Sequence of the preprotoxin dsRNA gene of type I killer yeast: Multiple processing events produce a two-component toxin

Cell ◽  
1984 ◽  
Vol 36 (3) ◽  
pp. 741-751 ◽  
Author(s):  
Keith A. Bostian ◽  
Quentin Elliott ◽  
Howard Bussey ◽  
Virginia Bum ◽  
A.I. Smith ◽  
...  
Keyword(s):  
Type I ◽  
Killer Yeast ◽  
Two Component ◽  
Multiple Processing

scholarly journals MisR/MisS Two-Component Regulon in Neisseria meningitidis

2007 ◽  
Vol 76 (2) ◽  
pp. 704-716 ◽  
Author(s):  
Yih-Ling Tzeng ◽  
Charlene M. Kahler ◽  
Xinjian Zhang ◽  
David S. Stephens
Keyword(s):  
Neisseria Meningitidis ◽  
Target Genes ◽  
Inner Core ◽  
Consensus Sequence ◽  
Meningococcal Infection ◽  
Type I ◽  
Mobility Shift ◽  
Iron Assimilation ◽  
Wide Range ◽  
Two Component

ABSTRACT Two-component regulatory systems are involved in processes important for bacterial pathogenesis. Inactivation of the misR/misS system in Neisseria meningitidis results in the loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. One hundred seventeen (78 up-regulated and 39 down-regulated) potential regulatory targets of the MisR/MisS (MisR/S) system were identified by transcriptional profiling of the NMBmisR mutant and the parental wild-type meningococcal strain NMB. The regulatory effect was further confirmed in a subset of target genes by quantitative real-time PCR and β-galactosidase transcriptional fusion reporter assays. The MisR regulon includes genes encoding proteins necessary for protein folding in the bacterial cytoplasm and periplasm, transcriptional regulation, metabolism, iron assimilation, and type I protein transport. Mutation in the MisR/S system caused increased sensitivity to oxidative stress and also resulted in decreased susceptibility to complement-mediated killing by normal human serum. To identify the direct targets of MisR regulation, electrophoretic mobility shift assays were carried out using purified MisR-His6 protein. Among 22 genes examined, misR directly interacted with 14 promoter regions. Six promoters were further investigated by DNase I protection assays, and a MisR-binding consensus sequence was proposed. Thus, the direct regulatory targets of MisR and the minimal regulon of the meningococcal MisR/S two-component signal transduction system were characterized. These data indicate that the MisR/S system influences a wide range of biological functions in N. meningitidis either directly or via intermediate regulators.

scholarly journals CRISPR-Cas immunity repressed by a biofilm-activating pathway inPseudomonas aeruginosa

2019 ◽  
Author(s):  
Adair L. Borges ◽  
Bardo Castro ◽  
Sutharsan Govindarajan ◽  
Tina Solvik ◽  
Veronica Escalante ◽  
...  
Keyword(s):  
Genetic Screen ◽  
Type I ◽  
Two Component System ◽  
Component System ◽  
Forward Genetic Screen ◽  
Immune Systems ◽  
Adaptive Immune ◽  
Biofilm Production ◽  
Two Component ◽  
Adaptive Immune Systems

CRISPR-Cas systems are adaptive immune systems that protect bacteria from bacteriophage (phage) infection. To provide immunity, RNA-guided protein surveillance complexes recognize foreign nucleic acids, triggering their destruction by Cas nucleases. While the essential requirements for immune activity are well understood, the physiological cues that regulate CRISPR-Cas expression are not. Here, a forward genetic screen identifies a two-component system (KinB/AlgB), previously characterized in regulatingPseudomonas aeruginosavirulence and biofilm establishment, as a regulator of the biogenesis and activity of the Type I-F CRISPR-Cas system. Downstream of the KinB/AlgB system, activators of biofilm production AlgU (a σEorthologue) and AlgR, act as repressors of CRISPR-Cas activity during planktonic and surface-associated growth. AmrZ, another biofilm activator, functions as a surface-specific repressor of CRISPR-Cas immunity.Pseudomonasphages and plasmids have taken advantage of this regulatory scheme, and carry hijacked homologs of AmrZ, which are functional CRISPR-Cas repressors. This suggests that while CRISPR-Cas regulation may be important to limit self-toxicity, endogenous repressive pathways represent a vulnerability for parasite manipulation.

scholarly journals Growth after the streaming instability

2019 ◽  
Vol 624 ◽  
pp. A114 ◽  
Author(s):  
Beibei Liu ◽  
Chris W. Ormel ◽  
Anders Johansen
Keyword(s):  
Dynamical Evolution ◽  
Bimodal Distribution ◽  
Stokes Number ◽  
Volume Density ◽  
Mass Star ◽  
Type I ◽  
Solar Mass ◽  
Streaming Instability ◽  
Two Component ◽  
Self Gravity

Context. Streaming instability is a key mechanism in planet formation, clustering pebbles into planetesimals with the help of self-gravity. It is triggered at a particular disk location where the local volume density of solids exceeds that of the gas. After their formation, planetesimals can grow into protoplanets by feeding from other planetesimals in the birth ring as well as by accreting inwardly drifting pebbles from the outer disk. Aims. We aim to investigate the growth of planetesimals into protoplanets at a single location through streaming instability. For a solar-mass star, we test the conditions under which super-Earths are able to form within the lifetime of the gaseous disk. Methods. We modified the Mercury N-body code to trace the growth and dynamical evolution of a swarm of planetesimals at a distance of 2.7 AU from the star. The code simulates gravitational interactions and collisions among planetesimals, gas drag, type I torque, and pebble accretion. Three distributions of planetesimal sizes were investigated: (i) a mono-dispersed population of 400 km radius planetesimals, (ii) a poly-dispersed population of planetesimals from 200 km up to 1000 km, (iii) a bimodal distribution with a single runaway body and a swarm of smaller, 100 km size planetesimals. Results. The mono-dispersed population of 400 km size planetesimals cannot form protoplanets of a mass greater than that of the Earth. Their eccentricities and inclinations are quickly excited, which suppresses both planetesimal accretion and pebble accretion. Planets can form from the poly-dispersed and bimodal distributions. In these circumstances, it is the two-component nature that damps the random velocity of the large embryo through the dynamical friction of small planetesimals, allowing the embryo to accrete pebbles efficiently when it approaches 10−2 M⊕. Accounting for migration, close-in super-Earth planets form. Super-Earth planets are likely to form when the pebble mass flux is higher, the disk turbulence is lower, or the Stokes number of the pebbles is higher. Conclusions. For the single site planetesimal formation scenario, a two-component mass distribution with a large embryo and small planetesimals promotes planet growth, first by planetesimal accretion and then by pebble accretion of the most massive protoplanet. Planetesimal formation at single locations such as ice lines naturally leads to super-Earth planets by the combined mechanisms of planetesimal accretion and pebble accretion.

scholarly journals Two-Component Regulators ControlhilAExpression by ControllingfimZandhilEExpression within Salmonella enterica Serovar Typhimurium

2014 ◽  
Vol 83 (3) ◽  
pp. 978-985 ◽  
Author(s):  
M. Aaron Baxter ◽  
Bradley D. Jones
Keyword(s):  
Transcriptional Activator ◽  
Negative Regulator ◽  
Host Cells ◽  
Type I ◽  
Dependent Manner ◽  
Content Type ◽  
Regulatory Systems ◽  
Two Component ◽  
Serovar Typhimurium ◽  
Type I Fimbriae

Salmonellae initiate disease through the invasion of host cells within the intestine. This ability to invade requires the coordinated action of numerous genes, many of which are found withinSalmonellapathogenicity island 1 (SPI-1). The key to this process is the ability of the bacteria to respond to the environment, thereby upregulating the necessary genes under optimal conditions. Central to the control of SPI-1 is the transcriptional activatorhilA. Work has identified at least 10 different activators and 8 different repressors responsible for the control ofhilA. We have previously shown thathilEis aSalmonella-specific negative regulator that is able to represshilAexpression and invasion. Additionally,fimZ, a transcriptional activator responsible for the expression of type I fimbriae as well as flagellar genes, has also been implicated in this process.fimZis homologous to response regulators from other two-component regulatory systems, although a sensor for the system has not been identified. ThephoPQandphoBRregulons are both two-component systems that negatively affecthilAexpression, although the mechanism of action has not been determined. Our results show that PhoBR is capable of inducingfimZexpression, whereas PhoPQ does not affectfimZexpression but does upregulatehilEin an FimZ-dependent manner. Therefore, phosphate (sensed by PhoBR) and magnesium (sensed by PhoPQ) levels are important in controllinghilAexpression levels whenSalmonellais in the intestinal environment.

FEEDBACK-INDUCED COMPLEX DYNAMICS IN A TWO-COMPONENT REGULATORY CIRCUIT

2012 ◽  
Vol 22 (03) ◽  
pp. 1250059 ◽  
Author(s):  
HUAHAI QIU ◽  
TIANSHOU ZHOU
Keyword(s):  
Negative Feedback ◽  
First Passage Time ◽  
Stable Limit Cycle ◽  
Feedback Loops ◽  
Type I ◽  
Stable Limit ◽  
Type Ii ◽  
Negative Feedback Loops ◽  
Two Component ◽  
Positive And Negative Feedback

Coupled positive and negative feedback loops form an essential building block of cellular signaling pathways, but the dynamics of such a system remain to be fully explored. Here, we systematically analyze a two-component circuit with interlinked positive and negative feedback loops, focusing on feedback-induced dynamics and their mechanisms. We show that feedbacks can induce monostability, oscillation, and excitability as well as the coexistence of two attractors (including that of two different stable steady states (called Type-I bistability) and that of both a stable steady state and a stable limit cycle (called Type-II bistability)). In particular for Type-II bistability, we find that feedback-controlled molecular noise can induce stochastic switching between two different attractors, and that the first passage time between them exhibits a multi-peak distribution. These investigations provide insights for understanding the biological functions of coupled positive and negative feedback circuits from the viewpoint of dynamics.

BIFURCATIONS IN A HUMAN MIGRATION MODEL OF SCHEURLE–SEYDEL TYPE-I: TURING BIFURCATION

2003 ◽  
Vol 13 (05) ◽  
pp. 1303-1308 ◽  
Author(s):  
SÁNDOR KOVÁCS
Keyword(s):  
Graduate Programs ◽  
Critical Value ◽  
Human Migration ◽  
Fickian Diffusion ◽  
Type I ◽  
Two Component System ◽  
Component System ◽  
Turing Bifurcation ◽  
Cross Diffusion ◽  
Two Component

In this paper we consider a model for the behavior of students in graduate programs at neighboring universities which is a modified form of the model proposed by [Scheurle & Seydel, 2000], and observe that the stationary solution of this two-component system becomes unstable in the presence of diffusion. We assume that both types of individuals are continuously distributed throughout a bounded two-dimensional spatial domain of two types (regular hexagon and rhombus), across whose boundaries there is no migration, and which simultaneously undergo simple (Fickian) diffusion but the spatial flow is influenced not only by its own but also by the other's density (cross diffusion). We will show that at a critical value of a parameter a Turing bifurcation takes place: a spatially nonhomogenous solution (pattern) arises.

scholarly journals RaxH/RaxR: A Two-Component Regulatory System in Xanthomonas oryzae pv. oryzae Required for AvrXa21 Activity

2004 ◽  
Vol 17 (6) ◽  
pp. 602-612 ◽  
Author(s):  
Saul Burdman ◽  
Yuwei Shen ◽  
Sang-Won Lee ◽  
Qinzhong Xue ◽  
Pamela Ronald
Keyword(s):  
Response Regulator ◽  
Sulfur Metabolism ◽  
Regulatory System ◽  
Xanthomonas Oryzae ◽  
Expression Vectors ◽  
Type I ◽  
Wild Type ◽  
Two Component ◽  
Genes Encoding ◽  
Null Mutants

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight, one of the most serious diseases in rice. X. oryzae pv. oryzae Philippine race 6 (PR6) strains are unable to establish infection in rice lines expressing the resistance gene Xa21. Although the pathogen-associated molecule that triggers the Xa21-mediated defense response (AvrXa21) is unknown, six rax (required for AvrXa21 activity) genes encoding proteins involved in sulfur metabolism and Type I secretion were recently identified. Here, we report on the identification of two additional rax genes, raxR and raxH, which encode a response regulator and a histidine protein kinase of two-component regulatory systems, respectively. Null mutants of PR6 strain PXO99 that are impaired in either raxR, raxH, or both cause lesions significantly longer and grow to significantly higher levels than does the wild-type strain in Xa21-rice leaves. Both raxR and raxH mutants are complemented to wild-type levels of AvrXa21 activity by introduction of expression vectors carrying raxR and raxH, respectively. These null mutants do not affect AvrXa7 and AvrXa10 activities, as observed in inoculation experiments with Xa7- and Xa10-rice lines. Western blot and raxR/gfp promoter-reporter analyses confirmed RaxR expression in X. oryzae pv. oryzae. The results of promoter-reporter studies also suggest that the previously identified raxSTAB operon is a target for RaxH/RaxR regulation. Characterization of the RaxH/RaxR system provides new opportunities for understanding the specificity of the X. oryzae pv. oryzae-Xa21 interaction and may contribute to the identification of AvrXa21.

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