scholarly journals Evolution of the calcium feedback steps of vertebrate phototransduction

Open Biology ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 180119 ◽  
Author(s):  
Trevor D. Lamb ◽  
David M. Hunt
Keyword(s):  
Feedback Loop ◽  
Regulatory System ◽  
Feedback Regulation ◽  
Photoreceptor Cells ◽  
Gene Duplications ◽  
Receptor Kinase ◽  
Low Light ◽  
Protein Receptor ◽  
Vertebrate Photoreceptor ◽  
Genes Encoding

We examined the genes encoding the proteins that mediate the Ca-feedback regulatory system in vertebrate rod and cone phototransduction. These proteins comprise four families: recoverin/visinin, the guanylyl cyclase activating proteins (GCAPs), the guanylyl cyclases (GCs) and the sodium/calcium-potassium exchangers (NCKXs). We identified a paralogon containing at least 36 phototransduction genes from at least fourteen families, including all four of the families involved in the Ca-feedback loop (recoverin/visinin, GCAPs, GCs and NCKXs). By combining analyses of gene synteny with analyses of the molecular phylogeny for each of these four families of genes for Ca-feedback regulation, we have established the likely pattern of gene duplications and losses underlying the expansion of isoforms, both before and during the two rounds of whole-genome duplication (2R WGD) that occurred in early vertebrate evolution. Furthermore, by combining our results with earlier evidence on the timing of duplication of the visual G-protein receptor kinase genes, we propose that specialization of proto-vertebrate photoreceptor cells for operation at high and low light intensities preceded the emergence of rhodopsin, which occurred during 2R WGD.

scholarly journals F-actin homeostasis through transcriptional regulation and proteasome-mediated proteolysis

2018 ◽  
Vol 115 (28) ◽  
pp. E6487-E6496 ◽  
Author(s):  
Masayuki Onishi ◽  
Kresti Pecani ◽  
Taylor Jones ◽  
John R. Pringle ◽  
Frederick R. Cross
Keyword(s):  
Feedback Loop ◽  
Transcriptional Response ◽  
Regulatory System ◽  
Normal Growth ◽  
Ubiquitin Proteasome System ◽  
Growth Conditions ◽  
Proliferating Cells ◽  
Genes Encoding ◽  
Ubiquitin Proteasome ◽  
Actin Homeostasis

Many organisms possess multiple and often divergent actins whose regulation and roles are not understood in detail. For example, Chlamydomonas reinhardtii has both a conventional actin (IDA5) and a highly divergent one (NAP1); only IDA5 is expressed in normal proliferating cells. We showed previously that the drug latrunculin B (LatB) causes loss of filamentous (F-) IDA5 and strong up-regulation of NAP1, which then provides essential actin function(s) by forming LatB-resistant F-NAP1. RNA-sequencing analyses now show that this up-regulation of NAP1 reflects a broad transcriptional response, much of which depends on three proteins (LAT1, LAT2, and LAT3) identified previously as essential for NAP1 transcription. Many of the LAT-regulated genes contain a putative cis-acting regulatory site, the “LRE motif.” The LatB transcriptional program appears to be activated by loss of F-IDA5 and deactivated by formation of F-NAP1, thus forming an F-actin–dependent negative-feedback loop. Multiple genes encoding proteins of the ubiquitin-proteasome system are among those induced by LatB, resulting in rapid degradation of IDA5 (but not NAP1). Our results suggest that IDA5 degradation is functionally important because nonpolymerizable LatB-bound IDA5 interferes with the formation of F-NAP1. The genes for the actin-interacting proteins cofilin and profilin are also induced. Cofilin induction may further the clearance of IDA5 by promoting the scission of F-IDA5, whereas profilin appears to function in protecting monomeric IDA5 from degradation. This multifaceted regulatory system allows rapid and quantitative turnover of F-actin in response to cytoskeletal perturbations and probably also maintains F-actin homeostasis under normal growth conditions.

scholarly journals Genetic Analysis of Colistin Resistance in Salmonella enterica Serovar Typhimurium

2009 ◽  
Vol 53 (6) ◽  
pp. 2298-2305 ◽  
Author(s):  
Song Sun ◽  
Aurel Negrea ◽  
Mikael Rhen ◽  
Dan I. Andersson
Keyword(s):  
Mutation Rate ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Clinical Settings ◽  
Missense Mutations ◽  
Regulator Protein ◽  
Serovar Typhimurium ◽  
Sensor Kinases ◽  
Genes Encoding

ABSTRACT Colistin is a cyclic cationic peptide that kills gram-negative bacteria by interacting with and disrupting the outer membrane. We isolated 44 independent mutants in Salmonella enterica serovar Typhimurium with reduced susceptibility to colistin and identified 27 different missense mutations located in the pmrA and pmrB genes (encoding the regulator and sensor of a two-component regulatory system) that conferred increased resistance. By comparison of the two homologous sensor kinases, PmrB and EnvZ, the 22 missense mutations identified in pmrB were shown to be located in four different structural domains of the protein. All five pmrA mutations were located in the phosphate receiver domain of the regulator protein. The mutants appeared at a mutation rate of 0.6 × 10−6 per cell per generation. The MICs of colistin for the mutants increased 2- to 35-fold, and the extent of killing was reduced several orders of magnitude compared to the susceptible strain. The growth rates of the mutants were slightly reduced in both rich medium and M9-glycerol minimal medium, whereas growth in mice appeared unaffected by the pmrA and pmrB mutations. The low fitness costs and the high mutation rate suggest that mutants with reduced susceptibility to colistin could emerge in clinical settings.

AGONIST ACTIVATED ADRENOCORTICOTROPIN RECEPTOR INTERNALIZES VIA A CLATHRIN-MEDIATED G PROTEIN RECEPTOR KINASE DEPENDENT MECHANISM

2002 ◽  
Vol 28 (4) ◽  
pp. 281-289 ◽  
Author(s):  
A. H. Baig ◽  
F. M. Swords ◽  
M. Szaszák ◽  
P. J. King ◽  
L. Hunyady ◽  
...  
Keyword(s):  
G Protein ◽  
Receptor Kinase ◽  
Protein Receptor ◽  
Dependent Mechanism

scholarly journals Variable Expressions of Staphylococcus aureus Bicomponent Leucotoxins Semiquantified by Competitive Reverse Transcription-PCR

2000 ◽  
Vol 66 (9) ◽  
pp. 3931-3938 ◽  
Author(s):  
St�phane Bronner ◽  
Patricia Stoessel ◽  
Alain Gravet ◽  
Henri Monteil ◽  
Gilles Pr�vost
Keyword(s):  
Staphylococcus Aureus ◽  
Reverse Transcription ◽  
Regulatory System ◽  
Optimization Procedure ◽  
Reverse Transcription Pcr ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Specific Mrnas ◽  
Casamino Acids ◽  
Global Regulatory System

ABSTRACT A competitive reverse transcription-PCR method was developed for the semiquantitation of the expression of genes encoding bicomponent leucotoxins of Staphylococcus aureus, e.g., Panton-Valentine leucocidin (lukPV), gamma-hemolysin (hlgA and hlgCB), and LukE-LukD (lukED). The optimization procedure included RNA preparation; reverse transcription; the use of various amounts of enzymes, antisense primer, and RNA; and the final amplification chain reaction. Reproducible results were obtained, with sensitivity for detection of cDNA within the range of 1 mRNA/104 CFU to 102 mRNA/CFU, depending on the gene. Both specific mRNAs were more significantly expressed at the late-exponential phase of growth. Expression was about 100-fold higher in yeast extract-Casamino Acids-pyruvate medium than in heart infusion medium. Expression of the widely distributed gamma-hemolysin locus in the NTCC 8178 strain was around 10-fold diminished compared with that in the ATCC 49775 strain. Because of the lower level of hlgA expression, the corresponding protein, which is generally not abundant in culture supernatant, should be investigated for its contribution to the leucotoxin-associated virulence. The agr, sar, and agr sar mutant strains revealed a great dependence with regard to leucotoxin expression on the global regulatory system inS. aureus, except that expression of hlgA was not affected in the agr mutant.

The Physiology of Body Weight Regulation: Relevance to the Etiology of Obesity in Children

PEDIATRICS ◽  
1998 ◽  
Vol 101 (Supplement_2) ◽  
pp. 525-539 ◽  
Author(s):  
Michael Rosenbaum ◽  
Rudolph L. Leibel
Keyword(s):  
United States ◽  
Body Weight ◽  
Environmental Factors ◽  
Regulatory System ◽  
The United States ◽  
Genetic Changes ◽  
Adult Body ◽  
Genes Encoding ◽  
Prevalence Of Obesity ◽  
Obesity In Children

The prevalence of obesity in children and adults in the United States has increased by more than 30% over the past decade. Recent studies of the physiology and molecular genetics of obesity in humans have provided evidence that body weight (fat) is regulated. Some of the genes encoding the molecular components of this regulatory system have been isolated from rodents. The increasing prevalence of obesity in the United States apparently represents the interaction of these genes with an environment that encourages a sedentary lifestyle and consumption of calories. The rapid increase in the prevalence of obesity emphasizes the role of environmental factors, because genetic changes could not occur at this rate. Thus, understanding of the relevant genes and how their effects are mediated by environment and development should lead to more effective prophylaxis and therapy of obesity. Although no clear environmental factors have been identified as causative of obesity, the rapid increases in the prevalence of obesity and the seeming voluntary immutability of adult body fatness can be taken as tacit evidence that the pediatric environment can be altered in a way that affects adult body weight.

scholarly journals Putative VanRS-Like Two-Component Regulatory System Associated with the Inducible Glycopeptide Resistance Cluster of Paenibacillus popilliae

2005 ◽  
Vol 49 (7) ◽  
pp. 2625-2633 ◽  
Author(s):  
Henry Fraimow ◽  
Christopher Knob ◽  
Inmaculada A. Herrero ◽  
Robin Patel
Keyword(s):  
Regulatory System ◽  
Growth Curves ◽  
Upstream Region ◽  
Bacillus Halodurans ◽  
Human Pathogens ◽  
Glycopeptide Resistance ◽  
Transposase Gene ◽  
Two Component ◽  
Genes Encoding ◽  
Paenibacillus Lentimorbus

ABSTRACT Paenibacillus popilliae contains vanF encoding a putative d-Ala:d-lactate (d-Lac) ligase, VanF, as part of the vanY F Z F H F FX F cluster that is similar in structure to the enterococcal vanA and vanB clusters. Using growth curves, we demonstrated that vancomycin resistance in P. popilliae is inducible. Using degenerate oligonucleotides targeted at bacterial cell wall ligases, we identified a second ligase gene with features of a d-Ala:d-Ala ligase in both P. popilliae and the related, vancomycin-susceptible, Paenibacillus lentimorbus. The 3,380-bp region upstream of vanY F Z F H F FX F in P. popilliae ATCC 14706 was sequenced and found to contain genes encoding a putative two-component regulator, VanRFSF, similar to VanRS but more closely related to a family of two-component regulators linked to VanY-like carboxypeptidases in several glycopeptide-susceptible Bacillus species. This upstream region also included a transposase similar to a transposase found in Bacillus halodurans and, in some strains, a 99-bp insertion of unknown function with 95% nucleotide identity to a portion of the Tn1546 transposase gene. Analysis of glycopeptide resistance-associated clusters from soil and/or insect-dwelling organisms may provide important clues to the molecular evolution of acquired glycopeptide resistance elements in human pathogens.

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