Pyoluteorin regulates the biosynthesis of 2,4-DAPG through the TetR family transcription factor PhlH in Pseudomonas protegens Pf-5.

Soil and rhizosphere bacteria act as a rich source of secondary metabolites, effectively fighting against a diverse array of pathogens. Certain Pseudomonas species harbor biosynthetic gene clusters for producing both pyoluteorin and 2,4-diacetylphloroglucinol (2,4-DAPG), which are polyketides that exhibit highly similar antimicrobial spectrum against bacteria and fungi or oomycete. A complex cross talk exists between pyoluteorin and 2,4-DAPG biosynthesis, and production of 2,4-DAPG was strongly repressed by pyoluteorin, yet the underlying mechanism is still elusive. In this study, we find that the TetR family transcription factor PhlH is involved in the cross talk between pyoluteorin and 2,4-DAPG biosynthesis. PhlH binds to a palindromic sequence within the promoter of phlG (PphlG), which encodes a C-C bond hydrolase responsible for degrading 2,4-DAPG. As a signaling molecule, pyoluteorin disrupts the PhlH-PphlG complex by binding to PhlH, leading to decreased levels of 2,4-DAPG. Proteomics data suggest that pyoluteorin regulates multiple physiological processes including fatty acid biosynthesis and transportation of taurine, siderophore, and amino acids. Our work not only reveals a novel mechanism of cross talk between pyoluteorin and 2,4-DAPG biosynthesis, but also highlights pyoluteorin's role as a messenger in the complex communication network of Pseudomonas.IMPORTANCEAntibiosis serves as a crucial defense mechanism for microbes against invasive bacteria and resource competition. These bacteria typically orchestrate the production of multiple antibiotics in a coordinated fashion, wherein the synthesis of one antibiotic inhibits the generation of another. This strategic coordination allows the bacterium to focus its resources on producing the most advantageous antibiotic under specific circumstances. However, the underlying mechanisms of distinct antibiotic production in bacterial cells remain largely elusive. In this study, we reveal that the TetR family transcription factor PhlH detects the secondary metabolite pyoluteorin and mediates the cross talk between pyoluteorin and 2,4-DAPG biosynthesis in the biocontrol strain Pseudomonas protegens Pf-5. These findings hold promise for future research, potentially informing the manipulation of these systems to enhance the effectiveness of biocontrol agents.

The Regulator PltZ Regulates a Putative ABC Transporter System PltIJKNOP of Pseudomonas aeruginosa ATCC 27853 in Response to the Antimicrobial 2,4-Diacetylphloroglucinol.

Pseudomonas aeruginosa is an opportunistic pathogen commonly infecting immunocompromised patients with diseases like cystic fibrosis (CF) and cancers and has high rates of recurrence and mortality. The treatment efficacy can be significantly worsened by the multidrug resistance (MDR) of P. aeruginosa, and there is increasing evidence showing that it is easy for this pathogen to develop MDR. Here, we identified a gene cluster, pltZ-pltIJKNOP, which was originally assumed to be involved in the biosynthesis of an antimicrobial pyoluteorin, significantly contributing to the antibiotic resistance of P. aeruginosa ATCC 27853. Moreover, the TetR family regulator PltZ binds to a semi-palindromic sequence in the promoter region of the pltIJKNOP operon and recognizes the antimicrobial 2,4-diacetylphloroglucinol (2,4-DAPG), which in turn induces the expression of the pltIJKNOP operon. Using quantitative proteomics method, it was indicated that the regulator PltZ also plays an important role in maintaining metabolic hemostasis by regulating the transporting systems of amino acids, glucose, metal ions, and bacteriocins.

Increased microparticle levels in middle-aged and elderly patients with insomnia may be involved in the pathogenesis of arteriosclerosis.

BACKGROUND: Insomnia may affect vascular factors and promote arteriosclerosis. Microparticles (MPs) are a heterogeneous group of bioactive small vesicles that can be found in blood and body fluids following activation, necrosis or apoptosis of virtually any eukaryotic cells. MPs are believed to participate in the pathogenesis of atherosclerosis. Few studies have been concerned with the microparticle level in patients with sleep disorder. The purpose of the present study is to measure the levels of endothelial microparticles (EMPs), platelet microparticles (PMPs) and leukocyte-derived microparticles (LMPs) in middle-aged and elderly patients with or without insomnia. METHODS: Patients with insomnia (N.=30) and without insomnia (N.=18) were enrolled. The insomnia group covered patients with chronic insomnia (N.=16) and acute insomnia (N.=14). Levels of EMPs (CD31 +, CD62E +) and PMPs (CD41a +, CD42a +) and granulocyte-derived (CD11a +) MPs were measured. Flow cytometry was performed on the Beckman Coulter analyzer. Reference gate was defined for the level of MPs using 0.22-0.45-0.88µm microspheres, and the size gate for MPs was 0.5-1.0µm. RESULTS: Of all types of MPs detected, the levels of CD31 +MPs, CD62E +MPs and CD11a +MPs were significantly higher in the insomnia group than in the non-insomnia group (P<0.05). Besides, compared with acute insomnia, the levels of CD31 + MPs and CD11a +MPs were significantly higher in chronic insomnia (P<0.001). CONCLUSIONS: In insomnia patients, atherosclerosis progression may be increased by the CD31+ EMPs-mediated apoptosis and endothelial injury. The level of CD11a+ LMPs kept increasing as insomnia persisted, which may indicate atherosclerosis progression.

[Application of throat swab nested PCR in the diagnosis of congenital human cytomegalovirus infection in neonates].

OBJECTIVE: To evaluate the clinical application value of throat swab nested PCR for detecting active congenital human cytomegalovirus (HCMV) infection in neonates. METHODS: The throat swabs and umbilical cord blood specimens from 51 neonates were collected for nested PCR assay for HCMV glycoprotein B (gB) gene. Moreover, 18 of them were subjected to a pp65 antigen test. RESULTS: The sensitivity and specificity of throat swab nested PCR for HCMV gB gene were 67% and 75%, respectively, and the positive and negative predictive values were 57% and 82%, respectively. CONCLUSIONS: Throat swab nested PCR assay for HCMV gB gene is non-invasive, rapid, and highly sensitive for HCMV detection and holds promise as an excellent screening technology for detecting active congenital HCMV infection in neonates.