scholarly journals A minimal model for metabolism-dependent chemotaxis in Rhodobacter sphaeroides

2014 ◽  
Vol 4 (6) ◽  
pp. 20140002 ◽  
Author(s):  
Sisi Fan ◽  
Robert G. Endres
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Rhodobacter Sphaeroides ◽  
Minimal Model ◽  
Environmental Chemicals ◽  
Signal Integration ◽  
The Core ◽  
Essential Components ◽  
Chemotactic Behaviour ◽  
Cellular Movement

Chemotaxis is vital cellular movement in response to environmental chemicals. Unlike the canonical chemotactic pathway in Escherichia coli , Rhodobacter sphaeroides has both transmembrane and cytoplasmic sensory clusters, with the latter possibly interacting with essential components in the electron transport system. However, the effect of the cytoplasmic sensor and the mechanism of signal integration from both sensory clusters remain unclear. Based on a minimal model of the chemotaxis pathway in this species, we show that signal integration at the motor level produces realistic chemotactic behaviour in line with experimental observations. Our model also suggests that the core pathway of R. sphaeroides , at least its ancestor, may represent a metabolism-dependent selective stopping strategy, which alone can steer cells to favourable environments. Our results not only clarify the potential roles of the two sensory clusters but also put in question the current definitions of attractants and repellents.

scholarly journals A Rhodobacter sphaeroides Protein Mechanistically Similar to Escherichia coli DksA Regulates Photosynthetic Growth

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Christopher W. Lennon ◽  
Kimberly C. Lemmer ◽  
Jessica L. Irons ◽  
Max I. Sellman ◽  
Timothy J. Donohue ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Structure Function ◽  
Rhodobacter Sphaeroides ◽  
Fatty Acid Content ◽  
Regulatory Protein ◽  
Growth Conditions ◽  
Globular Domain ◽  
Content Type ◽  
E Coli

ABSTRACTDksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacteriumEscherichia coliand for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly relatedRhodobacter sphaeroides, an alphaproteobacterium. RSP2654 is 42% identical and similar in length toE. coliDksA but lacks the Zn finger motif of theE. coliDksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of anE. colistrain lacking thedksAgene and modulates transcriptionin vitrowithE. coliRNA polymerase (RNAP) similarly toE. coliDksA. RSP2654 reduces RNAP-promoter complex stabilityin vitrowith RNAPs fromE. coliorR. sphaeroides, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity toE. coliDksA (DksAEc), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksARsp. Our work suggests that DksARsphas distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp.IMPORTANCEThe role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis inRhodobacter sphaeroides. The study of DksARsp, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.

Mass Spectrometry of Escherichia coli RNA PolymeraseInteractions of the Core Enzyme with σ70 and Rsd Protein

Structure ◽  
2004 ◽  
Vol 12 (2) ◽  
pp. 269-275 ◽  
Author(s):  
L ILAG ◽  
L WESTBLADE ◽  
C DESHAYES ◽  
A KOLB ◽  
S BUSBY ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Escherichia Coli ◽  
The Core ◽  
Core Enzyme

scholarly journals A mutation affecting a second component of the F0 portion of the magnesium ion-stimulated adenosine triphosphatase of Escherichia coli K12. The uncC424 allele

1977 ◽  
Vol 164 (1) ◽  
pp. 193-198 ◽  
Author(s):  
F Gibson ◽  
G B Cox ◽  
J A Downie ◽  
J Radik
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Fluorescence Quenching ◽  
Mutant Strain ◽  
Mutant Allele ◽  
Adenosine Triphosphatase ◽  
Magnesium Ion ◽  
New Mutation ◽  
Similar Phenotype

A new mutant strain of Escherichia coli in which phosphorylation is uncoupled from electron transport was isolated. The new mutant strain has a similar phenotype to the uncB mutant described previously; results from reconstitution experiments in vitro indicate that the new mutation also affects a component of the F0 portion of the Mg2+-stimulated adenosine triphosphatase. A method was developed to incorporate mutant unc alleles into plasmids. Partial diploid strains were prepared in which the uncB402 allele was incorporated into the plasmid and the new unc mutation into the chromosome, or vice versa. Complementation between the mutant unc alleles was indicated by growth on succinate, growth yields on glucose, ATP-dependent transhydrogenase activities, ATP-induced atebrin-fluorescence quenching and oxidative-phosphorylation measurements. The gene in which the new mutation occurs is therefore distinct from the uncB gene, and the mutant allele was designated uncC424.

scholarly journals Physiological Evidence for Isopotential Tunneling in the Electron Transport Chain of Methane-Producing Archaea

2017 ◽  
Vol 83 (18) ◽  
Author(s):  
Nikolas Duszenko ◽  
Nicole R. Buan
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Electron Transport Chain ◽  
Methanosarcina Barkeri ◽  
Metabolic Efficiency ◽  
Methanosarcina Acetivorans ◽  
Content Type ◽  
Transport Chain

ABSTRACT Many, but not all, organisms use quinones to conserve energy in their electron transport chains. Fermentative bacteria and methane-producing archaea (methanogens) do not produce quinones but have devised other ways to generate ATP. Methanophenazine (MPh) is a unique membrane electron carrier found in Methanosarcina species that plays the same role as quinones in the electron transport chain. To extend the analogy between quinones and MPh, we compared the MPh pool sizes between two well-studied Methanosarcina species, Methanosarcina acetivorans C2A and Methanosarcina barkeri Fusaro, to the quinone pool size in the bacterium Escherichia coli. We found the quantity of MPh per cell increases as cultures transition from exponential growth to stationary phase, and absolute quantities of MPh were 3-fold higher in M. acetivorans than in M. barkeri. The concentration of MPh suggests the cell membrane of M. acetivorans, but not of M. barkeri, is electrically quantized as if it were a single conductive metal sheet and near optimal for rate of electron transport. Similarly, stationary (but not exponentially growing) E. coli cells also have electrically quantized membranes on the basis of quinone content. Consistent with our hypothesis, we demonstrated that the exogenous addition of phenazine increases the growth rate of M. barkeri three times that of M. acetivorans. Our work suggests electron flux through MPh is naturally higher in M. acetivorans than in M. barkeri and that hydrogen cycling is less efficient at conserving energy than scalar proton translocation using MPh. IMPORTANCE Can we grow more from less? The ability to optimize and manipulate metabolic efficiency in cells is the difference between commercially viable and nonviable renewable technologies. Much can be learned from methane-producing archaea (methanogens) which evolved a successful metabolic lifestyle under extreme thermodynamic constraints. Methanogens use highly efficient electron transport systems and supramolecular complexes to optimize electron and carbon flow to control biomass synthesis and the production of methane. Worldwide, methanogens are used to generate renewable methane for heat, electricity, and transportation. Our observations suggest Methanosarcina acetivorans, but not Methanosarcina barkeri, has electrically quantized membranes. Escherichia coli, a model facultative anaerobe, has optimal electron transport at the stationary phase but not during exponential growth. This study also suggests the metabolic efficiency of bacteria and archaea can be improved using exogenously supplied lipophilic electron carriers. The enhancement of methanogen electron transport through methanophenazine has the potential to increase renewable methane production at an industrial scale.

scholarly journals To catch a hijacker: abundance, evolution and genetic diversity of P4-like bacteriophage satellites

2021 ◽  
Vol 377 (1842) ◽  
Author(s):  
Jorge A. Moura de Sousa ◽  
Eduardo P. C. Rocha
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Core Genome ◽  
Mobile Genetic Elements ◽  
Abundance Distribution ◽  
Theme Issue ◽  
Genetic Elements ◽  
The Core ◽  
Antagonistic Interactions ◽  
Variable Genes

Bacteriophages (phages) are bacterial parasites that can themselves be parasitized by phage satellites. The molecular mechanisms used by satellites to hijack phages are sometimes understood in great detail, but the origins, abundance, distribution and composition of these elements are poorly known. Here, we show that P4-like elements are present in more than 30% of the genomes of Enterobacterales, and in almost half of those of Escherichia coli , sometimes in multiple distinct copies. We identified over 1000 P4-like elements with very conserved genetic organization of the core genome and a few hotspots with highly variable genes. These elements are never found in plasmids and have very little homology to known phages, suggesting an independent evolutionary origin. Instead, they are scattered across chromosomes, possibly because their integrases are often exchanged with other elements. The rooted phylogenies of hijacking functions are correlated and suggest longstanding coevolution. They also reveal broad host ranges in P4-like elements, as almost identical elements can be found in distinct bacterial genera. Our results show that P4-like phage satellites constitute a very distinct, widespread and ancient family of mobile genetic elements. They pave the way for studying the molecular evolution of antagonistic interactions between phages and their satellites. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.

scholarly journals Novel Activity of Rhodobacter sphaeroides Spheroidene Monooxygenase CrtA Expressed in Escherichia coli

2010 ◽  
Vol 76 (21) ◽  
pp. 7328-7331 ◽  
Author(s):  
Pyung Cheon Lee ◽  
Erik Holtzapple ◽  
Claudia Schmidt-Dannert
Keyword(s):  
Escherichia Coli ◽  
Hydroxy Group ◽  
Rhodobacter Sphaeroides ◽  
Keto Group ◽  
P450 Enzyme ◽  
New Type

ABSTRACT The spheroidene monooxygenase CrtA of Rhodobacter sphaeroides introduces a keto group and/or hydroxy group at the ends of nonnative substrates in Escherichia coli, resulting in the production of novel oxocarotenoids. The heme-containing CrtA is not a P450 enzyme but a new type of oxygenase.

How to Bend but Not Break an Empirically Supported Treatment for Anxiety in Youth

2021 ◽  
pp. 175-210
Author(s):  
Lara S. Rifkin ◽  
Lindsay Myerberg ◽  
Elizabeth A. Gosch ◽  
Lesley A. Norris ◽  
Margaret E. Crane ◽  
...  
Keyword(s):  
Behavioral Therapy ◽  
Developmental Level ◽  
Empirically Supported Treatment ◽  
The Core ◽  
Empirically Supported ◽  
Youth Anxiety ◽  
Essential Components ◽  
Self Talk ◽  
Core Components ◽  
Building Rapport

This chapter addresses the treatment of youth anxiety. Cognitive behavioral therapy (CBT) for youth anxiety, as illustrated by the Coping Cat program, is implemented flexibly based on considerations including age/developmental level, co-occurring disorders, socioeconomic status, and cultural factors to enhance outcomes. For fidelity, the program adheres to key components: building rapport, providing psychoeducation about anxiety, addressing anxious self-talk, conducting exposures, assigning homework, and providing rewards/praise. The essential components, however, are applied with flexibility. Ultimately, research is needed to evaluate strategies to increase continued fidelity to the core components of treatment. Peer consultation and supervision may be valuable for maintaining fidelity while flexibly applying the program to a specific client.

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