surprisingly, D-arginine exerts the same effects as L-arginine (15) on all genes in the ArgR regulon (as represented by genes in group II for the activation effect and genes in group IV for the repression effect of Table 1).…”