Biology subjects

Prezioso, S.

Publications and source records attributed to Prezioso, S..

2 recordsLinked to original sources

bioRxiv2025

The interplay between glucose and aromatic compound regulation by two IclR-type transcription factors, LigR1 and LigR2, in Pseudomonas putida KT2440

The rhizosphere is a hotspot of microbial activity where plants release a diverse array of aromatic compounds, including shikimate pathway intermediates and monolignols. Pseudomonas putida KT2440, renowned for its metabolic versatility in this niche, uses largely uncharacterized regulatory and enzymatic strategies to utilize these compounds. We investigated two IclR-type transcriptional regulators, LigR1 and LigR2, that control expression of the uncharacterized lig1 and lig2 operons. We demonstrate that ligR1 deletion caused growth defects on glucose and 4-hydroxybenzoate accompanied by cell elongation and aggregation. Structural and functional analyses reveal that LigR1 and LigR2 activate the lig1 operon but repress the lig2 operon. LigR1 binding of 4-hydroxybenzoate induced repression by triggering tetramerization and increasing DNA-binding activity. In contrast, LigR2 responded to quinate, protocatechuate and 4-hydroxybenzoate to potently induce lig2 operon expression by relieving repression. While both operons cooperate in metabolizing these compounds, we propose the lig1 operon mediates influx through its major facilitator superfamily (MFS) transporter (PP_2604), whereas the lig2 operon catalyzes breakdown via a protocatechuate intermediate and the meta-cleavage pathway, supplying oxaloacetate to the TCA cycle. Importantly, we show that P. putida repurposes shikimate pathway intermediates for energy production. These findings challenge the canonical biosynthetic view of the shikimate pathway and redefine the metabolic flexibility of soil pseudomonads. We reveal a novel mechanism enabling P. putida to thrive in the chemically complex rhizosphere and open new avenues for exploring alternate roles of the shikimate pathway, emphasizing transcriptional regulators as tools to deconvolute complex metabolic landscapes. HighlightsO_LILigR1 and LigR2 transcriptionally regulate the lig1 and lig2 operons C_LIO_LILig1 operon is required for import of glucose and shikimate-derived compounds C_LIO_LILig2 operon metabolizes shikimate pathway compounds C_LIO_LIDysregulated LigR1/LigR2 expression impacts bacterial physiology C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=189 HEIGHT=200 SRC="FIGDIR/small/670189v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@9b461aorg.highwire.dtl.DTLVardef@175c73org.highwire.dtl.DTLVardef@1b6bd90org.highwire.dtl.DTLVardef@574e55_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

LasR regulates protease IV expression at suboptimal growth temperatures in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a highly versatile bacterium capable of surviving and often thriving in stressful environmental conditions. Here we report the effect of two environmental conditions, temperature and growth phase, on the P. aeruginosa PAO1 transcriptome. As P. aeruginosa is well-known for its growth phase dependent phenotypes and gene regulation, our goal was to determine how temperature altered global gene expression at exponential versus stationary phase and to characterize how growth phase affects thermoregulation. To do this, we grew PAO1 in parallel at 25{degrees}C and 37{degrees}C and sampled the same populations first at exponential phase and then again at stationary phase and assessed gene expression by RNA-sequencing. We found that temperature regulated hundreds of genes at, and unique to, exponential and stationary phase. We also grew PAO1 and an isogenic {Delta}lasR mutant at 25{degrees}C and 37{degrees}C and sampled populations at stationary phase to define LasR-regulated genes at each temperature by RNA-sequencing. LasR regulated most of its target genes similarly at 25{degrees}C and 37{degrees}C, although we identified a subset of genes whose regulation by LasR was affected by temperature. This work provides a comprehensive thermoregulon for PAO1 at two distinct growth phases, as well as growth phase transcriptomics at two temperatures, and expands our understanding of quorum sensing regulation under different environmental conditions that P. aeruginosa encounters. IMPORTANCEPseudomonas aeruginosa is a highly adaptable opportunistic pathogen with a repertoire of mechanisms for surviving in diverse and often challenging environments yet is most often studied at 37{degrees}C as the optimum temperature for growth. To better understand how this bacterium survives in the environment versus the human body, we performed transcriptomics on P. aeruginosa grown at 25{degrees}C and 37{degrees}C. At each temperature, we examined both exponential and stationary phases. We also determined the LasRI quorum sensing regulon at 37{degrees}C compared to 25{degrees}C using a {Delta}lasR mutant, which uncovered a suite of previously unrecognized LasR-regulated genes. Our work provides a comprehensive transcriptomic resource for thermoregulation of P. aeruginosa at two growth phases, as well as growth phase and LasR regulation at two temperatures.

microbiology↗