TrgI, toluene repressed gene I, a novel gene involved in toluene-tolerance in Pseudomonas putida S12

Abstract

Pseudomonas putida S12 is well known for its remarkable solvent tolerance. Transcriptomics analysis of this bacterium grown in toluene-containing chemostats revealed the differential expression of 253 genes. As expected, the genes encoding one of the major solvent tolerance mechanisms, the solvent efflux pump SrpABC and its regulatory genes srpRS were heavily up-regulated. The increased energy demand brought about by toluene stress was also reflected in transcriptional changes: genes involved in sugar storage were down-regulated whereas genes involved in energy generation such as isocitrate dehydrogenase and NADH dehydrogenases, were up-regulated in the presence of toluene. Several flagella-related genes were upregulated and a large group of transport genes were downregulated. In addition, a novel Pseudomonas-specific gene was identified to be involved in toluene tolerance of P. putida S12. This toluene-repressed gene, trgI, was heavily downregulated immediately upon toluene exposure in batch cultures. The relationship of trgI with solvent tolerance was confirmed by the increased resistance to toluene shock and toluene induced lysis of trgI knock-out mutants. We propose that down-regulation of trgI plays a role in the first line of defence against solvents.

Engineering of Pseudomonas taiwanensis VLB120 for Constitutive Solvent Tolerance and Increased Specific Styrene Epoxidation Activity

“…Besides the efflux pumps TtgABC and TtgGHI, which typically act as a long-term response to solvent exposure, additional genes were found, which have been proposed to be involved in first-line defense mechanisms against solvent toxicity. A cis/trans isomerase, responsible for the cis-to trans-isomerization of unsaturated fatty acids and the related increase in membrane rigidity (60), the toluene repressed gene trgI, proposed to be involved in altering the outer cell structure (61), and the AGZ33638.1 gene, encoding the multidrug efflux membrane protein PP1272 (62). These findings on the genomic level confirm the previously described tolerance of P. taiwanensis VLB120 toward styrene (42,63).…”

Redundancy in putrescine catabolism in solvent tolerant Pseudomonas putida S12

“…This study revealed a number of genes presumably involved in putrescine transport and metabolism that were differentially expressed in this strain compared to a non-producing control strain (Verhoef et al, 2010). Also in other studies, polyamine-associated genes were found to be differentially expressed in solvent-exposed P. putida strains (Duque et al, 2007;Volkers et al, 2009).…”

“…The cDNA samples were analysed on high-density, custom-made P. putida KT2440-genome based microarrays (Affymetrix) with additional probe sets of known sequences of P. putida S12 and related strains Wierckx et al, 2008). The arrays were hybridized and scanned according to modified manufacturer's protocols Volkers et al, 2009;Wierckx et al, 2008). GeneSpring GX Software (version 7.3.1) and the GC RMA algorithm was used for data analysis (Volkers et al, 2009).…”

“…Pseudomonas putida S12 displays exceptional tolerance towards a range of toxic organic solvents at concentrations which are usually lethal to other microorganisms (Isken and de Bont, 1998;Ramos et al, 2002;Volkers et al, 2009). Solvent-tolerant P. putida strains dispose of special mechanisms to cope with hydrophobic toxic compounds, which include modifications to the inner and outer membrane, as well as active extrusion of solvents through membrane-associated efflux pumps (Kieboom et al, 1998;Ramos et al, 1998).…”

Extremophiles and their Application to Biofuel Research

“…Shuffling yielded 15 novel enzymes with better catalytic performance and thermostability than those of parents (Heinzelman et al, 2009a,b). In addition, thermostability has been studied by comparing the structures of endoglucanases and lipases from several different sources (Danson and Hough, 1998;Ladenstein and Antranikian, 1998;Crennell et al, 2002;Sinchaikul et al, 2002;Tyndall et al, 2002;Volkers et al, 2009). General trends and potential strategies for increasing internal stabilization have been reviewed and include an increase in ionpair networks, disulfide and salt bridging, hydrogen bonding, hydrophobic and aromatic interactions, and stabilization of surface-exposed amino acids (Ladenstein and Antranikian, 1998;Li et al, 2005).…”