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1.
J Microbiol Immunol Infect ; 57(1): 175-183, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38065768

ABSTRACT

BACKGROUND: Children with allergic rhinitis (AR) have substantially more acute rhinosinusitis than children without AR. We evaluated whether intranasal corticosteroids (INCS), second-generation antihistamines (SGH), and/or intranasal antihistamines (INH) for AR affect acute rhinosinusitis in children with AR aged 2-18 years. METHODS: By using the National Health Research Institutes Database 2005 of Taiwan, a cohort of patients with AR aged 2-18 years treated with AR medications between 2002 and 2018 was made, within which a nested case-control study was performed. Risk settings for acute rhinosinusitis cases matched controls for age, sex, and comorbidities. Current users of INCS, INH, and/or SGH were compared with remote and recent users of any AR medications and current users of INCS with and without SGH were compared with current users of SGH. RESULTS: Current users of SGH and/or INCS had a higher risk of acute rhinosinusitis than remote users of AR drugs, and current users of SGH had a higher risk of acute rhinosinusitis than recent users; however, no difference in the risk of acute rhinosinusitis was found between current users of INCS and recent users of AR drugs. Current users of INCS with and without SGH had a lower risk of acute rhinosinusitis than current users of SGH alone. CONCLUSIONS: Treatment of INCS with and without SGH diminished the risk of acute rhinosinusitis compared with treatment using SGH alone. Adequate INCS treatment for patients with AR is important to reduce the incidence of acute rhinosinusitis.


Subject(s)
Rhinitis, Allergic , Rhinosinusitis , Child , Humans , Case-Control Studies , Rhinitis, Allergic/drug therapy , Adrenal Cortex Hormones/therapeutic use , Histamine Antagonists/therapeutic use
2.
Heliyon ; 9(8): e18825, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37600395

ABSTRACT

Liquid desiccant technology is an energy-efficient substitute for technologies that are conventionally applied for temperature and humidity control; however, innovative desiccant solutions have not been extensively explored in terms of their performance and feasibility. This work aimed to investigate desiccant solutions with moisture sorption analysis technically and economically. Various conditions of temperature and humidity were tested in a climatic chamber and the moisture absorption and desorption capacity, thermo-chemical energy storage capacity, and cost of conventional and innovative desiccant solutions were assessed by experiment. Calcium chloride showed the highest moisture desorption capacity (0.3113 gH2O/gsol in the climatic chamber at 50 °C and 25% RH) and the lowest cost, despite its low moisture absorption capacity. Ionic liquids show high moisture absorption capacity (as high as 0.429 gH2O/gsol in the climatic chamber at 25 °C and 90% RH) and could be used as additives (in which a maximum increase of 84.1% was observed for moisture absorption capacity due to the addition of ionic liquids), and thus, they are promising substitutes for conventional desiccant solutions. As solutions for better performance under various conditions were identified, the study will advance liquid desiccant technology.

3.
Nucleic Acids Res ; 51(11): 5603-5620, 2023 06 23.
Article in English | MEDLINE | ID: mdl-37140034

ABSTRACT

Dynamic protein gradients are exploited for the spatial organization and segregation of replicated chromosomes. However, mechanisms of protein gradient formation and how that spatially organizes chromosomes remain poorly understood. Here, we have determined the kinetic principles of subcellular localizations of ParA2 ATPase, an essential spatial regulator of chromosome 2 segregation in the multichromosome bacterium, Vibrio cholerae. We found that ParA2 gradients self-organize in V. cholerae cells into dynamic pole-to-pole oscillations. We examined the ParA2 ATPase cycle and ParA2 interactions with ParB2 and DNA. In vitro, ParA2-ATP dimers undergo a rate-limiting conformational switch, catalysed by DNA to achieve DNA-binding competence. This active ParA2 state loads onto DNA cooperatively as higher order oligomers. Our results indicate that the midcell localization of ParB2-parS2 complexes stimulate ATP hydrolysis and ParA2 release from the nucleoid, generating an asymmetric ParA2 gradient with maximal concentration toward the poles. This rapid dissociation coupled with slow nucleotide exchange and conformational switch provides for a temporal lag that allows the redistribution of ParA2 to the opposite pole for nucleoid reattachment. Based on our data, we propose a 'Tug-of-war' model that uses dynamic oscillations of ParA2 to spatially regulate symmetric segregation and positioning of bacterial chromosomes.


Subject(s)
Adenosine Triphosphatases , Vibrio cholerae , Adenosine Triphosphatases/chemistry , Adenosine Triphosphatases/metabolism , Adenosine Triphosphate/metabolism , Bacterial Proteins/metabolism , Chromosome Segregation , Chromosomes, Bacterial/metabolism , DNA , Vibrio cholerae/genetics , Vibrio cholerae/metabolism
4.
Article in English | WPRIM (Western Pacific) | ID: wpr-988693

ABSTRACT

@#Introduction: Advancement in digital technology opens new doors for food safety auditors when it comes to performing food safety audits. Surge of Covid cases since year 2020 has seen an unprecedented switch to remote auditing by the Food Safety and Quality Programme under the arm of Ministry of Health in Malaysia. Methods: This paper presents the use of QGIS, an open-source cross-platform for geographic information system (GIS) to store, manage and visualise 2 types of data, i.e. real time data collected via a mobile device using QField, an open-source mobile application and also fixed data retrieved from existing database. New data from obtained from field sampling and surveillance presents updated information for food safety auditing and enforcement purposes. A total of 4972 datasets were obtained from the Ministry of Health’s Food Safety and Quality Division database on food factories from all 13 states and 3 federal territories in Malaysia. These datasets were transformed and stored into QGIS point layer for performing data classification analysis on clustering of HACCP, GMP and MeSTI certifications. Results: The Penang state has the most HACCP certified companies in fish and fish product category, Selangor is the highest for confectionery industry and Sabah for food services. The general output of mobile GIS provides a big picture of distribution of food safety certifications in Malaysia while more specific adoption of QField can assist in effective field work planning for enforcement officers and auditors leading to cost calculation via information on location, distance and time. Conclusion: QGIS application for spatial and temporal visualisation of data benefits the food safety auditing in Malaysia

5.
Biomedicines ; 10(5)2022 Apr 28.
Article in English | MEDLINE | ID: mdl-35625759

ABSTRACT

Cholangiocarcinoma (CCA) is the second most common primary liver cancer with poor prognosis. The deregulation of a lot of oncogenic signaling molecules, such as receptor tyrosine kinases (RTKs), has been found to be associated with CCA progression. However, RTKs-based target therapy showed limited improvement suggesting a need to search for alternative targets for preventing CCA progression. To address this issue, we screened the oncogenic signal molecules upregulated in surgical tissues of CCAs. Interestingly, over-expression of hydrogen peroxide inducible clone-5 (Hic-5) coupled with over-activation of Src, AKT, JNK were observed in 50% of the cholangiocarcinoma with metastatic potential. To investigate whether these molecules may work together to trigger metastatic signaling, their up-and-down relationship was examined in a well-established cholangiocarcinoma cell line, HuCCT1. Src inhibitors PP1 (IC50, 13.4 µM) and dasatinib (IC50, 0.1 µM) significantly decreased both phosphorylated AKT (phosphor-AKT Thr450) and Hic-5 in HuCCT1. In addition, a knockdown of Hic-5 effectively suppressed activation of Src, JNK, and AKT. These implicated a positive cross-talk occurred between Hic-5 and Src for triggering AKT activation. Further, depletion of Hic-5 and inhibition of Src suppressed HuccT1 cell migration in a dose-dependent manner. Remarkably, prior transfection of Hic-5 siRNA for 24 h followed by treatment with PP1 or dasatinib for 24 h resulted in additive suppression of HuCCT1 migration. This suggested that a promising combinatory efficacy can be achieved by depletion of Hic-5 coupled with inhibition of Src. In the future, target therapy against CCA progression by co-targeting Hic-5 and Src may be successfully developed in vivo.

6.
Front Pediatr ; 10: 865099, 2022.
Article in English | MEDLINE | ID: mdl-35547549

ABSTRACT

Objectives: We described the etiology of severe pneumonia in children during the height of the COVID-19 pandemic in Malaysia and compared the clinical features of severe SARS-CoV-2 to other respiratory viruses. Methods: This retrospective study included all children aged 12 years and below hospitalized with severe pneumonia in Negeri Sembilan, Malaysia, between 1 April 2021 and 31 October 2021. We extracted demographic and clinical data and used logistic regression to examine risk factors associated with severe SARS-CoV-2 or other viral pneumonia. Results: A total of 111 children were included. The median age was 15 months. Human rhinovirus/enterovirus, SARS-CoV-2 and respiratory syncytial virus were the most common etiology of severe pneumonia. Codetection of >1 viral pathogen was present in 14 (12.6%) patients. Children with severe COVID-19 presented early in the course of illness and had lower rates of pediatric intensive care admission. The presence of sick contact with an adult was a predictor for SARS-CoV-2, whereas adventitious breath sounds were predictive of other respiratory viruses. Conclusions: The etiology of severe pneumonia in children evolved with the epidemic curve of COVID-19 and school closures. Children with severe pneumonia due to SARS-CoV-2 experienced a milder clinical course when compared to other respiratory viruses.

7.
Microbiol Resour Announc ; 11(1): e0104021, 2022 Jan 20.
Article in English | MEDLINE | ID: mdl-34989616

ABSTRACT

This paper reports on the whole-genome sequencing of a streptomycin-resistant Mycobacterium tuberculosis strain that was isolated from a patient with pulmonary tuberculosis in Sabah state of Malaysian Borneo. The strain belongs to the EAI2-Manila family of lineage 1 and is clustered with M. tuberculosis strains from the Philippines, India, and Taiwan.

8.
Energy (Oxf) ; 244: 122709, 2022 Apr 01.
Article in English | MEDLINE | ID: mdl-34840405

ABSTRACT

The spread of the coronavirus SARS-CoV-2 affects the health of people and the economy worldwide. As air transmits the virus, heating, ventilation and air-conditioning (HVAC) systems in buildings, enclosed spaces and public transport play a significant role in limiting the transmission of airborne pathogens at the expenses of increased energy consumption and possibly reduced thermal comfort. On the other hand, liquid desiccant technology could be adopted as an air scrubber to increase indoor air quality and inactivate pathogens through temperature and humidity control, making them less favourable to the growth, proliferation and infectivity of microorganisms. The objectives of this study are to review the role of HVAC in airborne viral transmission, estimate its energy penalty associated with the adoption of HVAC for transmission reduction and understand the potential of liquid desiccant technology. Factors affecting the inactivation of pathogens by liquid desiccant solutions and possible modifications to increase their heat and mass transfer and sanitising characteristics are also described, followed by an economic evaluation. It is concluded that the liquid desiccant technology could be beneficial in buildings (requiring humidity control or moisture removal in particular when viruses are likely to present) or in high-footfall enclosed spaces (during virus outbreaks).

10.
Public Health Rep ; 136(5): 595-602, 2021.
Article in English | MEDLINE | ID: mdl-33541227

ABSTRACT

OBJECTIVES: Inaccuracies in cause-of-death information in death certificates can reduce the validity of national death statistics and result in poor targeting of resources to reduce morbidity and mortality in people with HIV. Our objective was to measure the sensitivity, specificity, and agreement between multiple causes of deaths from death certificates obtained from the National Death Index (NDI) and causes determined by expert physician review. METHODS: Physician specialists determined the cause of death using information collected from the medical records of 50 randomly selected HIV-infected people who died in San Francisco from July 1, 2016, through May 31, 2017. Using expert review as the gold standard, we measured sensitivity, specificity, and agreement. RESULTS: The NDI had a sensitivity of 53.9% and a specificity of 66.7% for HIV deaths. The NDI had a moderate sensitivity for non-AIDS-related infectious diseases and non-AIDS-related cancers (70.6% and 75.0%, respectively) and high specificity for these causes (100.0% and 94.7%, respectively). The NDI had low sensitivity and high specificity for substance abuse (27.3% and 100.0%, respectively), heart disease (58.3% and 86.8%, respectively), hepatitis B/C (33.3% and 97.7%, respectively), and mental illness (50.0% and 97.8%, respectively). The measure of agreement between expert review and the NDI was lowest for HIV (κ = 0.20); moderate for heart disease (κ = 0.45) and hepatitis B/C (κ = 0.40); high for non-AIDS-related infectious diseases (κ = 0.76) and non-AIDS-related cancers (κ = 0.72); and low for all other causes of death (κ < 0.35). CONCLUSIONS: Our findings support education and training of health care providers to improve the accuracy of cause-of-death information on death certificates.


Subject(s)
Cause of Death/trends , Data Collection/standards , Death Certificates , HIV Infections/epidemiology , Adult , Aged , Comorbidity , Female , HIV Infections/mortality , HIV Infections/transmission , Humans , Male , Middle Aged , San Francisco/epidemiology , Sensitivity and Specificity
11.
Appl Environ Microbiol ; 87(6)2021 02 26.
Article in English | MEDLINE | ID: mdl-33452021

ABSTRACT

The alphaproteobacterium Zymomonas mobilis exhibits extreme ethanologenic physiology, making this species a promising biofuel producer. Numerous studies have investigated its biology relevant to industrial applications and mostly at the population level. However, the organization of single cells in this industrially important polyploid species has been largely uncharacterized. In the present study, we characterized basic cellular behavior of Z. mobilis strain Zm6 under anaerobic conditions at the single-cell level. We observed that growing Z. mobilis cells often divided at a nonmidcell position, which contributed to variant cell size at birth. However, the cell size variance was regulated by a modulation of cell cycle span, mediated by a correlation of bacterial tubulin homologue FtsZ ring accumulation with cell growth. The Z. mobilis culture also exhibited heterogeneous cellular DNA content among individual cells, which might have been caused by asynchronous replication of chromosome that was not coordinated with cell growth. Furthermore, slightly angled divisions might have resulted in temporary curvatures of attached Z. mobilis cells. Overall, the present study uncovers a novel bacterial cell organization in Z. mobilisIMPORTANCE With increasing environmental concerns about the use of fossil fuels, development of a sustainable biofuel production platform has been attracting significant public attention. Ethanologenic Z. mobilis species are endowed with an efficient ethanol fermentation capacity that surpasses, in several respects, that of baker's yeast (Saccharomyces cerevisiae), the most-used microorganism for ethanol production. For development of a Z. mobilis culture-based biorefinery, an investigation of its uncharacterized cell biology is important, because bacterial cellular organization and metabolism are closely associated with each other in a single cell compartment. In addition, the current work demonstrates that the polyploid bacterium Z. mobilis exhibits a distinctive mode of bacterial cell organization, likely reflecting its unique metabolism that does not prioritize incorporation of nutrients for cell growth. Thus, another significant result of this work is to advance our general understanding in the diversity of bacterial cell architecture.


Subject(s)
Zymomonas , Cell Division , DNA, Bacterial , Ethanol/metabolism , Microscopy, Electron , Zymomonas/cytology , Zymomonas/genetics , Zymomonas/ultrastructure
12.
Qual Manag Health Care ; 30(1): 61-68, 2021.
Article in English | MEDLINE | ID: mdl-33306657

ABSTRACT

BACKGROUND AND OBJECTIVES: In response to the COVID-19 pandemic outbreak and to ensure the safety of epidemic prevention in the hospital, the hospital has established mitigation strategies in advance including risk assessment and effect analysis to control hospital visitors and accompanying persons. The study aims to assess the effectiveness of mitigation strategies implemented to effectively prevent the invasion and spread of the virus. METHOD: Conduct a status analysis in accordance with the Healthcare Failure Mode and Effect Analysis (HFMEA) 4-step model, construct a response workflow, confirm the failure mode and potential causes, perform hazard matrix analysis and decision tree analysis, and formulate risk control management measures. RESULTS: For the 4 main processes and 9 subprocesses of the accompanying carers and contract caregivers entering the hospital, 26 potential failure modes and 42 potential causes of failure were analyzed. Following implementing improvement measures including strategies targeting the accompanying person, mitigation workflow failure rates decreased from 42 to 13 items, the pass rate for the maximum body temperature cutoff increased from 53.1% to 90.8%, and the compliance rate of hand washing increased from 89.5% to 100%. CONCLUSION: The HFMEA model can effectively implement preventive risk assessment and workflow management of high-risk medical procedures. The model can adjudicate the health of hospital visitors during the epidemic/pandemic, provide epidemic/pandemic education training and preventive measure health education guidance for hospital visits, and improve their epidemic prevention cognition. When combined, these strategies can prevent nosocomial infection to achieve the best anti-epidemic effect.


Subject(s)
COVID-19/prevention & control , Cross Infection/prevention & control , Healthcare Failure Mode and Effect Analysis , Visitors to Patients , COVID-19/transmission , Caregivers , Cross Infection/transmission , Hand Disinfection , Healthcare Failure Mode and Effect Analysis/methods , Healthcare Failure Mode and Effect Analysis/organization & administration , Hospitals, Urban/organization & administration , Humans , Models, Organizational , Organizational Policy , Risk Assessment , Taiwan/epidemiology
13.
Data Brief ; 33: 106388, 2020 Dec.
Article in English | MEDLINE | ID: mdl-33102655

ABSTRACT

In 2019, 10 million new cases of tuberculosis have been reported worldwide. Our data reports genetic analyses of a Mycobacterium tuberculosis strain SBH321 isolated from a 31-year-old female with pulmonary tuberculosis. The genomic DNA of the strain was extracted from pure culture and subjected to sequencing using Illumina platform. M. tuberculosis strain SBH321 consists of 4,374,895 bp with G+C content of 65.59%. The comparative analysis by SNP-based phylogenetic analysis using maximum-likelihood method showed that our strain belonging to sublineage of the Ural family of Europe-America-Africa lineage (Lineage 4) and clustered with M. tuberculosis strain OFXR-4 from Taiwan. The whole genome sequence is deposited at DDBJ/ENA/GenBank under the accession WCJH00000000 (SRR10230353).

14.
Microbiol Resour Announc ; 9(2)2020 Jan 09.
Article in English | MEDLINE | ID: mdl-31919173

ABSTRACT

This is a report on the whole-genome sequence of Mycobacterium tuberculosis strain SBH163, which was isolated from a patient in the Malaysian Borneo state of Sabah. This report provides insight into the molecular characteristics of an M. tuberculosis Beijing genotype strain related to strains from Russia and South Africa.

15.
Data Brief ; 26: 104445, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31534995

ABSTRACT

A Mycobacterium tuberculosis strain SBH162 was isolated from a 49-year-old male with pulmonary tuberculosis. GeneXpert MDR/RIF identified the strain as rifampicin-resistant M. tuberculosis. The whole genome sequencing was performed using Illumina HiSeq 4000 system to further investigate and verify the mutation sites of the strain through genetic analyses namely variant calling using bioinformatics tools. The de novo assembly of genome generated 100 contigs with N50 of 156,381bp. The whole genome size was 4,343,911 bp with G + C content of 65.58% and consisted of 4,306 predicted genes. The mutation site, S450L, for rifampicin resistance was detected in the rpoB gene. Based on the phylogenetic analysis using the Maximum Likelihood method, the strain was identified as belonging to the Europe America Africa lineage (Lineage 4). The genome dataset has been deposited at DDBJ/ENA/GenBank under the accession number SMOE00000000.

16.
Am J Prev Med ; 54(1): 133-143, 2018 Jan.
Article in English | MEDLINE | ID: mdl-29254551

ABSTRACT

CONTEXT: Globally, uptake of health screening in men remains low and the effectiveness of interventions to promote screening uptake in men is not well established. This review aimed to determine the effectiveness of interventions in improving men's uptake of and intention to undergo screening, including interventions using information and communication technology and a male-sensitive approach. EVIDENCE ACQUISITION: Studies were sourced from five electronic databases (October 2015), experts, and references of included studies. This study included RCTs or cluster RCTs that recruited men and reported uptake of or intention to undergo screening. Two researchers independently performed study selection, appraisal, and data extraction. The interventions were grouped into those that increase uptake and those that promote informed decision making. They were further sub-analyzed according to types of intervention, male-sensitive, and web- and video-based interventions. The analysis was completed in December 2016. EVIDENCE SYNTHESIS: This review included 58 studies. Most studies were on prostate cancer (k=31) and HIV (k=11) screening. Most of the studies had low methodologic quality (79.3%) and after excluding them from the analysis, one study found that educational intervention (which was also male-sensitive) was effective in improving men's intention to screen (risk ratio=1.36, 95% CI=1.23, 1.50, k=1) and partner educational intervention increased men's screening uptake (risk ratio=1.77, 95% CI=1.48, 2.12, k=1). Video-based educational interventions reduced prostate cancer screening uptake (risk ratio=0.89, 95%CI=0.80, 0.99, k=1) but web-based interventions did not change men's screening intention or uptake. CONCLUSIONS: This review highlights the need to conduct more robust studies to provide conclusive evidence on the effectiveness of different interventions to improve men's screening behavior.


Subject(s)
Decision Making , Early Detection of Cancer/methods , Intention , Prostatic Neoplasms/diagnosis , Humans , Male , Risk
17.
Int J STD AIDS ; 29(2): 135-146, 2018 02.
Article in English | MEDLINE | ID: mdl-28728525

ABSTRACT

The objective was to examine gender differences in causes of death using the San Francisco HIV/AIDS and death registries. Data from San Francisco residents diagnosed with HIV/AIDS who died from 1996 to 2013 were analyzed. Age, race/ethnicity, year, and gender-adjusted standardized mortality ratios and Poisson 95% confidence intervals were calculated for underlying causes of death. Among the 6268 deaths, deaths attributed to drug use, mental disorders due to substance use, cerebrovascular disease, chronic obstructive pulmonary disease, renal disease, and septicemia were more likely among women than among men. Compared to the California population, women had elevated standardized mortality ratios for drug overdose (25.37), mental disorders due to substance abuse (27.21), cerebrovascular disease (2.83), chronic obstructive pulmonary disease (7.37), heart disease (2.37), and liver disease (5.54), and these were higher than the standardized mortality ratios for the men in our study. Men, but not women, had elevated standardized mortality ratios for suicide (2.70), undetermined intent (3.88), renal disease (2.29), and non-AIDS cancer (1.68) compared to population rates. Continued efforts to reduce HIV-related illnesses and an increased emphasis on diagnosing and treating preventable causes of death, including substance use, heart disease, and mental health disorders, are needed as part of comprehensive HIV care.


Subject(s)
AIDS-Related Opportunistic Infections/mortality , Acquired Immunodeficiency Syndrome/complications , Acquired Immunodeficiency Syndrome/mortality , Cause of Death , Acquired Immunodeficiency Syndrome/drug therapy , Adolescent , Adult , Aged , Anti-HIV Agents/therapeutic use , Antiretroviral Therapy, Highly Active , Ethnicity/statistics & numerical data , Female , Humans , Male , Middle Aged , Neoplasms/mortality , Risk Factors , San Francisco/epidemiology , Sex Distribution , Substance Abuse, Intravenous/mortality , Young Adult
18.
Plasmid ; 91: 37-41, 2017 05.
Article in English | MEDLINE | ID: mdl-28322855

ABSTRACT

Bacterial plasmid and chromosome segregation systems ensure that genetic material is efficiently transmitted to progeny cells. Cell-based studies have shed light on the dynamic nature and the molecular basis of plasmid partition systems. In vitro reconstitutions, on the other hand, have proved to be an invaluable tool for studying the minimal components required to elucidate the mechanism of DNA segregation. This allows us to gain insight into the biological and biophysical processes that enable bacterial cells to move and position DNA. Here, we review the reconstitutions of plasmid partition systems in cell-free reactions, and discuss recent work that has begun to challenge long standing models of DNA segregation in bacteria.


Subject(s)
Bacillus thuringiensis/genetics , DNA Replication , DNA, Bacterial/genetics , Escherichia coli/genetics , Plasmids/chemistry , Actins/chemistry , Bacillus thuringiensis/metabolism , Biological Transport , Chromosome Segregation , Chromosomes, Bacterial , DNA, Bacterial/metabolism , Escherichia coli/metabolism , Molecular Mimicry , Plasmids/metabolism , Tubulin/chemistry
19.
Mol Cell ; 63(6): 939-50, 2016 09 15.
Article in English | MEDLINE | ID: mdl-27618490

ABSTRACT

In bacteria, RNA polymerase (RNAP) initiates transcription by synthesizing short transcripts that are either released or extended to allow RNAP to escape from the promoter. The mechanism of initial transcription is unclear due to the presence of transient intermediates and molecular heterogeneity. Here, we studied initial transcription on a lac promoter using single-molecule fluorescence observations of DNA scrunching on immobilized transcription complexes. Our work revealed a long pause ("initiation pause," ∼20 s) after synthesis of a 6-mer RNA; such pauses can serve as regulatory checkpoints. Region sigma 3.2, which contains a loop blocking the RNA exit channel, was a major pausing determinant. We also obtained evidence for RNA backtracking during abortive initial transcription and for additional pausing prior to escape. We summarized our work in a model for initial transcription, in which pausing is controlled by a complex set of determinants that modulate the transition from a 6- to a 7-nt RNA.


Subject(s)
DNA-Directed RNA Polymerases/genetics , Escherichia coli Proteins/genetics , Escherichia coli/genetics , RNA, Messenger/genetics , Transcription, Genetic , Base Sequence , DNA-Directed RNA Polymerases/metabolism , Escherichia coli/metabolism , Escherichia coli Proteins/metabolism , Fluorescence Resonance Energy Transfer , Lac Operon , Nucleic Acid Synthesis Inhibitors/pharmacology , Promoter Regions, Genetic , RNA, Bacterial/genetics , RNA, Bacterial/metabolism , RNA, Messenger/antagonists & inhibitors , RNA, Messenger/biosynthesis , Rifampin/pharmacology , Single Molecule Imaging/methods , Time Factors
20.
Proc Natl Acad Sci U S A ; 113(11): E1479-88, 2016 Mar 15.
Article in English | MEDLINE | ID: mdl-26884160

ABSTRACT

The Escherichia coli Min system self-organizes into a cell-pole to cell-pole oscillator on the membrane to prevent divisions at the cell poles. Reconstituting the Min system on a lipid bilayer has contributed to elucidating the oscillatory mechanism. However, previous in vitro patterns were attained with protein densities on the bilayer far in excess of those in vivo and failed to recapitulate the standing wave oscillations observed in vivo. Here we studied Min protein patterning at limiting MinD concentrations reflecting the in vivo conditions. We identified "burst" patterns--radially expanding and imploding binding zones of MinD, accompanied by a peripheral ring of MinE. Bursts share several features with the in vivo dynamics of the Min system including standing wave oscillations. Our data support a patterning mechanism whereby the MinD-to-MinE ratio on the membrane acts as a toggle switch: recruiting and stabilizing MinD on the membrane when the ratio is high and releasing MinD from the membrane when the ratio is low. Coupling this toggle switch behavior with MinD depletion from the cytoplasm drives a self-organized standing wave oscillator.


Subject(s)
Adenosine Triphosphatases/metabolism , Cell Cycle Proteins/metabolism , Cell Membrane/metabolism , Escherichia coli Proteins/metabolism , Adenosine Triphosphatases/genetics , Cell Cycle Proteins/genetics , Cell-Free System , Cytoplasm/metabolism , Escherichia coli Proteins/genetics , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Image Processing, Computer-Assisted , Lipid Bilayers , Microscopy, Fluorescence , Protein Multimerization
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