Global dynamics of Escherichia coli phosphoproteome in central carbon metabolism under changing culture conditions

Little is known about the role of global phosphorylation events in the control of prokaryote metabolism. By performing a detailed analysis of all protein phosphorylation events previously reported in Escherichia coli, dynamic changes in protein phosphorylation were elucidated under three different culture conditions. Using scheduled reaction monitoring, the phosphorylation ratios of 82 peptides corresponding to 71 proteins were quantified to establish whether serine (S), threonine (T) and tyrosine (Y) phosphorylation events displayed a dynamic profile under changing culture conditions. The ratio of phosphorylation for 23 enzymes from central carbon metabolism was found to be dynamic. The data presented contributes to our understanding of the global role of phosphorylation in bacterial metabolism and highlight that phosphorylation is an important, yet poorly understood, regulatory mechanism of metabolism control in bacteria

Successful pedicled vertical rectus abdominis myocutaneous flap reconstruction with negative-pressure wound therapy for deep sternal wound infection: a case report and comprehensive review

IntroductionDeep sternal wound infection (DSWI) is a serious complication that may occur after median sternotomy, with potentially devastating consequences. By reporting our case and analyzing the existing literature, this article aimed to provide a thorough understanding of the role of negative-pressure wound therapy (NPWT) and the importance of flap choice in managing DSWI accompanied by severe heart injury and high hemodynamic risk.Case descriptionA 60-year-old woman with severe aortic stenosis, aortic valve regurgitation, and heart failure underwent redo sternotomy, which resulted in an intraoperative right ventricle injury. She required extracorporeal membrane oxygenation support because of low blood pressure and subsequently developed complications, including surgical site hematoma, wound dehiscence, and fat necrosis. She was referred for wound closure, where a significant 10 × 20-cm soft tissue defect in the anterior chest wall was observed. A pedicled vertical rectus abdominis myocutaneous flap addressed the soft tissue defect. The wound showed remarkable improvement at the 8-month follow-up visit.ConclusionsDSWI management is a complex and multifaceted challenge. NPWT, when combined with appropriate surgical strategies, including wound debridement and flap selection, may promote successful wound healing. This case report highlights the successful management of a complex DSWI using a multidisciplinary approach, including debridement, appropriate antibiotic therapy, and free-flap reconstruction, which resulted in favorable outcomes

Evaluation of heavy metal tolerance level of the Antarctic bacterial community in biodegradation of waste canola oil

Heavy metal contamination is accidentally becoming prevalent in Antarctica, one of the world’s most pristine regions. Anthropogenic as well as natural causes can result in heavy metal contamination. Each heavy metal has a different toxic effect on various microorganisms and species, which can interfere with other pollutant bioremediation processes. This study focused on the effect of co-contaminant heavy metals on waste canola oil (WCO) biodegradation by the BS14 bacterial community collected from Antarctic soil. The toxicity of different heavy metals in 1 ppm of concentration to the WCO-degrading bacteria was evaluated and further analyzed using half maximal inhibition concentration (IC50) and effective concentration (EC50) tests. The results obtained indicated that Ag and Hg significantly impeded bacterial growth and degradation of WCO, while interestingly, Cr, As, and Pb had the opposite effect. Meanwhile, Cd, Al, Zn, Ni, Co, and Cu only slightly inhibited the bacterial community in WCO biodegradation. The IC50 values of Ag and Hg for WCO degradation were found to be 0.47 and 0.54 ppm, respectively. Meanwhile, Cr, As, and Pb were well-tolerated and induced bacterial growth and WCO degradation, resulting in the EC50 values of 3.00, 23.80, and 28.98 ppm, respectively. The ability of the BS14 community to tolerate heavy metals while biodegrading WCO in low-temperature conditions was successfully confirmed, which is a crucial aspect in biodegrading oil due to the co-contamination of oil and heavy metals that can occur simultaneously, and at the same time it can be applied in heavy metal-contaminated areas

Temporal dynamics of the Saccharopolyspora erythraea phosphoproteome

Actinomycetes undergo a dramatic reorganization of metabolic and cellular machinery during a brief period of growth arrest (metabolic switch) preceding mycelia differentiation and the onset of secondary metabolite biosynthesis. This study explores the role of phosphorylation in coordinating the metabolic switch in the industrial actinomycete Saccharopolyspora erythraea. A total of 109 phosphopeptides from 88 proteins were detected across a 150-h fermentation using open-profile two-dimensional LC-MS proteomics and TiO2 enrichment. Quantitative analysis of the phosphopeptides and their unphosphorylated cognates was possible for 20 pairs that also displayed constant total protein expression. Enzymes from central carbon metabolism such as putative acetyl-coenzyme A carboxylase, isocitrate lyase, and 2-oxoglutarate dehydrogenase changed dramatically in the degree of phosphorylation during the stationary phase, suggesting metabolic rearrangement for the reutilization of substrates and the production of polyketide precursors. In addition, an enzyme involved in cellular response to environmental stress, trypsin-like serine protease (SACE_6340/NC_009142_6216), decreased in phosphorylation during the growth arrest stage. More important, enzymes related to the regulation of protein synthesis underwent rapid phosphorylation changes during this stage. Whereas the degree of phosphorylation of ribonuclease Rne/Rng (SACE_1406/NC_009142_1388) increased during the metabolic switch, that of two ribosomal proteins, S6 (SACE_7351/NC_009142_7233) and S32 (SACE_6101/NC_009142_5981), dramatically decreased during this stage of the fermentation, supporting the hypothesis that ribosome subpopulations differentially regulate translation before and after the metabolic switch. Overall, we show the great potential of phosphoproteomic studies to explain microbial physiology and specifically provide evidence of dynamic protein phosphorylation events across the developmental cycle of actinomycetes

Antarctic heavy metal pollution and remediation efforts: state of the art of research and scientific publications

In Antarctica, human activities have been reported to be the major cause of the accumulation of heavy metal contaminants. A comprehensive bibliometric analysis of publications on heavy metal contamination in Antarctica from year 2000 to 2020 was performed to obtain an overview of the current landscape in this line of research. A total of 106 documents were obtained from Scopus, the largest citation database. Extracted data were analysed, and VOSviewer software was used to visualise trends. The result showed an increase in publications and citations in the past 20 years indicating the rising interest on heavy metal contamination in the Antarctic region. Based on the analysis of keywords, the publications largely discuss various types of heavy metals found in the Antarctic water and sediment. The analysis on subject areas detects multiple disciplines involved, wherein the environmental science was well-represented. The top countries and authors producing the most publication in this feld were from Australia, China, Brazil and Chile. Numerous eforts have been exercised to investigate heavy metal pollution and its mitigation approaches in the region in the past decades. This paper not only is relevant for scholars to understand the development status and trends in this feld but also ofers clear insights on the future direction of Antarctic heavy metal contamination and remediation research

Alternative regulation of HIF-1α stability through Phosphorylation on Ser451

The hypoxia-inducible factor (HIF-1 alpha) functions as a master regulator of oxygen homeostasis. Oxygen dependent hydroxylation of HIF-1 alpha is tightly regulated by prolyl hydroxylase domain containing proteins (PHD1, PHD2, and PHD3). The prolyl hydroxylation facilitates the recruitment of the von HippelLindau (VHL) protein, leading to ubiquitination and degradation of HIF-1 alpha by the proteasomes. Besides prolyl hydroxylation, phosphorylation of HIF-1 alpha is another central post-translational modification, which regulates its stability under hypoxic conditions as well as normoxic conditions. By use of LC/MS/MSbased analysis, we were able to identify a specific serine residue (Ser451) of HIF-1 alpha phosphorylated under hypoxic conditions. Using plasmids expressing wild type (WT), non-phosphorylatable mutant HIF1 alpha (S451A), and phosphomimetic mutant HIF-1 alpha (S451E), we demonstrated that the phosphorylation at Ser451 is important in maintaining the HIF-1 alpha protein stability. Notably, phosphorylation at S451 interrupts the interaction of HIF-1 alpha with PHD and pVHL. A phosphomimetic construct of HIF-1 alpha at Ser451 (S451E) is significantly more stable than WT HIF-1 alpha under normoxic conditions. Cells transfected with unphosphorylatable HIF-1 alpha exhibited significantly lower HIF-1 transcriptional activity than WT cells and markedly reduced tumor cell migration. Further, tumors derived from the phosphomimetic mutant cells grew faster, whereas the tumors derived from non-phosphorylatable mutant cells grew slower than the control tumors, suggesting that the phosphorylation of HIF-1 alpha at the Ser451 site is critical to promote tumor growth in vivo. Taken together, our data suggest an alternative mechanism responsible for the regulation of HIF-1 alpha stability. (C) 2021 Elsevier Inc. All rights reserved.

Mathematical modelling of canola oil biodegradation and optimisation of biosurfactant production by an antarctic bacterial consortium using response surface methodology

An Antarctic soil bacterial consortium (reference BS14) was confirmed to biodegrade canola oil, and kinetic studies on this biodegradation were carried out. The purpose of this study was to examine the ability of BS14 to produce biosurfactants during the biodegradation of canola oil. Secondary mathematical equations were chosen for kinetic analyses (Monod, Haldane, Teissier–Edwards, Aiba and Yano models). At the same time, biosurfactant production was confirmed through a preliminary screening test and further optimised using response surface methodology (RSM). Mathematical modelling demonstrated that the best-fitting model was the Haldane model for both waste (WCO) and pure canola oil (PCO) degradation. Kinetic parameters including the maximum degradation rate (μmax) and maximum concentration of substrate tolerated (Sm) were obtained. For WCO degradation these were 0.365 min−1 and 0.308%, respectively, while for PCO they were 0.307 min−1 and 0.591%, respectively. The results of all preliminary screenings for biosurfactants were positive. BS14 was able to produce biosurfactant concentrations of up to 13.44 and 14.06 mg/mL in the presence of WCO and PCO, respectively, after optimisation. The optimum values for each factor were determined using a three-dimensional contour plot generated in a central composite design, where a combination of 0.06% salinity, pH 7.30 and 1.55% initial substrate concentration led to the highest biosurfactant production when using WCO. Using PCO, the highest biosurfactant yield was obtained at 0.13% salinity, pH 7.30 and 1.25% initial substrate concentration. This study could help inform the development of large-scale bioremediation applications, not only for the degradation of canola oil but also of other hydrocarbons in the Antarctic by utilising the biosurfactants produced by BS14