The role of two Pseudomonas aeruginosa anthranilate synthases in tryptophan and quorum signal production

Palmer, Gregory C.; Jorth, Peter; Whiteley, Marvin

doi:10.1099/mic.0.063065-0

Cited by 41 publications

(36 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results suggest that the transcript between pqsD, pqsE, and phnA is likely expressed only under nutritionally stressed conditions and further explained our previous results which indicated that PhnA could restore PQS to a kynurenine pathway mutant only under nutrient-limiting conditions (24). These data also nicely corroborate those of Palmer et al (30), who showed that overexpression of phnAB complements tryptophan auxotrophy and PQS production in a trpE mutant. Considering all of this, we believe that we have identified a unique natural transcript that allows for differential expression of phnAB when grown under different conditions.…”

Section: Figsupporting

confidence: 81%

“…Though this enzyme seemingly could provide anthranilate for the cellular pool, TrpEG does not naturally provide anthranilate for PQS production in a phnA mutant grown without tryptophan (24). However, overexpression of TrpEG causes PQS production in a phnAB mutant grown without tryptophan, thus indicating the importance of phnAB regulation for PQS production (30).…”

mentioning

confidence: 99%

See 1 more Smart Citation

A Conserved Suppressor Mutation in a Tryptophan Auxotroph Results in Dysregulation of Pseudomonas Quinolone Signal Synthesis

et al. 2014

View full text Add to dashboard Cite

Pseudomonas aeruginosa is a common nosocomial pathogen that relies on three cell-to-cell signals to regulate multiple virulence factors. The Pseudomonas quinolone signal (PQS; 2-heptyl-3-hydroxy-4-quinolone) is one of these signals, and it is known to be important for P. aeruginosa pathogenesis. PQS is synthesized in a multistep reaction that condenses anthranilate and a fatty acid. In P. aeruginosa, anthranilate is produced via the kynurenine pathway and two separate anthranilate synthases, TrpEG and PhnAB, the latter of which is important for PQS synthesis. Others have previously shown that a P. aeruginosa tryptophan auxotroph could grow on tryptophan-depleted medium with a frequency of 10 ؊5 to 10 ؊6 . These revertants produced more pyocyanin and had increased levels of phnA transcript. In this study, we constructed similar tryptophan auxotroph revertants and found that the reversion resulted from a synonymous G-to-A nucleotide mutation within pqsC. This change resulted in increased pyocyanin and decreased PQS, along with an increase in the level of the pqsD, pqsE, and phnAB transcripts. Reporter fusion and reverse transcriptase PCR studies indicated that a novel transcript containing pqsD, pqsE, and phnAB occurs in these revertants, and quantitative real-time PCR experiments suggested that the same transcript appears in the wild-type strain under nutrientlimiting conditions. These results imply that the PQS biosynthetic operon can produce an internal transcript that increases anthranilate production and greatly elevates the expression of the PQS signal response protein PqsE. This suggests a novel mechanism to ensure the production of both anthranilate and PQS-controlled virulence factors.

show abstract

Section: Figsupporting

confidence: 81%

mentioning

confidence: 99%

A Conserved Suppressor Mutation in a Tryptophan Auxotroph Results in Dysregulation of Pseudomonas Quinolone Signal Synthesis

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The identification of this gene was part of a massive biochemical screen of various bacterial BKACE members and proved very valuable for the identification of these CoA-dependent cleavage enzyme substrates (Bastard et al, 2014). The glycine betaine-CoA derived from BKACE activity is then converted to glycine betaine and CoA by a CoA transferase, likely the DhcAB enzyme in Pseudomonas aeruginosa (Wargo & Hogan, 2009), which appears to function as a general amino acid CoA transferase (Palmer et al, 2013). After carnitine is metabolized to glycine betaine, it can function as an osmolyte (as described above) or be utilized as a sole carbon, nitrogen, and energy source if the organism encodes the necessary enzymes, as in the case for Pseudomonas aeruginosa (Wargo et al, 2008) (Hwang & Bang, 1997), Rhizobium sp.…”

Section: Carnitine As a Nutrientmentioning

confidence: 99%

Carnitine in bacterial physiology and metabolism

2015

View full text Add to dashboard Cite

Carnitine is a quaternary amine compound found at high concentration in animal tissues, particularly muscle, and is most well studied for its contribution to fatty acid transport into mitochondria. In bacteria, carnitine is an important osmoprotectant, and can also enhance thermotolerance, cryotolerance and barotolerance. Carnitine can be transported into the cell or acquired from metabolic precursors, where it can serve directly as a compatible solute for stress protection or be metabolized through one of a few distinct pathways as a nutrient source. In this review, we summarize what is known about carnitine physiology and metabolism in bacteria. In particular, recent advances in the aerobic and anaerobic metabolic pathways as well as the use of carnitine as an electron acceptor have addressed some long-standing questions in the field. Received 5 January 2015 Accepted 17 March 2015Introduction Carnitine (c-trimethylamino-b-hydroxybutyric acid) ( Fig. 1) is a quaternary amine compound that can be produced by all domains of life, and was discovered in muscle extract in 1905 by Gulewitsch & Krimberg (1905) and Kutscher (1905). It was shown to be essential for larval development of the mealworm Tenebrio molitor and was originally designated vitamin B T based on this requirement. Later, it was discovered that carnitine can be synthesized in mammals and is now considered to be a quasi-nutrient or conditionally essential nutrient (Flanagan et al., 2010), as neonates have reduced biosynthesis and rely on placental transfer of carnitine in utero and exogenous sources after birth (Combs, 2012). Fifty years after the discovery of carnitine, it was demonstrated that assorted Gram-positive and Gram-negative bacteria could use carnitine in either aerobic or anaerobic environments for a variety of cellular functions, including as an electron acceptor, as a compatible solute to survive environmental insults or as a sole carbon, nitrogen and energy source. Bacterial carnitine metabolism was most recently reviewed in 1998 (Bieber, 1988;Bremer, 1983;Kleber, 1997;Rebouche & Seim, 1998) and the field has seen important advances. This review summarizes what we knew at the time of the previous reviews and emphasizes what we have learned since, including: (i) how anaerobic bacteria synthesize and utilize crotonobetaine and carnitine as final electron acceptors, (ii) the impact of carnitine degradation by the intestinal microbiota and the genes responsible for this anaerobic conversion, (iii) the genes involved in aerobic degradation of carnitine, and (iv) how carnitine as a compatible solute impacts survival within and outside of the host. Carnitine in the environmentRecent work makes it clear that while animals represent the most readily accessible source of carnitine, carnitine is often present and sometimes abundant in soil and natural waters. Quaternary ammonium compounds are abundant in a number of soil ecosystems, including comprising a quarter of the most abundant organic nitrogen compounds in the soil water of a subalpine gras...

show abstract

“…Anthranilate synthase (AS) [EC 4.1.3.27] catalyzes the production of anthranilate from chorismate in the l -tryptophan biosynthesis branch. ASs have been characterized in bacteria (Bae et al, 1989; Ito et al, 1969; Palmer, G.C. et al, 2013), in plants (Morino et al, 2005; Saika et al, 2012; Tozawa et al, 2001) and in Saccharomyces cerevisiae (Braus, 1991; Graf et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

TrpE feedback mutants reveal roadblocks and conduits toward increasing secondary metabolism in Aspergillus fumigatus

Wang

Choera

Wiemann

et al. 2016

Fungal Genetics and Biology

View full text Add to dashboard Cite

Small peptides formed from non-ribosomal peptide synthetases (NRPS) are bioactive molecules produced by many fungi including the genus Aspergillus. A subset of NRPS utilizes tryptophan and its precursor, the non-proteinogenic amino acid anthranilate, in synthesis of various metabolites such as A. fumigatus fumiquinazolines (Fqs) produced by the fmq gene cluster. The A. fumigatus genome contains two putative anthranilate synthases - a key enzyme in conversion of anthranilic acid to tryptophan - one beside the fmq cluster and one in a region of co-linearity with other Aspergillus spp. Only the gene found in the co-linear region, trpE, was involved in tryptophan biosynthesis. We found that site-specific mutations of the TrpE feedback domain resulted in significantly increased production of anthranilate, tryptophan, p-aminobenzoate and fumiquinazolines FqF and FqC. Supplementation with tryptophan restored metabolism to near wild type levels in the feedback mutants and suggested that synthesis of the tryptophan degradation product kynurenine could negatively impact Fq synthesis. The second putative anthranilate synthase gene next to the fmq cluster was termed icsA for its considerable identity to isochorismate synthases in bacteria. Although icsA had no impact on A. fumigatus Fq production, deletion and over-expression of icsA increased and decreased respectively aromatic amino acid levels suggesting that IcsA can draw from the cellular chorismate pool.

show abstract

The role of two Pseudomonas aeruginosa anthranilate synthases in tryptophan and quorum signal production

Cited by 41 publications

References 37 publications

A Conserved Suppressor Mutation in a Tryptophan Auxotroph Results in Dysregulation of Pseudomonas Quinolone Signal Synthesis

A Conserved Suppressor Mutation in a Tryptophan Auxotroph Results in Dysregulation of Pseudomonas Quinolone Signal Synthesis

Carnitine in bacterial physiology and metabolism

TrpE feedback mutants reveal roadblocks and conduits toward increasing secondary metabolism in Aspergillus fumigatus

Contact Info

Product

Resources

About