RESUMO
Pseudomonas aeruginosa is a ubiquitous microorganism, capable of colonizing a wide range of habitats due to its metabolic versatility and wide adaptability to different conditions. Industrial and environmental research involving petroleum microbiology play a pivotal role in controlling many technical, operational, and environmental issues. P. aeruginosa PA1-Petro strain was isolated from oil production water in Northeastern Brazil. Herein we report the genomic sequencing and annotation of PA1-Petro, and a comparative genomics study against two widely used reference P. aeruginosa strains (PAO1 and PA14). PA1-Petro has a genome of 6,893,650 bp, the largest among the three analyzed in this study, with a 65.87% GC content. The analyzes resulted in a wide repertoire of 544 unique genes in PA1-Petro, and the highest copy numbers of common genes among the three strains (PA1-Petro, PAO1 and PA14). Unique sequences are hypothetical proteins, prophage sequences, mobile genetic elements, transcriptional regulators, metal resistance genes to copper, tellurium and arsenic, type IE CRISPR-Cas, Type VI Secretion System (T6SS)-associated proteins, and a toxin-antitoxin system. Taken together, these results provide intriguing insights on adaptive evolution within PA1-Petro genome, adding unprecedented information to the species' plasticity and ubiquitous characteristics.
RESUMO
In this study, we examine the impact of transcriptional network rearrangements driven by horizontal gene acquisition in PhoP and SlyA regulons using as a case study a phytopathosystem comprised of potato tubers and the soft-rot pathogen Pectobacterium brasiliense 1692 (Pb1692). Genome simulations and statistical analyses uncovered the tendency of PhoP and SlyA networks to mobilize lineage-specific traits predicted as horizontal gene transfer at late infection, highlighting the prominence of regulatory network rearrangements in this stage of infection. The evidence further supports the circumscription of two horizontally acquired quorum-sensing regulators (carR and expR1) by the PhoP network. By recruiting carR and expR1, the PhoP network also impacts certain host adaptation- and bacterial competition-related systems, seemingly in a quorum sensing-dependent manner, such as the type VI secretion system, carbapenem biosynthesis, and plant cell wall-degrading enzymes (PCWDE) like cellulases and pectate lyases. Conversely, polygalacturonases and the type III secretion system (T3SS) exhibit a transcriptional pattern that suggests quorum-sensing-independent regulation by the PhoP network. This includes an uncharacterized novel phage-related gene family within the T3SS gene cluster that has been recently acquired by two Pectobacterium species. The evidence further suggests a PhoP-dependent regulation of carbapenem- and PCWDE-encoding genes based on the synthesized products' optimum pH. The PhoP network also controls slyA expression in planta, which seems to impact carbohydrate metabolism regulation, especially at early infection, when 76.2% of the SlyA-regulated genes from that category also require PhoP to achieve normal expression levels.IMPORTANCE Exchanging genetic material through horizontal transfer is a critical mechanism that drives bacteria to efficiently adapt to host defenses. In this report, we demonstrate that a specific plant-pathogenic species (from the Pectobacterium genus) successfully integrated a population density-based behavior system (quorum sensing) acquired through horizontal transfer into a resident stress-response gene regulatory network controlled by the PhoP protein. Evidence found here underscores that subsets of bacterial weaponry critical for colonization, typically known to respond to quorum sensing, are also controlled by PhoP. Some of these traits include different types of enzymes that can efficiently break down plant cell walls depending on the environmental acidity level. Thus, we hypothesize that PhoP's ability to elicit regulatory responses based on acidity and nutrient availability fluctuations has strongly impacted the fixation of its regulatory connection with quorum sensing. In addition, another global gene regulator, known as SlyA, was found under the PhoP regulatory network. The SlyA regulator controls a series of carbohydrate metabolism-related traits, which also seem to be regulated by PhoP. By centralizing quorum sensing and slyA under PhoP scrutiny, Pectobacterium cells added an advantageous layer of control over those two networks that potentially enhances colonization efficiency.