A Novel Reperfusion Strategy for Primary Percutaneous Coronary Intervention in Patients with Acute ST-Segment Elevation Myocardial Infarction: A Prospective Case Series.

BACKGROUND: Ischemia reperfusion injury (IRI) remains a major problem in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). We have developed a novel reperfusion strategy for PCI and named it "volume-controlled reperfusion (VCR)". The aim of the current study was to assess the safety and feasibility of VCR in patients with STEMI. METHODS: Consecutive patients admitted to Beijing Chaoyang Hospital with STEMI were prospectively enrolled. The feasibility endpoint was procedural success. The safety endpoints included death from all causes, major vascular complications, and major adverse cardiac event (MACE), i.e., a composite of cardiac death, myocardial reinfarction, target vessel revascularization (TVR), and heart failure. RESULTS: A total of 30 patients were finally included. Procedural success was achieved in 28 (93.3%) patients. No patients died during the study and no major vascular complications or MACE occurred during hospitalization. With the exception of one patient (3.3%) who underwent TVR three months after discharge, no patient encountered death (0.0%), major vascular complications (0.0%), or and other MACEs (0.0%) during the median follow-up of 16 months. CONCLUSION: The findings of the pilot study suggest that VCR has favorable feasibility and safety in patients with STEMI. Further larger randomized trials are required to evaluate the effectiveness of VCR in STEMI patients.

Identification and efficacy of glycine, serine and threonine metabolism in potentiating kanamycin-mediated killing of Edwardsiella piscicida.

We previously showed that glucose potentiated kanamycin to kill multidrug-resistant Edwardsiella piscicida through activation of the TCA cycle. However, whether other regulatory mechanism is involved requires further investigation. By quantitative proteomics technology, iTRAQ, we systematically mapped the altered proteins in the presence of glucose and identified 94 differentially expressed proteins. The analysis of the altered proteins by pathways, amino acid biosynthesis and metabolism were enriched. And the most significantly altered eight amino acids tyrosine, phenylalanine, valine, leucine, isoleucine, glycine, serine and threonine were investigated for their potentiation of kanamycin to kill EIB202, where glycine, serine and threonine showed the strongest efficacy than the others. The combinations of glycine and serine or glucose with glycine, serine or threonine had the best effects. Moreover, pyruvate dehydrogenase, α-ketoglutarate dehydrogenase and succinate dehydrogenase activities were increased as well as the proton motive force (PMF) and intracellular kanamycin. Finally, inhibitors that disrupt PMF production abolished the potentiation. These results shed light on the mechanism of how glucose promoting the amino acids biosynthesis and metabolism to potentiate kanamycin to kill antibiotic-resistant bacteria. More importantly, our results suggested that adjusting amino acid biosynthesis and metabolism might be a strategy to become phenotypic resistance to antibiotics in bacteria. SIGNIFICANCE: Tackling antibiotic resistance is an emerging issue in current years. Despite the efforts made toward developing new antibiotics, the progress is still lagged behind expectation. Novel strategies are required. The use of metabolite to revert antibiotic resistant is highly appreciated in recent years due to the less toxicity, more economic and high efficacy. As a continued study of our previous report on glucose potentiating kanamycin to kill antibiotic-resistant bacteria. The current study further expands the previous discovery on the mechanism of how glucose potentiate this effect. This result provides more basis on the action of glucose in reverting antibiotic resistance. And more importantly, we may derive more metabolites other than glucose to manage antibiotic resistance.

The depressed central carbon and energy metabolisms is associated to the acquisition of levofloxacin resistance in Vibrio alginolyticus.

The overuse and misuse of antibiotics lead to bacterial antibiotic resistance, challenging human health and intensive cultivation. It is especially required to understand for the mechanism of antibiotic resistance to control antibiotic-resistant pathogens. The present study characterized the differential proteome of levofloxacin-resistant Vibrio alginolyticus with the most advanced iTRAQ quantitative proteomics technology. A total of 160 proteins of differential abundance were identified, where 70 were decreased and 90 were increased. Further analysis demonstrated that crucial metabolic pathways like TCA cycle were significantly down-regulated. qRT-PCR analysis demonstrated the decreased gene expression of glycolysis/gluconeogenesis, the TCA cycle, and fatty acid biosynthesis. Moreover, Na(+)-NQR complex gene expression, membrane potential and the adenylate energy charge ratio were decreased, indicating that the decreased central carbon metabolism is associated to the acquisition of levofloxacin resistance. Therefore, the reduced central carbon and energy metabolisms form a characteristic feature as fitness costs of V. alginolyticus in resistance to levofloxacin. BIOLOGICAL SIGNIFICANCE: The overuse and misuse of antibiotics lead to bacterial antibiotic resistance, challenging human health and intensive cultivation. Understanding for the antibiotic resistance mechanisms is especially required to control these antibiotic-resistant pathogens. The present study characterized the differential proteome of levofloxacin-resistant Vibrio alginolyticus using the most advanced iTRAQ quantitative proteomics technology. A total of 160 differential abundance of proteins were identified with 70 decreases and 90 increases by liquid chromatography matrix assisted laser desorption ionization mass spectrometry. Most interestingly, crucial metabolic pathways such as the TCA cycle sharply fluctuated. This is the first report that the reduced central carbon and energy metabolisms form a characteristic feature as a mechanism of V. alginolyticus in resistance to levofloxacin.

Identification of ethanol tolerant outer membrane proteome reveals OmpC-dependent mechanism in a manner of EnvZ/OmpR regulation in Escherichia coli.

Ethanol is an efficient disinfectant, but long-term and wide usage of ethanol leads to microbial tolerance. Bacteria with the tolerance are widely identified. However, mechanisms of the tolerance are not elucidated. To explore the mechanisms of outer membrane (OM) proteins underlying ethanol tolerance in bacteria, functional proteomic methodologies were utilized to characterize OM proteins of E. coli suddenly exposed to 3.125% ethanol. Of eleven proteins altered significantly, seven were OM proteins, in which LamB, FadL and OmpC were up-regulated, and OmpT, OmpF, Tsx and OmpA were down-regulated. The alterations were validated using Western blot. Then, functional characterization of the altered abundance of OM proteins was investigated in gene-deleted and gene-complemented mutants cultured in 1.56-6.25% ethanol. Higher inhibiting rate was detected in ΔompC than ΔlamB and ΔompA, but no difference was found between Δtsx, ΔompF, ΔfadL or ΔompT and control. Furthermore, EnvZ/OmpR two-component signal transduction system, which regulates OmpC and OmpF expression, was determined to participate in the tolerance. Finally, our results show that absence of envZ, ompR or ompC and ompA led to elevated and reduced intracellular ethanol, respectively. These findings indicate EnvZ-dependent phosphotransfer signaling pathway of the OmpR-mediated expression of OmpC plays a crucial role in ethanol tolerance. BIOLOGICAL SIGNIFICANCE: Ethanol tolerance is an adaptation strategy of bacteria. In the present study, we used the proteomic approaches involving 2-DE and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) to determined outer membrane (OM) protein changes in E. coli K-12 after 2 h of 1/2 MIC of ethanol exposure. Under ethanol stress, seven differential OM proteins were found, which were validated by Western blot. Functions of these seven OM proteins were compared using their genetically modified strains. Furthermore, the role of EnvZ/OmpR two-component signal transduction system was identified in ethanol tolerance of E. coli. Finally, Loss of ompC, envZ or ompR increases intracellular ethanol, while absence of ompA reduces reversal effect. This is the first report of OM proteomics in E. coli exposed to ethanol. Our findings reveal an unknown OmpC-dependent mechanism of ethanol tolerance in a manner of EnvZ/OmpR regulation.

Alanine Enhances Aminoglycosides-Induced ROS Production as Revealed by Proteomic Analysis.

Metabolite-enabled killing of antibiotic-resistant pathogens by antibiotics is an attractive strategy to manage antibiotic resistance. Our previous study demonstrated that alanine or/and glucose increased the killing efficacy of kanamycin on antibiotic-resistant bacteria, whose action is through up-regulating TCA cycle, increasing proton motive force and enhancing antibiotic uptake. Despite the fact that alanine altered several metabolic pathways, other mechanisms could be potentially involved in alanine-mediated kanamycin killing of bacteria which remains to be explored. In the present study, we adopted proteomic approach to analyze the proteome changes induced by exogenous alanine. Our results revealed that the expression of three outer membrane proteins was altered and the deletion of nagE and fadL decreased the intracellular kanamycin concentration, implying their possible roles in mediating kanamycin transport. More importantly, the integrated analysis of proteomic and metabolomic data pointed out that alanine metabolism could connect to riboflavin metabolism that provides the source for reactive oxygen species (ROS) production. Functional studies confirmed that alanine treatment together with kanamycin could promote ROS production that in turn potentiates the killing of antibiotic-resistant bacteria. Further investigation showed that alanine repressed the transcription of antioxidant-encoding genes, and alanine metabolism to riboflavin metabolism connected with riboflavin metabolism through TCA cycle, glucogenesis pathway and pentose phosphate pathway. Our results suggest a novel mechanism by which alanine facilitates kanamycin killing of antibiotic-resistant bacteria via promoting ROS production.

C-Terminal Domain of Hemocyanin, a Major Antimicrobial Protein from Litopenaeus vannamei: Structural Homology with Immunoglobulins and Molecular Diversity.

Invertebrates rely heavily on immune-like molecules with highly diversified variability so as to counteract infections. However, the mechanisms and the relationship between this variability and functionalities are not well understood. Here, we showed that the C-terminal domain of hemocyanin (HMC) from shrimp Litopenaeus vannamei contained an evolutionary conserved domain with highly variable genetic sequence, which is structurally homologous to immunoglobulin (Ig). This domain is responsible for recognizing and binding to bacteria or red blood cells, initiating agglutination and hemolysis. Furthermore, when HMC is separated into three fractions using anti-human IgM, IgG, or IgA, the subpopulation, which reacted with anti-human IgM (HMC-M), showed the most significant antimicrobial activity. The high potency of HMC-M is a consequence of glycosylation, as it contains high abundance of α-d-mannose relative to α-d-glucose and N-acetyl-d-galactosamine. Thus, the removal of these glycans abolished the antimicrobial activity of HMC-M. Our results present a comprehensive investigation of the role of HMC in fighting against infections through genetic variability and epigenetic modification.

Progress in Therapies for Myocardial Ischemia Reperfusion Injury.

BACKGROUND: Experimental studies of acute myocardial infarction have revealed that up to half of the final infarct size may be due to reperfusion injury rather than the initial ischemic incident. Research over the past three decades has deepened our understanding of the molecular mechanisms underlying ischemic reperfusion injury and several therapeutic strategies to decrease the incidence and severity of reperfusion injury have been explored. OBJECTIVE: To discuss the promising therapies and future perspectives on methods to attenuate myocardial reperfusion injury. RESULTS: Existing therapies that address reperfusion can be divided into two major groups comprising nonpharmacological and pharmacological interventions. Myriad pharmacological and nonpharmacological approaches to reduce lethal reperfusion injury have been employed. Although many initial clinical studies were negative, more recent proof-of-concept clinical trials are promising. To date, the most encouraging results are with ischemic postconditioning, remote ischemic preconditioning, ANP, adenosine, cyclosporine and exenatide. CONCLUSION: Studies demonstrate that nonpharmacological and pharmacological conditioning can be used together as part of a multifaceted approach to improve clinical outcomes in patients with ischemic heart disease.

Outer membrane proteomics of kanamycin-resistant Escherichia coli identified MipA as a novel antibiotic resistance-related protein.

Antibiotic-resistant bacteria are a great threat to human health and food safety and there is an urgent need to understand the mechanisms of resistance for combating these bacteria. In the current study, comparative proteomic methodologies were applied to identify Escherichia coli K-12 outer membrane (OM) proteins related to kanamycin resistance. Mass spectrometry and western blotting results revealed that OM proteins TolC, Tsx and OstA were up-regulated, whereas MipA, OmpA, FadL and OmpW were down-regulated in kanamycin-resistant E. coli K-12 strain. Genetic deletion of tolC (ΔtolC-Km) led to a 2-fold decrease in the minimum inhibitory concentration (MIC) of kanamycin and deletion of mipA (ΔmipA-Km) resulted in a 4-fold increase in the MIC of kanamycin. Changes in the MICs for genetically modified strains could be completely recovered by gene complementation. Compared with the wild-type strain, the survival capability of ΔompA-Km was significantly increased and that of Δtsx-Km was significantly decreased. We further evaluated the role and expression of MipA in response to four other antibiotics including nalidixic acid, streptomycin, chloramphenicol and aureomycin, which suggested that MipA was a novel OM protein related to antibiotic resistance.

Systemic inflammation in patients with chronic obstructive pulmonary disease undergoing percutaneous coronary intervention.

BACKGROUND AND OBJECTIVE: Systemic inflammation plays an important role in both chronic obstructive pulmonary disease (COPD) and coronary artery disease (CAD). The purpose of the present study was to assess the association of high-sensitivity C-reactive protein (hs-CRP), a biomarker of systemic inflammation, with in-hospital outcomes in patients with COPD undergoing percutaneous coronary intervention (PCI). METHODS: A total of 378 patients with COPD who were treated with PCI from January 2007 through January 2012, were divided into two groups according to hs-CRP level at admission. Demographics, clinical, angiographic data and in-hospital outcomes were compared. RESULTS: Patients with elevated hs-CRP (≥3 mg/L) were more likely to be female and current smokers, had more severe airflow limitation, more hypertension, diabetes and cardiac dysfunction and had increased incidence of three-vessel disease and more type C lesions. Subjects with elevated hs-CRP were also less likely to have been prescribed with statins and B-blockers, perhaps. Rate of in-hospital composite major adverse cardiovascular events (MACEs) was higher (15.5% vs. 8.2%, P = 0.041) and hospital stay was longer (8.2 ± 2.0 vs. 7.5 ± 1.7 days, P < 0. 001) in patients with elevated hs-CRP. A combined analysis of MACE on the basis of airflow limitation and hs-CRP showed an exaggerated hazard ratio in the presence of both severe airflow limitation and elevated hs-CRP. In a multivariate analysis, elevated periprocedural hs-CRP was independently related with MACEs and hospital stay. CONCLUSIONS: Elevated periprocedural hs-CRP is independently and additively related with increased incidence of in-hospital adverse outcomes in COPD patients undergoing PCI.

Decreased expression of LamB and Odp1 complex is crucial for antibiotic resistance in Escherichia coli.

We previously revealed a negative regulation of LamB in chlortetracycline-resistant Escherichia coli strain. In the present study, we first showed that the negative regulation, which was characterized by decreased abundance of LamB with elevated growth of its gene-deleted mutant in medium with antibiotics, was a general response in resistance to different classes of antibiotics using 2-DE based proteomics or/and genetically gene-deletion mutant of LamB. Then, we revealed the interaction of LamB and Odp1 which catalyzes the overall conversion of pyruvate to acetyl-CoA and CO2, and found the decrease of the complex in antibiotic-resistant strains with a minimum inhibitory concentration dose-dependent manner. Further spectrofluorometry assay indicated that LamB served as a porin to influx an antibiotic. Finally, we showed that the decreased expression of LamB and Odp1 was detected in almost of all 34 multidrug-resistant strains, which suggested that LamB and Odp1 were biomarkers for identification of antibiotic-resistant E. coli. Our results indicated that the interaction of an outer membrane protein with an energy metabolic enzyme constructed an efficient pathway to resist antibiotics. These findings provide novel insights into the mechanisms of antibiotic resistance. BIOLOGICAL SIGNIFICANCE: Our data indicate that the negative regulation by LamB is widely detected in antibiotic-resistant E. coli. LamB serves as a porin to influx an antibiotic and is interacted with Odp1. The complex decreases in antibiotic-resistant strains with a MIC dose-dependent manner. Our findings indicate that interaction of outer membrane protein with energy metabolic enzyme constructs an efficient pathway to resist antibiotics and provides novel insights into the mechanisms of antibiotic resistance.

Characterization of outer membrane proteins of Escherichia coli in response to phenol stress.

Gram-negative bacteria are generally more tolerant to disinfectants than Gram-positive bacteria due to outer membrane (OM) barrier, but the tolerant mechanism is not well characterized. We have utilized comparative proteomic methodologies to characterize the OM proteins of E. coli K-12 K99+ in response to phenol stress and found that nine proteins were altered significantly. They were OM proteins OmpA, FadL, LamB, and OmpT, cytoplasmic-associated proteins AceA and EF-Tu, inner membrane protein AtpB, putative capsid protein Q8FewO, and unknown location protein Dps. They were reported here for the first time to be phenol-tolerant proteins. The alteration and functional characterization of the four OM proteins were further investigated using western blotting, genetically modified strains with gene deletion and gene complementation approaches. Our results characterized the functional OM proteins of E. coli in resistance to phenol, and provide novel insights into the mechanisms of bacterial disinfectant-tolerance and new drug targets for control of phenol-resistant bacteria.

Comparison of glucose-insulin-potassium and insulin-glucose as adjunctive therapy in acute myocardial infarction: a contemporary meta-analysis of randomised controlled trials.

BACKGROUND: There is conflicting evidence regarding two different insulin regimens for acute myocardial infarction (AMI), one focusing on delivering insulin ('insulin focus', glucose-insulin-potassium (GIK)) and one focusing on tight glycaemic control ('glycaemia focus', insulin-glucose). A longstanding controversy has focused on which strategy provides the greatest reduction in mortality. The aim of this study was to perform a meta-analysis of randomised controlled trials (RCTs) comparing GIK or insulin-glucose therapy versus standard therapy for AMI in the reperfusion era. METHODS: A MEDLINE/EMBASE/CENTRAL search was conducted of RCTs evaluating GIK or insulin-glucose as adjunctive therapy for AMI. The primary endpoint was all-cause mortality. The data were analysed with a random effect model. RESULTS: A total of 11 studies (including 23 864 patients) were identified, eight evaluating insulin focus with GIK and three evaluating glycaemia focus with insulin-glucose. Overall, insulin focus with GIK was not associated with a statistically significant effect on mortality (RR 1.07, 95% CI 0.89 to 1.29, p=0.487). Before the use of reperfusion, GIK also had no clear impact on mortality (RR 0.92, 95% CI 0.70 to 1.20, p=0.522). Pooled data from the three studies evaluating glycaemia focus showed that insulin-glucose did not reduce mortality in the absence of glycaemia control in patients with AMI with diabetes (RR 1.07, 95% CI 0.85 to 1.36, p=0.547). CONCLUSIONS: Current evidence suggests that GIK with insulin does not reduce mortality in patients with AMI. However, studies of glycaemia are inconclusive and it remains possible that glycaemic control is beneficial.

Attenuation of tumor necrosis factor-alpha elevation and improved heart function by postconditioning for 60 seconds in patients with acute myocardial infarction.

BACKGROUND: Postconditioning has been shown to reduce infarct size, ischemic/reperfusion injury and myocardial injury in patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI). This study tested the hypothesis that postconditioning attenuates the elevation of tumor necrosis factor-alpha (TNF-alpha) and improves heart function in patients with AMI after PCI. METHODS: A total of 75 patients were randomly assigned to 1 of 3 groups: the routine group (n = 26), in which no intervention was given at the onset of reperfusion; and the Postcon-30s (n = 25) or Postcon-60 s (n = 24) groups, in which 3 cycles of 30- or 60-second balloon deflation and inflation were repetitively performed. TNF-alpha serum concentration was measured by ELISA. Global and regional left ventricular systolic function was determined by echocardiography at 1 year. Thirty-four normal controls (NC) were enrolled in the study. RESULTS: The TNF-alpha concentration in patients with AMI was significantly elevated at baseline compared to controls (P < 0.01). Concentration levels increased in the routine and Postcon-30s, but not in Postcon-60s group at 7 days (P < 0.05). As for linear associations among the three groups, left ventricular ejection fraction (LVEF) and wall motion score index (WMSI) were ranked as follows: Postcon-60s > Postcon-30s > routine (P values all < 0.05, 65% vs. 57% vs. 52% and 1.10 vs. 1.27 vs. 1.53) after 1 year. More importantly, there was a significant relevance between the soluble TNF-alpha serum concentration at 7 days and LVEF or WMSI after 1 year (P values all < 0.0001). CONCLUSIONS: Postconditioning, in particular Postcon-60s was associated with long-term cardioprotective effects for inhibition of the inflammatory response and reperfusion injury. The soluble TNF-alpha serum concentration provided powerful prognostic information of global and regional left ventricular systolic function in patients with AMI.

A novel negative regulation mechanism of bacterial outer membrane proteins in response to antibiotic resistance.

Although some outer membrane (OM) proteins involved in antibiotic resistance have been previously reported, the OM proteins regulating chlortetracycline (CTC) resistance are largely unknown. In this study, we employed a subproteomics approach to identify altered OM proteins of Escherichia coli in response to CTC exposure. Upregulation of TolC and downregulation of LamB, FadL, OmpC, OmpT, and OmpW were found in E. coli strains exposed to CTC at a high concentration that was increased suddenly and at a half-minimum inhibitory concentration (MIC) that was kept constant in the culture medium. These changes in the level of protein expression were validated using Western blotting. In addition, the possible roles of these altered proteins and their regulation mechanisms in response to CTC exposure were investigated using genetically modified strains with gene deletion of these altered proteins. It was found that deletion of tolC, fadL, ompC, ompT, or ompW resulted in a decrease in the MICs and survival capabilities of the gene-deleted strains, whereas the absence of lamB led to an improvement of the two abilities. The downregulation of LamB expression in the CTC-resistant E. coli strain and the increased antibiotic resistance in its gene-deleted strain suggested a negative regulation mechanism in E. coli in response to CTC exposure. Meanwhile, the direction of the regulation pattern in response to CTC exposure was different from that in E. coli in response to exposure to other antibiotics. These findings uncover a novel antibiotic-resistant mechanism in which bacteria respond to exposure to antibiotics through alteration of the direction of regulation of OM proteins.

From proteome to genome for functional characterization of pH-dependent outer membrane proteins in Escherichia coli.

Proteomic technology is very powerful in identification of differentially expressed proteins. However, how to identify key proteins and distinguish them from others has been a question to be solved in functional proteomics. Utilizing 2-D gel based proteomic approach, we identified 11 differentially expressed outer membrane (OM) proteins involved in E. coli's response to pH change. The protein expression changes were validated by Western blotting. The function and roles of the differentially expressed proteins were further characterized using genetically modified strains with gene deletion of these altered OM proteins and gene complementation or overexpression approach. Among the differentially expressed proteins identified, OstA, TolC, OmpT, OmpP OmpC, Trak, OmpX, Dps, LamB, Tsx, FadL, OmpW, and OmpF were characterized as pH-related OM proteins. Out of these OM proteins, TolC, OmpC, OmpX, and LamB may play critical roles in pH-regulation in E. coli. Using death-rescuing assay developed in house, we found that OmpC, LamB, FadL, OmpX, OmpW, and OmpF, LamB, FadL, and OmpW functioned in a TolC-independent pathway, whereas OmpF, Tsx and OmpC, OmpX, and Tsx might share the same pathway with TolC at the extreme acid or base condition. The information obtained from this study provides novel insight into mechanisms of pH response in E. coli. Our results also demonstrate the importance and efficiency of functional characterization of differentially expressed proteins at different molecular levels in identification of key target proteins and pathways involved in E. coli' s response to pH change.

Identification and network of outer membrane proteins regulating streptomysin resistance in Escherichia coli.

Bacterial Outer membrane (OM) proteins involved in antibiotic resistance have been reported. However, little is known about the OM proteins and their interaction network regulating streptomycin (SM) resistance. In the present study, a subproteomic approach was utilized to characterize OM proteins of Escherichia coli with SM resistance. TolC, OmpT and LamB were found to be up-regulated, and FadL, OmpW and a location-unknown protein Dps were down-regulated in the SM-resistant E. coli strain. These changes at the level of protein expression were validated using Western blotting. The possible roles of the altered proteins involved in the SM resistance were investigated using genetic modified strains with the deletion of these altered genes. It is found that decreased and elevated minimum inhibitory concentrations and survival capabilities of the gene deleted strains and their resistant strains, Delta tolC, Delta ompT, Delta dps, Delta tolC-R, Delta ompT-R, Delta dps-R and Delta fadL-R, were correlated with the changes of TolC, OmpT, Dps and FadL at the protein expression levels detected by 2-DE gels, respectively. The results may suggest that these proteins are the key OM proteins and play important roles in the regulation of SM resistance in E. coli. Furthermore, an interaction network of altered OM proteins involved in the SM resistance was proposed in this report. Of the six altered proteins, TolC may play a central role in the network. These findings may provide novel insights into mechanisms of SM resistance in E. coli.

Proteomic analysis of nalidixic acid resistance in Escherichia coli: identification and functional characterization of OM proteins.

The worldwide emergence of antibiotic-resistant bacteria poses a serious threat to human health. To understand the mechanisms of the resistance is extremely important to the control of these bacteria. In the current study, proteomic methodologies were utilized to characterize OM proteome of Escherichia coli with nalidixic acid (NA) resistance. The OM proteins TolC, OmpT, OmpC and OmpW were found to be up-regulated, and FadL was down-regulated in the NA-resistant E. coli strains. The changes at the level of protein expression were validated using Western blotting. Furthermore, the possible roles these altered proteins played in regulation of NA resistance were investigated using genetically modified strains with the deletion of these genes. The results obtained from functional characterization of these genetically modified strains suggest that TolC and OmpC may play more important roles in the control of NA resistance than other OM proteins identified. To gain better understanding of the mechanisms of NA resistance, we also characterized the role of the two-component system EnvZ/OmpR which is responsible for the regulation of OmpC and OmpF expression in response to NA resistance using their genetically modified strains. Our results suggest that OmpF and the EnvZ/OmpR are also important participants of the pathways regulating the NA resistance of E. coli.

Downregulation of Tsx and OmpW and upregulation of OmpX are required for iron homeostasis in Escherichia coli.

Upregulation of outer membrane (OM) proteins was systematically investigated in response to poor iron availability in the host and natural environments, but downregulation of OM proteins was ill-defined in this response. We utilized proteomic methodologies to characterize altered OM proteins in the sarcosine-insoluble fraction of Escherichia coli K12 cultured in LB medium with iron limitation. Notably, three novel proteins, Tsx, OmpW, and OmpX, related to iron homeostasis were identified; Tsx and OmpW were downregulated, and OmpX was upregulated. These alterations were functionally validated with the use of gene overexpression and deletion methods. Of the two downregulated proteins, Tsx was more sensitive to an iron-deficient environment than OmpW. In addition, the significantly negative correlation between Tsx with OmpW was achieved when overexpressed strains were used. These findings strongly indicate that the downregulation of Tsx and OmpW and the upregulation of OmpX are required for iron homeostasis in E. coli.

Identification and antibody-therapeutic targeting of chloramphenicol-resistant outer membrane proteins in Escherichia coli.

Bacterial resistance to an antibiotic may result from survival in a suddenly strong antibiotic or in sub-minimum inhibitory concentration of the drug. Their shared proteins responsible for the resistance should be potential targets for designing new drugs to inhibit the growth of the antibiotic-resistant bacteria. In the current study, comparative proteomic methodologies were used for identification of sharedly altered outer membrane proteins (OM proteins) that are responsible for chloramphenical (CAP)-resistant Escherichia coli and for survival in medium with suddenly strong CAP treatment. Six differential OM proteins and another protein with unknown location were determined to be sharedly CAP-resistant-related proteins with the use of 2-DE/MS, Western blotting and gene mutant methods, in which TolC, OmpT, OmpC, and OmpW were critically altered proteins and potential targets for designing of the new drugs. Furthermore, a novel method of specific antibody combating bacterial growth was developed on these OM proteins. Only anti-TolC showed a very significant inhibition on bacterial growth in medium with CAP when antisera to TolC, OmpC, OmpT, and OmpW were separately utilized. The growth of CAP-resistant E. coli and its original strain was completely inhibited when they bound with anti-TolC and survived in 1/8 MIC of CAP. This observed result is basically the same to the finding that DeltatolC was survived in the same concentration of the antibiotic. Our study demonstrates that the enhancement of expression of antibody target with antibiotic could be very effective approach compared to using a drug alone, which highlights a potential way for treatment of infection by antibiotic-resistant bacteria.

Systematic identification of the subproteome of Escherichia coli cell envelope reveals the interaction network of membrane proteins and membrane-associated peripheral proteins.

Membrane proteins of Gram-negative bacteria are key molecules that interface the cells with the environment. Despite recent proteomic identification of numerous oligomer proteins in the Escherichia coli cell envelope, the protein complex of E. coli membrane proteins and their peripherally associated proteins remain ill-defined. In the current study, we systematically analyze the subproteome of E. coli cell envelope enriched in sarcosine-insoluble fraction (SIF) and sarcosine-soluble fraction (SSF) by using proteomic methodologies. One hundred and four proteins out of 184 spots on 2D electrophoresis gels are identified, which includes 31 outer membrane proteins (OMPs). Importantly, our further proteomic studies reveal a number of previously unrecognized membrane-interacting protein complexes, such as the complex consisting of OmpW and fumarate reductase. This established complete proteomic profile of E. coli envelope also sheds new insight into the function(s) of E. coli outer envelope.