Mechanistic and Structural Studies of Salicylate Biosynthesis in Pseudomonas aeruginosa
type: CreativeWork
description: Iron is an essential element for most pathogenic bacteria. To survive and establish infections in host tissues, these pathogens must compete with the host organism for iron. One strategy is to excrete iron-chelator siderophores with very high affinity to ferric iron in the low iron environment of the host. The phenolate type siderophore, such as pyochelin in Pseudomonas aeruginosa, uses salicylate derived from chorismate as a precursor. Studies have shown that the salicylate activation by adenylation for incorporation to siderophores is associated with the growth and virulence of some pathogens. The inhibition of salicylate biosynthesis, and hence, siderophore production is considered an attractive target for the development of novel antimicrobial agents. In P. aeruginosa, salicylate is derived from chorismate via isochorismate by two enzymes: isochorismate synthase (PchA) and isochorismate-pyruvate lyase (IPL, PchB). PchB eliminates the enolpyruvyl side chain from isochorismate through a biologically unusual pericyclic reaction mechanism. PchB can also perform an adventitious pericyclic reaction that rearranges chorismate to prephenate possibly due to the homology to the E. coli chorismate mutase (CM). The primary contribution to lower the activation energy for enzymatic pericyclic reactions is controversial and may be arise from electrostatic stabilization of the transition state, or conformational stabilization of the reactive substrate. Structural and mutational studies on a key residue, lysine 42, of the active site loop suggest that rate enhancement of the two pericyclic reactions (IPL and CM) performed by PchB results from both the transition state stabilization and the reactive substrate conformation, but the relative contributions are different for each reaction. A mutation with less active site loop mobility, A43P indicates that the loop dynamics is related to catalysis. The I87T structure reveals a larger disordered region compared to the wild type struct…
abstract: Iron is an essential element for most pathogenic bacteria. To survive and establish infections in host tissues, these pathogens must compete with the host organism for iron. One strategy is to excrete iron-chelator siderophores with very high affinity to ferric iron in the low iron environment of the host. The phenolate type siderophore, such as pyochelin in Pseudomonas aeruginosa, uses salicylate derived from chorismate as a precursor. Studies have shown that the salicylate activation by adenylation for incorporation to siderophores is associated with the growth and virulence of some pathogens. The inhibition of salicylate biosynthesis, and hence, siderophore production is considered an attractive target for the development of novel antimicrobial agents. In P. aeruginosa, salicylate is derived from chorismate via isochorismate by two enzymes: isochorismate synthase (PchA) and isochorismate-pyruvate lyase (IPL, PchB). PchB eliminates the enolpyruvyl side chain from isochorismate through a biologically unusual pericyclic reaction mechanism. PchB can also perform an adventitious pericyclic reaction that rearranges chorismate to prephenate possibly due to the homology to the E. coli chorismate mutase (CM). The primary contribution to lower the activation energy for enzymatic pericyclic reactions is controversial and may be arise from electrostatic stabilization of the transition state, or conformational stabilization of the reactive substrate. Structural and mutational studies on a key residue, lysine 42, of the active site loop suggest that rate enhancement of the two pericyclic reactions (IPL and CM) performed by PchB results from both the transition state stabilization and the reactive substrate conformation, but the relative contributions are different for each reaction. A mutation with less active site loop mobility, A43P indicates that the loop dynamics is related to catalysis. The I87T structure reveals a larger disordered region compared to the wild type struct…
author: Luo, Qianyi
language: EN
keywords: Chemistry, Biochemistry, Chorismate mutase pchb, Isochorismate synthase pcha, Isochorismate-pyruvate lyase pchb, Salicylate biosynthesis
date published: 2009-04-29
date modified: 2026-07-24T02:45:19Z
provider: University of Kansas
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Kansas

PropertyValue
property ID: Handle
value: http://hdl.handle.net/1808/6305