L-Lysine Catabolism Is Controlled by L-Arginine and ArgR in Pseudomonas aeruginosa PAO1

CMUR > College of Medicine > Department of Medical Laboratory Science and Biotechnology > Journal articles > Item 310903500/34982

Please use this identifier to cite or link to this item: http://ir.cmu.edu.tw/ir/handle/310903500/34982

Title:	L-Lysine Catabolism Is Controlled by L-Arginine and ArgR in Pseudomonas aeruginosa PAO1
Authors:	(Han Ting Chou);(Mohamed Hegazy);盧仲達(Chung-Dar Lu)*
Contributors:	醫學檢驗生物技術學系
Keywords:	L-Lysine Catabolism;Pseudomonas
Date:	2010-11
Issue Date:	2010-11-24 16:10:55 (UTC+8)
Abstract:	In comparison to other pseudomonads, Pseudomonas aeruginosa grows poorly in L-lysine as a sole source of nutrient. In this study, the ldcA gene (lysine decarboxylase A; PA1818), previously identified as a member of the ArgR regulon of L-arginine metabolism, was found essential for L-lysine catabolism in this organism. LdcA was purified to homogeneity from a recombinant strain of Escherichia coli, and the results of enzyme characterization revealed that this pyridoxal-5-phosphate-dependent decarboxylase takes L-lysine, but not L-arginine, as a substrate. At an optimal pH of 8.5, cooperative substrate activation by L-lysine was depicted from kinetics studies, with calculated Km and Vmax values of 0.73 mM and 2.2 mole/mg/min, respectively. Contrarily, the ldcA promoter was induced by exogenous L-arginine but not by L-lysine in the wild-type strain PAO1, and the binding of ArgR to this promoter region was demonstrated by electromobility shift assays. This peculiar arginine control on lysine utilization was also noted from uptake experiments in which incorporation of radioactively labeled L-lysine was enhanced in cells grown in the presence of L-arginine but not L-lysine. Rapid growth on L-lysine was detected in a mutant devoid of the main arginine catabolic pathway and with a higher basal level of the intracellular L-arginine pool and hence elevated ArgR-responsive regulons, including ldcA. Growth on L-lysine as a nitrogen source can also be enhanced when the aruH gene encoding an arginine/lysine:pyruvate transaminase was expressed constitutively from plasmids; however, no growth of the ldcA mutant on L-lysine suggests a minor role of this transaminase in L-lysine catabolism. In summary, this study reveals a tight connection of lysine catabolism to the arginine regulatory network, and the lack of lysine-responsive control on lysine uptake and decarboxylation provides an explanation of L-lysine as a poor nutrient for P. aeruginosa.
Relation:	JOURNAL OF BACTERIOLOGY 192(22):5874-5880
Appears in Collections:	[Department of Medical Laboratory Science and Biotechnology ] Journal articles

Files in This Item:

File	Description	Size	Format
20101113225540.pdf		757Kb	Adobe PDF	425	View/Open

Loading...