scholarly journals Type II Secretion-Dependent Aminopeptidase LapA and Acyltransferase PlaC Are Redundant for Nutrient Acquisition duringLegionella pneumophilaIntracellular Infection of Amoebas

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. e00528-18 ◽  
Author(s):  
Richard C. White ◽  
Felizza F. Gunderson ◽  
Jessica Y. Tyson ◽  
Katherine H. Richardson ◽  
Theo J. Portlock ◽  
...  
Keyword(s):  
Amino Acids ◽  
Substrate Specificity ◽  
Transcriptional Analysis ◽  
Type Ii Secretion ◽  
Major Advance ◽  
Type Ii ◽  
Content Type ◽  
Broad Substrate Specificity ◽  
First Time

ABSTRACTLegionella pneumophilagenes encoding LapA, LapB, and PlaC were identified as the most highly upregulated type II secretion (T2S) genes during infection ofAcanthamoeba castellanii, although these genes had been considered dispensable on the basis of the behavior of mutants lacking eitherlapAandlapBorplaC. AplaCmutant showed even higher levels oflapAandlapBtranscripts, and alapA lapBmutant showed heightening ofplaCmRNA levels, suggesting that the role of the LapA/B aminopeptidase is compensatory with respect to that of the PlaC acyltransferase. Hence, we made double mutants and found thatlapA plaCmutants have an ~50-fold defect during infection ofA. castellanii. These data revealed, for the first time, the importance of LapA in any sort of infection; thus, we purified LapA and defined its crystal structure, activation by another T2S-dependent protease (ProA), and broad substrate specificity. When the amoebal infection medium was supplemented with amino acids, the defect of thelapA plaCmutant was reversed, implying that LapA generates amino acids for nutrition. Since the LapA and PlaC data did not fully explain the role of T2S in infection, we identified, via proteomic analysis, a novel secreted protein (NttD) that promotes infection ofA. castellanii. AlapA plaC nttDmutant displayed an even greater (100-fold) defect, demonstrating that the LapA, PlaC, and NttD data explain, to a significant degree, the importance of T2S. LapA-, PlaC-, and NttD-like proteins had distinct distribution patterns within and outside theLegionellagenus. LapA was notable for having as its closest homologue anA. castellaniiprotein.IMPORTANCETransmission ofL. pneumophilato humans is facilitated by its ability to grow inAcanthamoebaspecies. We previously documented that type II secretion (T2S) promotesL. pneumophilainfection ofA. castellanii. Utilizing transcriptional analysis and proteomics, double and triple mutants, and crystal structures, we defined three secreted substrates/effectors that largely clarify the role of T2S during infection ofA. castellanii. Particularly interesting are the unique functional overlap between an acyltransferase (PlaC) and aminopeptidase (LapA), the broad substrate specificity and eukaryotic-protein-like character of LapA, and the novelty of NttD. Linking LapA to amino acid acquisition, we defined, for the first time, the importance of secreted aminopeptidases in intracellular infection. Bioinformatic investigation, not previously applied to T2S, revealed that effectors originate from diverse sources and distribute within theLegionellagenus in unique ways. The results of this study represent a major advance in understandingLegionellaecology and pathogenesis, bacterial secretion, and the evolution of intracellular parasitism.

scholarly journals Photobacterium damselae subsp. damselae Major Virulence Factors Dly, Plasmid-Encoded HlyA, and Chromosome-Encoded HlyA Are Secreted via the Type II Secretion System

2015 ◽  
Vol 83 (4) ◽  
pp. 1246-1256 ◽  
Author(s):  
Amable J. Rivas ◽  
Ana Vences ◽  
Matthias Husmann ◽  
Manuel L. Lemos ◽  
Carlos R. Osorio
Keyword(s):  
Secretion System ◽  
Transcriptional Level ◽  
Type Ii Secretion ◽  
Type Ii ◽  
Marine Animals ◽  
Content Type ◽  
Type Ii Secretion System ◽  
Photobacterium Damselae ◽  
Prepilin Peptidase

Photobacterium damselaesubsp.damselaeis a marine bacterium that causes septicemia in marine animals and in humans. Previously, we had determined a major role of pPHDD1 plasmid-encoded Dly (damselysin) and HlyA (HlyApl) and the chromosome-encoded HlyA (HlyAch) hemolysins in virulence. However, the mechanisms by which these toxins are secreted remain unknown. In this study, we found that a mini-Tn10transposon mutant in a plasmidless strain showing an impaired hemolytic phenotype contained an insertion inepsL, a component of a type II secretion system (T2SS). Reconstruction of the mutant by allelic exchange confirmed the specific involvement ofepsLin HlyAchsecretion. In addition, mutation ofepsLin a pPHDD1-harboring strain caused an almost complete abolition of hemolytic activity against sheep erythrocytes, indicating thatepsLplays a major role in secretion of the plasmid-encoded HlyApland Dly. This was further demonstrated by analysis of different combinations of hemolysin gene mutants and by strain-strain complementation assays. We also found that mutation of the putative prepilin peptidase genepilDseverely affected hemolysis, which dropped at levels inferior to those ofepsLmutants. Promoter expression analyses suggested that impairment of hemolysin secretion inepsLandpilDmutants might constitute a signal that affects hemolysin and T2SS gene expression at the transcriptional level. In addition, singleepsLandpilDmutations caused a drastic decrease in virulence for mice, demonstrating a major role of T2SS andpilDinP. damselaesubsp.damselaevirulence.

A “Learning from Action” workshop in Japan

2019 ◽  
Vol 40 (2) ◽  
pp. 77-83
Author(s):  
Robert Douglas Hinshelwood ◽  
Luca Mingarelli ◽  
Simona Masnata
Keyword(s):  
Far East ◽  
Opportunity To Learn ◽  
Content Type ◽  
Work Activities ◽  
Defensive Role ◽  
Feedback Data ◽  
Experiential Workshop ◽  
First Time ◽  
Practical Implications

Purpose Many people in severe mentally disturbed states do not use language or other symbolic media well or coherently. Therefore, the non-verbal medium needs to be understood by workers with such people. The “Learning from Action” experiential workshop was developed in order to provide an opportunity to learn about hidden messages in the relationships and roles occurring in activities. In August 2017, a workshop was run for the first time in Japan. The purpose of this paper is to report the experience and dynamics observed by the three consultants, who are here the authors of this paper. Design/methodology/approach After the workshop all the staff and members, including interpreters, were invited to give feedback. Findings Analysis of the feedback data showed certain important dynamics, concerning especially dependence, cultural defences and the defensive role of activity in a multicultural context. Research limitations/implications This is an initial experience to be followed up by later feedback and further workshops. Practical implications Workers awareness of non-verbal communication within the roles of work activities is a training possibility. It faces various resistances including the mental health assumptions of meaninglessness of any communication outside the verbal. Originality/value This is a method of training not widely used even in European countries, and is the first in a country in the far east.

Seeking attention: an eye tracking study of in-store merchandise displays

2015 ◽  
Vol 43 (6) ◽  
pp. 561-574 ◽  
Author(s):  
Patricia Huddleston ◽  
Bridget K. Behe ◽  
Stella Minahan ◽  
R. Thomas Fernandez
Keyword(s):  
Visual Attention ◽  
Eye Tracking ◽  
Purchase Intention ◽  
Product Information ◽  
Product Category ◽  
Practical Significance ◽  
Content Type ◽  
First Time ◽  
Tracking Technology

Purpose – The purpose of this paper is to elucidate the role that visual measures of attention to product and information and price display signage have on purchase intention. The authors assessed the effect of visual attention to the product, information or price sign on purchase intention, as measured by likelihood to buy. Design/methodology/approach – The authors used eye-tracking technology to collect data from Australian and US garden centre customers, who viewed eight plant displays in which the signs had been altered to show either price or supplemental information (16 images total). The authors compared the role of visual attention to price and information sign, and the role of visual attention to the product when either sign was present on likelihood to buy. Findings – Overall, providing product information on a sign without price elicited higher likelihood to buy than providing a sign with price. The authors found a positive relationship between visual attention to price on the display sign and likelihood to buy, but an inverse relationship between visual attention to information and likelihood to buy. Research limitations/implications – An understanding of the attention-capturing power of merchandise display elements, especially signs, has practical significance. The findings will assist retailers in creating more effective and efficient display signage content, for example, featuring the product information more prominently than the price. The study was conducted on a minimally packaged product, live plants, which may reduce the ability to generalize findings to other product types. Practical implications – The findings will assist retailers in creating more effective and efficient display signage content. The study used only one product category (plants) which may reduce the ability to generalize findings to other product types. Originality/value – The study is one of the first to use eye-tracking in a macro-level, holistic investigation of the attention-capturing value of display signage information and its relationship to likelihood to buy. Researchers, for the first time, now have the ability to empirically test the degree to which attention and decision-making are linked.

Introducing multivariate Markov modeling within QFD to anticipate future customer preferences in product design

2018 ◽  
Vol 35 (3) ◽  
pp. 762-778 ◽  
Author(s):  
Katerina Gotzamani ◽  
Andreas Georgiou ◽  
Andreas Andronikidis ◽  
Konstantina Kamvysi
Keyword(s):  
Quality Function Deployment ◽  
Fuzzy Ahp ◽  
Markov Modeling ◽  
Design Decisions ◽  
Content Type ◽  
Customer Preferences ◽  
First Time ◽  
The Voice ◽  
Product Specifications

Purpose The purpose of this paper is to provide an enhanced version of quality function deployment (QFD) that captures customers’ present and future preferences, accurately prioritizes product specifications and eventually translates them into desirable quality products. Under rapidly changing environments, customer requirements and preferences are constantly changing and evolving, rendering essential the realization of the dynamic role of the “Voice of the Customer (VoC)” in the design and development of products. Design/methodology/approach The proposed methodological framework incorporates a Multivariate Markov Chain (MMC) model to describe the pattern of changes in customer preferences over time, the Fuzzy AHP method to accommodate the uncertainty and subjectivity of the “VoC” and the LP-GW-AHP to discover the most important product specifications in order to structure a robust QFD method. This enhanced QFD framework (MMC-QFD-LP-GW-Fuzzy AHP) takes into consideration the dynamic nature of the “VoC” captures the actual customers’ preferences (WHATs) and interprets them into design decisions (HOWs). Findings The integration of MMC models into the QFD helps to handle the sequences of customers’ preferences as categorical data sequences and to consider the multiple interdependencies among them. Originality/value In this study, a MMC model is introduced for the first time within QFD, in an effort to extend the concept of listening to further anticipating to customer wants. Gaining a deeper understanding of current and future customers’ preferences could help organizations to design products and plan strategies that more effectively and efficiently satisfy them.

Reflections from the field (mountain, cityscape and park): walking for management development and links to being-in-the world, belonging and “Ba”

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Arthur F. Turner ◽  
Gareth Edwards ◽  
Catherine Latham ◽  
Harriet Shortt
Keyword(s):  
Leadership Development ◽  
Management Development ◽  
Learning And Development ◽  
Content Type ◽  
Personal Story ◽  
The World ◽  
Effective Use ◽  
The Impact ◽  
First Time

PurposeThe purpose of this paper, based on reflections from practice, is to shed light on the realities of using walking as a tool for learning and development. This is done through an initial analysis of longitudinal reflective data spanning seven years and connecting these reflections to the concepts: being-in-the-world, belonging and Ba.Design/methodology/approachThis research takes a practice based phenomenological and reflective approach. The value of this approach is to seek a new understanding, through three distinct conceptual frames, of the effective use of walking within management development.FindingsThe findings connect three conceptual approaches of being-in-the-world, belonging and “Ba” to the practicalities of delivery, thus encouraging practitioners and designers to deeply reflect on the role of walking in management development.Research limitations/implicationsA limitation is that this is largely a personal story exploring the impact of an intuitively developed set of interventions. Despite this, the paper represents a unique and deep interpretation of walking as a mechanism for management development.Practical implicationsThe paper concludes with three recommendations to practitioners wanting to use walking in management development programmes. These are: facilitators need to be familiar with their surroundings; they should look for spaces and places where participants can connect and build relationships; and organisers and sponsors need to recognise how walking not only consolidates knowledge but can help create knowledge too.Originality/valueThis is a unique, seven-year longitudinal study that broadens the theoretical focus of walking as a mechanism for management and leadership development that combines the theoretical lenses of being-in-the-world, belonging and “Ba”, the authors believe, for the first time in research on management development.

scholarly journals Molecular Basis of Substrate Recognition of Endonuclease Q from the Euryarchaeon Pyrococcus furiosus

2019 ◽  
Vol 202 (2) ◽  
Author(s):  
Miyako Shiraishi ◽  
Shigenori Iwai
Keyword(s):  
Dna Repair ◽  
Bacillus Subtilis ◽  
Substrate Specificity ◽  
Molecular Basis ◽  
Pyrococcus Furiosus ◽  
Substrate Recognition ◽  
Base Flipping ◽  
Content Type ◽  
Cleavage Activity

ABSTRACT Endonuclease Q (EndoQ), a DNA repair endonuclease, was originally identified in the hyperthermophilic euryarchaeon Pyrococcus furiosus in 2015. EndoQ initiates DNA repair by generating a nick on DNA strands containing deaminated bases and an abasic site. Although EndoQ is thought to be important for maintaining genome integrity in certain bacteria and archaea, the underlying mechanism catalyzed by EndoQ remains unclear. Here, we provide insights into the molecular basis of substrate recognition by EndoQ from P. furiosus (PfuEndoQ) using biochemical approaches. Our results of the substrate specificity range and the kinetic properties of PfuEndoQ demonstrate that PfuEndoQ prefers the imide structure in nucleobases along with the discovery of its cleavage activity toward 5,6-dihydrouracil, 5-hydroxyuracil, 5-hydroxycytosine, and uridine in DNA. The combined results for EndoQ substrate binding and cleavage activity analyses indicated that PfuEndoQ flips the target base from the DNA duplex, and the cleavage activity is highly dependent on spontaneous base flipping of the target base. Furthermore, we find that PfuEndoQ has a relatively relaxed substrate specificity; therefore, the role of EndoQ in restriction modification systems was explored. The activity of the EndoQ homolog from Bacillus subtilis was found not to be inhibited by the uracil glycosylase inhibitor from B. subtilis bacteriophage PBS1, whose genome is completely replaced by uracil instead of thymine. Our findings suggest that EndoQ not only has additional functions in DNA repair but also could act as an antiviral enzyme in organisms with EndoQ. IMPORTANCE Endonuclease Q (EndoQ) is a lesion-specific DNA repair enzyme present in certain bacteria and archaea. To date, it remains unclear how EndoQ recognizes damaged bases. Understanding the mechanism of substrate recognition by EndoQ is important to grasp genome maintenance systems in organisms with EndoQ. Here, we find that EndoQ from the euryarchaeon Pyrococcus furiosus recognizes the imide structure in nucleobases by base flipping, and the cleavage activity is enhanced by the base pair instability of the target base, along with the discovery of its cleavage activity toward 5,6-dihydrouracil, 5-hydroxyuracil, 5-hydroxycytosine, and uridine in DNA. Furthermore, a potential role of EndoQ in Bacillus subtilis as an antiviral enzyme by digesting viral genome is demonstrated.

Too resilient for anyone’s good

Kybernetes ◽  
2019 ◽  
Vol 48 (4) ◽  
pp. 751-768 ◽  
Author(s):  
Lance Nizami
Keyword(s):  
Auditory Stimulus ◽  
Design Methodology ◽  
Detection Thresholds ◽  
Content Type ◽  
Infant Vision ◽  
Efficacious Treatment ◽  
Stimulus Detection ◽  
First Time

Purpose This study aims to examine the observer’s role in “infant psychophysics”. Infant psychophysics was developed because the diagnosis of perceptual deficits should be done as early in a patient’s life as possible, to provide efficacious treatment and thereby reduce potential long-term costs. Infants, however, cannot report their perceptions. Hence, the intensity of a stimulus at which the infant can detect it, the “threshold”, must be inferred from the infant’s behavior, as judged by observers (watchers). But whose abilities are actually being inferred? The answer affects all behavior-based conclusions about infants’ perceptions, including the well-proselytized notion that auditory stimulus-detection thresholds improve rapidly during infancy. Design/methodology/approach In total, 55 years of infant psychophysics is scrutinized, starting with seminal studies in infant vision, followed by the studies that they inspired in infant hearing. Findings The inferred stimulus-detection thresholds are those of the infant-plus-watcher and, more broadly, the entire laboratory. The thresholds are therefore tenuous, because infants’ actions may differ with stimulus intensity; expressiveness may differ between infants; different watchers may judge infants differently; etc. Particularly, the watcher’s ability to “read” the infant may improve with the infant’s age, confounding any interpretation of perceptual maturation. Further, the infant’s gaze duration, an assumed cue to stimulus detection, may lengthen or shorten nonlinearly with infant age. Research limitations/implications Infant psychophysics investigators have neglected the role of the observer, resulting in an accumulation of data that requires substantial re-interpretation. Altogether, infant psychophysics has proven far too resilient for its own good. Originality/value Infant psychophysics is examined for the first time through second-order cybernetics. The approach reveals serious unresolved issues.

Insurance regulations, risk and performance in Ghana

2019 ◽  
Vol 28 (1) ◽  
pp. 74-96
Author(s):  
Baah Aye Kusi ◽  
Abdul Latif Alhassan ◽  
Daniel Ofori-Sasu ◽  
Rockson Sai
Keyword(s):  
Random Effect ◽  
Least Square ◽  
Insurance Market ◽  
Content Type ◽  
Ordinary Least Square ◽  
Negative Effect ◽  
And Performance ◽  
First Time

Purpose This study aims to examine the hypothesis that the effect of insurer risks on profitability is conditional on regulation, using two main regulatory directives in the Ghanaian insurance market as a case study. Design/methodology/approach This study used the robust ordinary least square and random effect techniques in a panel data of 30 insurers from 2009 to 2015 to test the research hypothesis. Findings The results suggest that regulations on no credit premium and required capital have insignificant effects on profitability of insurers. On the contrary, this study documents evidence that both policies mitigate the effect of underwriting risk on profitability and suggests that regulations significantly mitigate the negative effect of underwriting risk to improve profitability. Practical implications The finding suggests that policymakers and regulators must continue to initiate, design and model regulations such that they help tame risk to improve the performance of insurers in Ghana. Originality/value This study provides first-time evidence on the role of regulations in controlling risks in a developing insurance market.

scholarly journals An In Vitro TORC1 Kinase Assay That Recapitulates the Gtr-Independent Glutamine-Responsive TORC1 Activation Mechanism on Yeast Vacuoles

2017 ◽  
Vol 37 (14) ◽  
Author(s):  
Mirai Tanigawa ◽  
Tatsuya Maeda
Keyword(s):  
Amino Acids ◽  
Nitrogen Sources ◽  
Small Gtpases ◽  
Activation Mechanism ◽  
Kinase Assay ◽  
Content Type ◽  
Vacuolar Protein ◽  
Vacuolar Membranes ◽  
First Time

ABSTRACT Evolutionarily conserved target of rapamycin (TOR) complex 1 (TORC1) responds to nutrients, especially amino acids, to promote cell growth. In the yeast Saccharomyces cerevisiae, various nitrogen sources activate TORC1 with different efficiencies, although the mechanism remains elusive. Leucine, and perhaps other amino acids, was reported to activate TORC1 via the heterodimeric small GTPases Gtr1-Gtr2, the orthologues of the mammalian Rag GTPases. More recently, an alternative Gtr-independent TORC1 activation mechanism that may respond to glutamine was reported, although its molecular mechanism is not clear. In studying the nutrient-responsive TORC1 activation mechanism, the lack of an in vitro assay hinders associating particular nutrient compounds with the TORC1 activation status, whereas no in vitro assay that shows nutrient responsiveness has been reported. In this study, we have developed a new in vitro TORC1 kinase assay that reproduces, for the first time, the nutrient-responsive TORC1 activation. This in vitro TORC1 assay recapitulates the previously predicted Gtr-independent glutamine-responsive TORC1 activation mechanism. Using this system, we found that this mechanism specifically responds to l-glutamine, resides on the vacuolar membranes, and involves a previously uncharacterized Vps34-Vps15 phosphatidylinositol (PI) 3-kinase complex and the PI-3-phosphate [PI(3)P]-binding FYVE domain-containing vacuolar protein Pib2. Thus, this system was proved to be useful for dissecting the glutamine-responsive TORC1 activation mechanism.

Sign in / Sign up

Export Citation Format

Share Document