oriC

oriC
  • 文章类型: Journal Article
    需要成功实施有效的干预措施才能产生影响。存在两种基于理论的措施来衡量实施策略的有效性并监测实施进度。标准化保证发展问卷(NoMAD)探讨了四个核心概念(一致性,认知参与,集体行动,自反性监测)的规范化过程理论。组织实施变革准备(ORIC)是基于组织变革准备理论的,衡量组织成员实施变革的心理和行为准备。我们在跨国实施有效性研究中检查了NoMAD和ORIC的测量特性。
    9个国家的12个精神卫生组织对常见的精神障碍实施了基于互联网的认知行为疗法(iCBT)。参与iCBT服务提供的工作人员(n=318)参与了这项研究。这两种方法都使用标准化的前后翻译程序翻译成八种语言。估计了度量和分量表之间的相关性,以检查收敛有效性。使用验证性因子分析(CFA)测试了量表的理论因子结构。重测信度基于相隔3个月的两个时间点的得分之间的相关性。使用Cronbachα评估内部一致性。使用零分数和最大分数的比例来量化地板和天花板效应。
    NoMAD和ORIC测度相关但不同的潜在结构。CFA表明,每个测量使用总分是适当的。NoMAD的理论子量表具有足够的内部一致性。总量表具有较高的内部一致性。总ORIC量表和分量表显示出高度的内部一致性。两种措施的重测可靠性都是次优的,并且没有地板和天花板效应。
    这项研究证实了NoMAD和ORIC在多民族精神卫生保健环境中的心理测量特性。在衡量实施过程的不同但相关的方面时,NoMAD和ORIC被证明在不同的语言设置中是有效和可靠的。
    需要成功实施有效的干预措施才能产生影响。需要可靠的测量仪器来确定实施是否成功。存在两种基于理论的工具来衡量实施战略的有效性和监测进展。NoMAD衡量的是与感官创造相关的标准化方面,执行意愿,人们所做的工作,和反思。组织实施变更的准备程度(ORIC)衡量组织成员实施变更的准备程度。
    这项研究检查了NoMAD和ORIC是否测量了它们应该测量的内容。我们把乐器从英语翻译成八种语言(阿尔巴尼亚语,丹麦语,荷兰人,法语,德语,意大利语,和西班牙语/加泰罗尼亚语)我们应用了各种统计方法来确认测量特性,包括尺度的相关性,因素结构,测试-重测可靠性,一致性和地板和天花板的影响。来自9个国家的318名心理健康专业人员参与了这项研究。
    对于两种仪器,可以使用总分以及子量表得分。ORIC的内部一致性很高,NoMAD足够。证明了重测可靠性,地板和天花板的影响是罕见的。
    NoMAD和ORIC是衡量不同国家和语言的精神卫生保健机构实施过程和结果的可靠工具。它们衡量实施过程和结果的相关但不同的方面。措施很简短,理论支持。然而,在解释与实施成功相关的分数以及随着时间的推移的变化方面,还有更多的工作要做。
    UNASSIGNED: Effective interventions need to be implemented successfully to achieve impact. Two theory-based measures exist for measuring the effectiveness of implementation strategies and monitor implementation progress. The Normalization MeAsure Development questionnaire (NoMAD) explores the four core concepts (Coherence, Cognitive Participation, Collective Action, Reflexive Monitoring) of the Normalization Process Theory. The Organizational Readiness for Implementing Change (ORIC) is based on the theory of Organizational Readiness for Change, measuring organization members\' psychological and behavioral preparedness for implementing a change. We examined the measurement properties of the NoMAD and ORIC in a multi-national implementation effectiveness study.
    UNASSIGNED: Twelve mental health organizations in nine countries implemented Internet-based cognitive behavioral therapy (iCBT) for common mental disorders. Staff involved in iCBT service delivery (n = 318) participated in the study. Both measures were translated into eight languages using a standardized forward-backward translation procedure. Correlations between measures and subscales were estimated to examine convergent validity. The theoretical factor structures of the scales were tested using confirmatory factor analysis (CFA). Test-retest reliability was based on the correlation between scores at two time points 3 months apart. Internal consistency was assessed using Cronbach\'s alpha. Floor and ceiling effects were quantified using the proportion of zero and maximum scores.
    UNASSIGNED: NoMAD and ORIC measure related but distinct latent constructs. The CFA showed that the use of a total score for each measure is appropriate. The theoretical subscales of the NoMAD had adequate internal consistency. The total scale had high internal consistency. The total ORIC scale and subscales demonstrated high internal consistency. Test-retest reliability was suboptimal for both measures and floor and ceiling effects were absent.
    UNASSIGNED: This study confirmed the psychometric properties of the NoMAD and ORIC in multi-national mental health care settings. While measuring on different but related aspects of implementation processes, the NoMAD and ORIC prove to be valid and reliable across different language settings.
    UNASSIGNED: Effective interventions need to be implemented successfully to achieve impact. Reliable measurement instruments are needed to determine if an implementation was successful or not. Two theory-based instruments exist for measuring the effectiveness of implementation strategies and monitor progress. The NoMAD measures aspects of normalization related to sense-making, willingness to implement, the work people do, and reflection. The Organizational Readiness for Implementing Change (ORIC) measures organization members’ preparedness for implementing a change.
    UNASSIGNED: This study examined whether the NoMAD and ORIC measure what they are supposed to measure. We translated the instruments from English to eight languages (Albanian, Danish, Dutch, French, German, Italian, and Spanish/Catalan) We applied various statistical methods to confirm the measurement properties, including correlations of scales, factor structures, test–retest reliability, consistency and floor and ceiling effects. 318 mental health professionals from nine countries participated in the study.
    UNASSIGNED: For both instruments, total scores can be used as well as the subscale scores. Internal consistency for ORIC was high and for NoMAD adequate. Test–retest reliability was demonstrated, and floor and ceiling effects were rare.
    UNASSIGNED: NoMAD and ORIC are reliable instruments for measuring implementation processes and outcomes across mental health care settings in different countries and languages. They measure related but different aspects of implementation processes and outcomes. The measures are brief, and theory supported. However, more work is to be done on interpreting scores in relation to implementation success and regarding changes over time.
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  • 文章类型: Journal Article
    细菌DNA复制的起始发生在复制起点(oriC),特征在于存在充当主起始蛋白DnaA的结合位点的多个DnaA盒的区域。通过在发育或胁迫条件期间调节DnaA和oriC的可用性或活性来严格控制该过程。这里,我们旨在揭示在模型细菌枯草芽孢杆菌中停止复制的生理和分子后果。我们通过采用成簇的间隔短回文重复干扰(CRISPRi)方法特异性靶向关键的DnaA框6和7,成功地阻止了枯草芽孢杆菌的复制,从而阻止了DnaA与oriC的结合。这样,DnaA的其他功能,例如转录调节因子,没有受到重大影响。当复制启动被这种特定的人工和早期阻断停止时,我们观察到非复制细胞持续翻译和细胞生长,并且最初的复制停滞不会引起SOS反应等整体压力条件。重要的是,尽管细菌在实验室条件下不断复制,自然环境使它们面临各种压力,如缺乏营养,高盐度,和pH变化,可以触发非复制状态。这些状态可以使细菌(i)对抗生素(持久性)具有耐受性,(ii)在特定的利基市场中长时间保持不活跃(休眠),(iii)适应恶劣的环境。也已经研究了非复制状态,因为可能重新利用能量来生产额外的代谢物或蛋白质。使用针对细菌复制起始序列的成簇规则间隔的短回文重复干扰(CRISPRi),我们能够成功控制枯草芽孢杆菌的复制起始。这种精确的方法使得研究非复制表型成为可能,有助于更好地理解细菌适应策略。
    Initiation of bacterial DNA replication takes place at the origin of replication (oriC), a region characterized by the presence of multiple DnaA boxes that serve as the binding sites for the master initiator protein DnaA. This process is tightly controlled by modulation of the availability or activity of DnaA and oriC during development or stress conditions. Here, we aimed to uncover the physiological and molecular consequences of stopping replication in the model bacterium Bacillus subtilis. We successfully arrested replication in B. subtilis by employing a clustered regularly interspaced short palindromic repeats interference (CRISPRi) approach to specifically target the key DnaA boxes 6 and 7, preventing DnaA binding to oriC. In this way, other functions of DnaA, such as a transcriptional regulator, were not significantly affected. When replication initiation was halted by this specific artificial and early blockage, we observed that non-replicating cells continued translation and cell growth, and the initial replication arrest did not induce global stress conditions such as the SOS response.IMPORTANCEAlthough bacteria constantly replicate under laboratory conditions, natural environments expose them to various stresses such as lack of nutrients, high salinity, and pH changes, which can trigger non-replicating states. These states can enable bacteria to (i) become tolerant to antibiotics (persisters), (ii) remain inactive in specific niches for an extended period (dormancy), and (iii) adjust to hostile environments. Non-replicating states have also been studied because of the possibility of repurposing energy for the production of additional metabolites or proteins. Using clustered regularly interspaced short palindromic repeats interference (CRISPRi) targeting bacterial replication initiation sequences, we were able to successfully control replication initiation in Bacillus subtilis. This precise approach makes it possible to study non-replicating phenotypes, contributing to a better understanding of bacterial adaptive strategies.
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  • 文章类型: Journal Article
    费氏支原体是一种快速生长的支原体,从野生Caprinae中分离出,并于2013年首次描述。费氏分枝杆菌分离株与关节炎有关,角膜结膜炎,肺炎和败血症,但也从明显健康的动物身上恢复。为了更好地理解这个物种的定义,我们对1987年至2017年间从自由放养或动物园饲养的动物中收集的14株菌株进行了基因组调查,其中大部分在欧洲.费氏分枝杆菌菌株的平均染色体大小为1,040±0,024kbp,24%G+C和852±31CDS。费氏支原体的核心基因组和全基因组包含628和1312个蛋白质家族,分别。费氏分枝杆菌菌株显示出相对封闭的全基因组,具有许多特征和假定的毒力因子,包括MIB-MIPIg裂解系统,DUF285表面蛋白库和半乳聚糖的完整生物合成途径。研究发现费氏分枝杆菌基因组主要是同伦的,虽然流动遗传元件的集合,包括支原体整合和结合元素,插入序列,和单个质粒变化。系统发育和基因含量分析证实,与反刍动物物种M.yeatsii和putrefaciens相比,费氏M.mycoides簇更接近。祖先基因组重建表明,费氏支原体物种的出现与17个基因家族的获得有关,其中一些编码防御酶和表面蛋白,以及另外25人的损失,其中一些参与糖的运输和代谢。这项比较研究表明,可以将M.mycoides簇扩展到包括费氏支原体。我们还发现了证据,表明费氏支原体oriC周围DnaA盒的特定组织和结构可能有助于驱动这种最小细菌的显着快速生长。
    Mycoplasma feriruminatoris is a fast-growing Mycoplasma species isolated from wild Caprinae and first described in 2013. M. feriruminatoris isolates have been associated with arthritis, kerato conjunctivitis, pneumonia and septicemia, but were also recovered from apparently healthy animals. To better understand what defines this species, we performed a genomic survey on 14 strains collected from free-ranging or zoo-housed animals between 1987 and 2017, mostly in Europe. The average chromosome size of the M. feriruminatoris strains was 1,040±0,024 kbp, with 24 % G+C and 852±31 CDS. The core genome and pan-genome of the M. feriruminatoris species contained 628 and 1312 protein families, respectively. The M. feriruminatoris strains displayed a relatively closed pan-genome, with many features and putative virulence factors shared with species from the M. mycoides cluster, including the MIB-MIP Ig cleavage system, a repertoire of DUF285 surface proteins and a complete biosynthetic pathway for galactan. M. feriruminatoris genomes were found to be mostly syntenic, although repertoires of mobile genetic elements, including Mycoplasma Integrative and Conjugative Elements, insertion sequences, and a single plasmid varied. Phylogenetic- and gene content analyses confirmed that M. feriruminatoris was closer to the M. mycoides cluster than to the ruminant species M. yeatsii and M. putrefaciens. Ancestral genome reconstruction showed that the emergence of the M. feriruminatoris species was associated with the gain of 17 gene families, some of which encode defence enzymes and surface proteins, and the loss of 25 others, some of which are involved in sugar transport and metabolism. This comparative study suggests that the M. mycoides cluster could be extended to include M. feriruminatoris. We also find evidence that the specific organization and structure of the DnaA boxes around the oriC of M. feriruminatoris may contribute to drive the remarkable fast growth of this minimal bacterium.
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  • 文章类型: Journal Article
    长期以来,人们一直认为DnaA蛋白在现代细菌染色体复制的启动中起关键作用。关于这个角色的很多问题,然而,仍然没有答案。这里,我们在基于超结构动力学的框架内提出这些问题,别名执行功能的分子和大分子的大型组装。在这些动态中,超结构可以(1)发射和接收信号或(2)相互融合和分离。我们询问基于DnaA的起始超结构是否充当从膜接收信息的逻辑门,染色体,和新陈代谢来触发复制;我们试图用DNA超螺旋来表达这些问题中的一些,钢绞线开口,糖酵解酶,SeqA,核糖核苷酸还原酶,大分子合成操纵子,翻译后修饰,和代谢池。最后,我们问是否,支持细胞周期的调节,第一个原始细胞遗传了一个物理化学时钟,以及这个时钟是否发出触发染色体复制和细胞分裂的单一信号。
    The DnaA protein has long been considered to play the key role in the initiation of chromosome replication in modern bacteria. Many questions about this role, however, remain unanswered. Here, we raise these questions within a framework based on the dynamics of hyperstructures, alias large assemblies of molecules and macromolecules that perform a function. In these dynamics, hyperstructures can (1) emit and receive signals or (2) fuse and separate from one another. We ask whether the DnaA-based initiation hyperstructure acts as a logic gate receiving information from the membrane, the chromosome, and metabolism to trigger replication; we try to phrase some of these questions in terms of DNA supercoiling, strand opening, glycolytic enzymes, SeqA, ribonucleotide reductase, the macromolecular synthesis operon, post-translational modifications, and metabolic pools. Finally, we ask whether, underpinning the regulation of the cell cycle, there is a physico-chemical clock inherited from the first protocells, and whether this clock emits a single signal that triggers both chromosome replication and cell division.
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  • 文章类型: Journal Article
    这篇综述总结了当前有关两核蛋白及时结合和解离机制的知识,IHF和Fis,在大肠杆菌中染色体DNA复制的启动中起着基本作用。复制从称为oriC的独特复制起点开始,并受到严格调控,因此每个细胞周期仅发生一次。oriC处复制起始的时间由起始蛋白DnaA和IHF与oriC的及时结合严格控制。本综述的第一部分介绍了有关在复制启动过程中oriC-IHF结合及时稳定的最新知识。我们对细胞周期协调的IHF结合的全基因组谱的理解的最新进展揭示了通过oriC处的ATP-DnaA寡聚体和通过oriC处的起始特异性IHF结合共有序列对IHF结合的oriC特异性稳定。本综述的第二部分总结了通过染色体基因座DARS2(DnaA再激活序列2)和datA及时调节DnaA活性的机制。oriC的复制起始时间主要受与DnaA结合的腺苷核苷酸的磷酸化形式控制,即,ATP-DnaA,但不是ADP-ADP,有能力启动。入会前,DARS2通过刺激DnaA上的ADP与ATP的交换来增加ATP-DnaA的水平。该DARS2功能通过DARS2内IHF和Fis两者的位点特异性和及时结合而激活。入会后,另一个染色体位点,datA,通过刺激ATP水解使ATP-DnaA失活,被IHF的及时结合激活。最近的一项研究表明,在DARS2-Fis结合位点形成的ATP-DnaA寡聚体通过负反馈竞争性解离Fis,而IHF在DARS2和datA的调控仍有待研究。这篇综述总结了有关IHF和Fis在复制起始调节中的特定作用的最新知识,并提出了在DARS2和datA上及时IHF结合和解离的调节机制。
    This review summarizes current knowledge about the mechanisms of timely binding and dissociation of two nucleoid proteins, IHF and Fis, which play fundamental roles in the initiation of chromosomal DNA replication in Escherichia coli. Replication is initiated from a unique replication origin called oriC and is tightly regulated so that it occurs only once per cell cycle. The timing of replication initiation at oriC is rigidly controlled by the timely binding of the initiator protein DnaA and IHF to oriC. The first part of this review presents up-to-date knowledge about the timely stabilization of oriC-IHF binding at oriC during replication initiation. Recent advances in our understanding of the genome-wide profile of cell cycle-coordinated IHF binding have revealed the oriC-specific stabilization of IHF binding by ATP-DnaA oligomers at oriC and by an initiation-specific IHF binding consensus sequence at oriC. The second part of this review summarizes the mechanism of the timely regulation of DnaA activity via the chromosomal loci DARS2 (DnaA-reactivating sequence 2) and datA. The timing of replication initiation at oriC is controlled predominantly by the phosphorylated form of the adenosine nucleotide bound to DnaA, i.e., ATP-DnaA, but not ADP-ADP, is competent for initiation. Before initiation, DARS2 increases the level of ATP-DnaA by stimulating the exchange of ADP for ATP on DnaA. This DARS2 function is activated by the site-specific and timely binding of both IHF and Fis within DARS2. After initiation, another chromosomal locus, datA, which inactivates ATP-DnaA by stimulating ATP hydrolysis, is activated by the timely binding of IHF. A recent study has shown that ATP-DnaA oligomers formed at DARS2-Fis binding sites competitively dissociate Fis via negative feedback, whereas IHF regulation at DARS2 and datA still remains to be investigated. This review summarizes the current knowledge about the specific role of IHF and Fis in the regulation of replication initiation and proposes a mechanism for the regulation of timely IHF binding and dissociation at DARS2 and datA.
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  • 文章类型: Clinical Trial Protocol
    背景:低收入和中等收入国家(LMICs)一项重要的宫颈癌预防策略是单次就诊筛查和治疗(SV-SAT)方法,使用乙酸(VIA)的目视检查和冷冻疗法的消融治疗来管理癌前病变。虽然SV-SAT与VIA和冷冻疗法已经确立了疗效,其人口水平的覆盖率和对降低宫颈癌负担的影响仍然很低。在肯尼亚,30-49岁女性的宫颈癌筛查率估计为16%,高达70%的筛查阳性女性未接受治疗.世界卫生组织建议进行热消融治疗宫颈癌前病变,并有可能克服与冷冻治疗相关的后勤挑战,并促进SV-SAT方法的实施并提高筛查阳性妇女的治疗率。在这个五年的前景中,阶梯式楔形随机试验,我们计划在肯尼亚中部的10个生殖健康诊所实施和评估使用VIA和热消融的SV-SAT方法.
    方法:该研究旨在制定和评估实施策略,以通过以下三个目标为国家推广使用VIA和热消融的SV-SAT方法提供信息:(1)与关键利益相关者(患者,提供者,系统级),(2)通过VIA和热消融实施SV-SAT方法,并评估临床和实施结果,和(3)评估与单次访问相比,使用VIA和热消融的SV-SAT方法的预算影响,使用冷冻疗法的筛查和治疗方法。
    结论:我们的研究结果将为全国范围内采用VIA和热消融的SV-SAT方法的推广提供参考。我们预计这次干预,与使用冷冻疗法的护理标准相比,量身定制的实施策略将增强宫颈癌筛查和治疗的采用和可持续性。
    背景:NCT05472311。
    An important cervical cancer prevention strategy in low- and middle-income countries (LMICs) has been single-visit screen-and-treat (SV-SAT) approach, using visual inspection with acetic acid (VIA) and ablative treatment with cryotherapy to manage precancerous lesions. While SV-SAT with VIA and cryotherapy have established efficacy, its population level coverage and impact on reducing cervical cancer burden remains low. In Kenya, the estimated cervical cancer screening uptake among women aged 30-49 is 16% and up to 70% of screen-positive women do not receive treatment. Thermal ablation for treatment of precancerous lesions of the cervix is recommended by the World Health Organization and has the potential to overcome logistical challenges associated with cryotherapy and facilitate implementation of SV-SAT approach and increase treatment rates of screen-positive women. In this 5-year prospective, stepped-wedge randomized trial, we plan to implement and evaluate the SV-SAT approach using VIA and thermal ablation in ten reproductive health clinics in central Kenya.
    The study aims to develop and evaluate implementation strategies to inform the national scale-up of SV-SAT approach with VIA and thermal ablation through three aims: (1) develop locally tailored implementation strategies using multi-level participatory method with key stakeholders (patient, provider, system-level), (2) implement SV-SAT approach with VIA and thermal ablation and evaluate clinical and implementation outcomes, and (3) assess the budget impact of SV-SAT approach with VIA and thermal ablation compared to single-visit, screen-and-treat method using cryotherapy.
    Our findings will inform national scale-up of the SV-SAT approach with VIA and thermal ablation. We anticipate that this intervention, along with tailored implementation strategies will enhance the adoption and sustainability of cervical cancer screening and treatment compared to the standard of care using cryotherapy.
    NCT05472311.
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  • 文章类型: Journal Article
    染色体复制的启动需要动态核蛋白复合物。在大多数真细菌中,oriC包含多个DnaA盒序列,与普遍存在的DnaA引发剂结合。在大肠杆菌oriC中,DnaA盒通过DnaA-DnaA相互作用维持高阶复合物的构建,促进oriC内DNA解绕元件(DUE)的解绕,并同时结合单链DUE以安装复制机器。尽管DnaA蛋白之间存在显著的序列同源性,细菌oriC序列是高度多样化的。本研究调查了来自Thermotogamaritima的oriC(tma-oriC)的设计,进化上古老的真细菌。最小tma-oriC序列包括DUE和含有由同源DnaA起始物(tmaDnaA)识别的五个DnaA盒的侧翼区。该DUE由两个不同的功能模块组成,展开模块和tmaDnaA绑定模块。DUE内三核苷酸TAG的三个直接重复对于在DnaA盒上构建的tmaDnaA复合物的解链和单链DUE结合都是必不可少的。其周围富含AT的序列仅刺激双链体展开。此外,在tma-oriC内构建ATP结合的tmaDnaA的头尾寡聚体,不管DnaA盒子的方向。这种结合模式被认为是由DnaA结构域III和IV的柔性旋转诱导的。它们负责DnaA-DnaA相互作用和DnaA盒结合,分别。tma-oriCDNA中特定tmaDnaA盒的定相也负责解链。这些发现表明,单股DUE招募机制负责解套,并且将增强对进化差异细菌中存在的起源序列的基本分子性质的理解。
    Initiation of chromosomal replication requires dynamic nucleoprotein complexes. In most eubacteria, the origin oriC contains multiple DnaA box sequences to which the ubiquitous DnaA initiators bind. In Escherichia coli oriC, DnaA boxes sustain construction of higher-order complexes via DnaA-DnaA interactions, promoting the unwinding of the DNA unwinding element (DUE) within oriC and concomitantly binding the single-stranded (ss) DUE to install replication machinery. Despite the significant sequence homologies among DnaA proteins, oriC sequences are highly diverse. The present study investigated the design of oriC (tma-oriC) from Thermotoga maritima, an evolutionarily ancient eubacterium. The minimal tma-oriC sequence includes a DUE and a flanking region containing five DnaA boxes recognized by the cognate DnaA (tmaDnaA). This DUE was comprised of two distinct functional modules, an unwinding module and a tmaDnaA-binding module. Three direct repeats of the trinucleotide TAG within DUE were essential for both unwinding and ssDUE binding by tmaDnaA complexes constructed on the DnaA boxes. Its surrounding AT-rich sequences stimulated only duplex unwinding. Moreover, head-to-tail oligomers of ATP-bound tmaDnaA were constructed within tma-oriC, irrespective of the directions of the DnaA boxes. This binding mode was considered to be induced by flexible swiveling of DnaA domains III and IV, which were responsible for DnaA-DnaA interactions and DnaA box binding, respectively. Phasing of specific tmaDnaA boxes in tma-oriC was also responsible for unwinding. These findings indicate that a ssDUE recruitment mechanism was responsible for unwinding and would enhance understanding of the fundamental molecular nature of the origin sequences present in evolutionarily divergent bacteria.
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  • 文章类型: Journal Article
    大约五十年前,使用重组DNA技术构建大肠杆菌微小染色体成为可能。这些非常小的复制子,包含与耐药标记偶联的染色体oriC的独特复制起点,为研究细菌染色体复制的调控提供了新的机会,是获得编码到oriC中的核苷酸序列信息的关键,并且对于开发突破性的体外复制系统至关重要。然而,微小染色体模型系统的真正真实性要求它们在细胞周期中以染色体样的定时特异性进行复制。我很幸运地有机会在CharlesHelmstetter的实验室中构建大肠杆菌微小染色体,第一次,测量微小染色体细胞周期调节。在这次审查中,我讨论了该项目的发展以及从那时起与DNA拓扑和微小染色体的分离特性有关的一些其他研究。尽管时间流逝,很明显,我们对oriC监管的理解仍然存在很大差距。我讨论了一些继续值得进一步研究的具体主题。
    Nearly fifty years ago, it became possible to construct E. coli minichromosomes using recombinant DNA technology. These very small replicons, comprising the unique replication origin of the chromosome oriC coupled to a drug resistance marker, provided new opportunities to study the regulation of bacterial chromosome replication, were key to obtaining the nucleotide sequence information encoded into oriC and were essential for the development of a ground-breaking in vitro replication system. However, true authenticity of the minichromosome model system required that they replicate during the cell cycle with chromosome-like timing specificity. I was fortunate enough to have the opportunity to construct E. coli minichromosomes in the laboratory of Charles Helmstetter and, for the first time, measure minichromosome cell cycle regulation. In this review, I discuss the evolution of this project along with some additional studies from that time related to the DNA topology and segregation properties of minichromosomes. Despite the significant passage of time, it is clear that large gaps in our understanding of oriC regulation still remain. I discuss some specific topics that continue to be worthy of further study.
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  • 文章类型: Journal Article
    遗传信息的复制和分离是细胞增殖所必需的。在枯草芽孢杆菌中,标准杆系统(ParA/Soj,ParB/Spo0J和parS)是染色体起源(oriC)区域的分离和DNA复制起始的适当控制所必需的。ParB结合聚集在复制起点附近的parS位点,并组装成与ParA相互作用的滑动夹具,以通过扩散棘轮机制驱动起点分离。作为这个动态过程的一部分,ParB刺激ParAATP酶活性以触发其从ATP结合的二聚体转换为ADP结合的单体。除了它在DNA分离中的保守作用,ParA也是主DNA复制起始蛋白DnaA的调节剂。我们假设在枯草芽孢杆菌中,Par系统在oriC附近的位置对于ParA正确调节DnaA是必需的。为了测试这个模型,我们构建了一系列具有改变数量和位置的parS位点的转基因菌株,其中许多干扰了预期的染色体起源分离。与我们的假设相反,结果表明,当parS位点与oriC分离时,ParA对DNA复制起始的调节得以维持。因为单个parS站点足以适当控制ParA,结果与ParA在ParS加载后由ParB滑动夹具有效调节的模型一致。
    Replication and segregation of the genetic information is necessary for a cell to proliferate. In Bacillus subtilis, the Par system (ParA/Soj, ParB/Spo0J and parS) is required for segregation of the chromosome origin (oriC) region and for proper control of DNA replication initiation. ParB binds parS sites clustered near the origin of replication and assembles into sliding clamps that interact with ParA to drive origin segregation through a diffusion-ratchet mechanism. As part of this dynamic process, ParB stimulates ParA ATPase activity to trigger its switch from an ATP-bound dimer to an ADP-bound monomer. In addition to its conserved role in DNA segregation, ParA is also a regulator of the master DNA replication initiation protein DnaA. We hypothesized that in B. subtilis the location of the Par system proximal to oriC would be necessary for ParA to properly regulate DnaA. To test this model, we constructed a range of genetically modified strains with altered numbers and locations of parS sites, many of which perturbed chromosome origin segregation as expected. Contrary to our hypothesis, the results show that regulation of DNA replication initiation by ParA is maintained when a parS site is separated from oriC. Because a single parS site is sufficient for proper control of ParA, the results are consistent with a model where ParA is efficiently regulated by ParB sliding clamps following loading at parS.
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  • 文章类型: Journal Article
    链霉菌是居住在土壤中的多细胞微生物,以其前所未有的合成多种生物活性天然产物(NP)的能力而闻名。除了丰富的次级代谢产物,链霉菌的特征在于复杂的形态分化。大多数情况下,NPs的工业生产是通过深层发酵完成的,其中链霉菌生长为形成颗粒的营养菌丝体。通常,次优增长特性是工业开发的主要瓶颈。在这项工作中,我们采用基因工程方法来提高加纳链霉菌中莫恩霉素(Mm)的产量,唯一已知的细菌肽聚糖糖基转移的天然直接抑制剂。我们表明,在体内消除oriC区域中多效调节剂AdpA的结合位点会强烈影响生长,并与Mm积累呈正相关。此外,moeH5的标记和“疤痕”少缺失,编码来自Mm基因簇的酰胺基转移酶,大大缩小了毫米生产范围。引人注目的是,通过消除多效性调节基因wblA,抗生素滴度得到了强烈增强,参与形态发生的后期步骤。总之,我们用优化的生长参数生成了Mm过量生产者,其可用于进一步的基因组工程和新型Mm衍生物的化学酶促生成。类似地,这样的方案可以应用于其他链霉菌属。
    Streptomycetes are soil-dwelling multicellular microorganisms famous for their unprecedented ability to synthesize numerous bioactive natural products (NPs). In addition to their rich arsenal of secondary metabolites, Streptomyces are characterized by complex morphological differentiation. Mostly, industrial production of NPs is done by submerged fermentation, where streptomycetes grow as a vegetative mycelium forming pellets. Often, suboptimal growth peculiarities are the major bottleneck for industrial exploitation. In this work, we employed genetic engineering approaches to improve the production of moenomycins (Mm) in Streptomyces ghanaensis, the only known natural direct inhibitors of bacterial peptidoglycan glycosyltransferses. We showed that in vivo elimination of binding sites for the pleiotropic regulator AdpA in the oriC region strongly influences growth and positively correlates with Mm accumulation. Additionally, a marker- and \"scar\"-less deletion of moeH5, encoding an amidotransferase from the Mm gene cluster, significantly narrows down the Mm production spectrum. Strikingly, antibiotic titers were strongly enhanced by the elimination of the pleiotropic regulatory gene wblA, involved in the late steps of morphogenesis. Altogether, we generated Mm overproducers with optimized growth parameters, which are useful for further genome engineering and chemoenzymatic generation of novel Mm derivatives. Analogously, such a scheme can be applied to other Streptomyces spp.
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