Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infection with mucoid, alginate-producing strains of Pseudomonas aeruginosa is the leading cause of mortality among patients with cystic fibrosis. Alginate production by P. aeruginosa is not constitutive but is triggered by stresses such as starvation. The algR2 (also termed algQ) gene has been previously identified as being necessary for mucoidy; an algR2 mutant strain is unable to produce alginate when grown at 37 degrees C. We show here that the levels of phosphorylated succinyl coenzyme A synthetase (Scs) and nucleoside diphosphate kinase (Ndk), which form a complex in P. aeruginosa, are reduced in the algR2 mutant. We were able to correlate the lower level of phosphorylated Scs with a decrease in Scs activity. Western blots (immunoblots) also showed a decreased level of Ndk in the algR2 mutant, but the presence of another kinase activity sensitive to Tween 20 provides the missing Ndk function. The effect of AlgR2 on tricarboxylic acid (TCA) cycle enzymes appears to be specific for Scs, since none of the other TCA cycle enzymes measured showed a significant decrease in activity. Furthermore, the ability of the algR2 mutant to grow on TCA cycle intermediates, but not glucose, is impaired. These data indicate that AlgR2 is responsible for maintaining proper operation of the TCA cycle and energy metabolism.
 ...
PMID:Energy metabolism and alginate biosynthesis in Pseudomonas aeruginosa: role of the tricarboxylic acid cycle. 792 63

We have previously reported that two genes cloned from a cosmid library of Escherichia coli can restore mucoidy to an algR2 mutant of Pseudomonas aeruginosa. AlgR2 is a protein involved in the regulation of nucleoside diphosphate kinase (Ndk) as well as alginate synthesis in P. aeruginosa. One of the E. coli genes, rnk, encodes a 14.9 kDa protein with no homology to any other proteins. The other gene, sspA, encodes the stringent starvation protein, a regulatory protein involved in stationary-phase regulation and the stringent response of E. coli. While both rnk and sspA restored alginate production to the P. aeruginosa algR2 mutant, only rnk restored Ndk activity to the mutant. In this report, we have examined the effect of mutations in rnk and sspA on the levels of Ndk in E. coli. We find that a mutation in rnk drastically reduces the level of Ndk in E. coli. A mutation in sspA, however, affects the level of another nucleoside diphosphate kinase distinct from Ndk. The proteins can be easily distinguished from each other by their different affinities for nucleoside diphosphates (NDPs) and also by the differential effect of anti-Ndk antibodies on the reactions they catalyse. The ability of either of these two proteins to restore alginate synthesis in the algR2 mutant of P. aeruginosa demonstrates the importance of nucleoside triphosphate synthesis and energy metabolism for alginate synthesis. Additionally, a role for the stringent starvation protein (SspA) in the modulation of nucleoside triphosphate (NTP) levels in E. coli is also suggested from these experiments.
 ...
PMID:Regulation of nucleoside diphosphate kinase and an alternative kinase in Escherichia coli: role of the sspA and rnk genes in nucleoside triphosphate formation. 859 42

This study evaluated the link between swimming endurance and condition of Atlantic cod Gadus morhua that had been fed or starved during the 16 weeks preceding the tests, and assessed whether muscle metabolic capacities explain such links. The condition factor [(somatic mass x fork length(-3))x100] of starved cod was 0.54+/-0.1 whereas that of fed cod was 0.81+/-0.1. In white and red muscle, we measured four glycolytic enzymes: phosphofructokinase (PFK), pyruvate kinase (PK), creatine kinase (CK) and lactate dehydrogenase (LDH), two mitochondrial enzymes: cytochrome c oxidase (CCO) and citrate synthase (CS), a biosynthetic enzyme, nucleoside diphosphate kinase (NDPK), glycogen and protein levels and water content. Muscle samples were taken at three positions along the length of the fish; starvation affected the metabolic capacities of white muscle more than those of red muscle. The levels of glycolytic enzymes and glycogen changed more in white than red muscle during starvation. Both in fed and starved cod, muscle metabolic capacities varied with position along the fish; starvation reduced this longitudinal variation more in white than red muscle. In white muscle of fed cod, the glycolytic enzyme levels increased from head to tail, while in starved cod this longitudinal variation disappeared. In red muscle mitochondrial enzyme levels were highest in the caudal sample, but fewer differences were found for glycolytic enzymes. Swimming endurance was markedly affected by fish condition, with starved fish swimming only 30% of the time (and distance) of fed fish. This endurance was closely linked with the number of burst-coast movements during the test and the activity of CCO and LDH in white muscle. The number of burst-coast movements was significantly linked with condition factor and PFK activity in caudal red muscle and gill arch mass. Our data indicated that cod use both glycolytic and oxidative capacities to support endurance swimming. Furthermore, swimming endurance is linked with the metabolic capacities of red and white muscle.
 ...
PMID:Condition, prolonged swimming performance and muscle metabolic capacities of cod Gadus morhua. 1250 71

In response to iron limitation, Pseudomonas aeruginosa produces the fluorescent siderophore pyoverdine. Transcription of pyoverdine biosynthetic (pvd) genes is driven by the iron starvation sigma factor PvdS, which is negatively regulated by the Fur-Fe(II) holorepressor. We studied the effect of AlgQ, the Escherichia coli Rsd orthologue, on pyoverdine production by P. aeruginosa PAO1. AlgQ is a global regulatory protein which activates alginate, ppGpp, and inorganic polyphosphate synthesis through a cascade involving nucleoside diphosphate kinase (Ndk). AlgQ is also capable of interacting with region 4 of RpoD. In a reconstituted E. coli system, PvdS-dependent transcription from the pvdA promoter was doubled by the multicopy algQ gene. The P. aeruginosa DeltaalgQ mutant exhibited a moderate but reproducible reduction in pyoverdine production compared with wild-type PAO1, as a result of a decline in transcription of pvd genes. PvdS expression was not affected by the algQ mutation. Single-copy algQ fully restored pyoverdine production and expression of pvd genes in the DeltaalgQ mutant, while ndk did not. An increased intracellular concentration of RpoD mimicked the DeltaalgQ phenotype, whereas PvdS overexpression suppressed the algQ mutation. E. coli rsd could partially substitute for algQ in transcriptional modulation of pvd genes. We propose that AlgQ acts as an anti-sigma factor for RpoD, eliciting core RNA polymerase recruitment by PvdS and transcription initiation at pvd promoters. AlgQ provides a link between the pyoverdine and alginate regulatory networks. These systems have similarities in responsiveness and physiological function: both depend on alternative sigma factors, respond to nutrient starvation, and act as virulence determinants for P. aeruginosa.
 ...
PMID:Involvement of AlgQ in transcriptional regulation of pyoverdine genes in Pseudomonas aeruginosa PAO1. 1603 Feb 2

The growth rate of fish shows extensive plasticity in response to various environments. Metabolic responses of fish to excessive nutritional shortages such as starvation have been reported, but the effects of moderate nutrient shortage remain unclear. We examined expression levels of some genes related to ATP metabolism and to myogenesis, the RNA/DNA ratio, and the protein/DNA ratio of fish under different feeding conditions: a diet of 212-432% (frequent feeding, FR) or 32-82% (restricted feeding, RE) of initial body weight per week was supplied. The expression levels of nucleoside diphosphate kinase (NDK)-Z2, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and myogenin genes of RE fish were higher than those of FR fish, although the RNA/DNA ratio and the protein/DNA ratio were unaffected by the feeding amount. Moreover, expression levels of NDK-Z2 and GAPDH were upregulated to a greater extent than those for myogenin and myostatin 1 under restricted feeding. Together, our results show that gene expression is more sensitive to nutrient conditions of fish than traditional indicators such as the RNA/DNA ratio. The ATP metabolic system is more sensitive to moderate nutrient shortages than the myogenic system.
 ...
PMID:Feeding restriction alters expression of some ATP related genes more sensitively than the RNA/DNA ratio in zebrafish, Danio rerio. 1913 65

Gene duplication and divergence has emerged as an important aspect of developmental evolution. The genomes of Caenorhabditis nematodes encode an ancient family of PUF RNA-binding proteins. Most have been implicated in germline development, and are often redundant with paralogs of the same sub-family. An exception is Cbr-puf-2 (one of three Caenorhabditis briggsae PUF-2 sub-family paralogs), which is required for development past the second larval stage. Here, we provide a detailed functional characterization of Cbr-puf-2. The larval arrest of Cbr-puf-2 mutant animals is caused by inefficient breakdown of bacterial food, which leads to starvation. Cbr-puf-2 is required for the normal grinding cycle of the muscular terminal bulb during early larval stages, and is transiently expressed in this tissue. In addition, rescue of larval arrest reveals that Cbr-puf-2 also promotes normal vulval development. It is expressed in the anchor cell (which induces vulval fate) and vulval muscles, but not in the vulva precursor cells (VPCs) themselves. This contrasts with the VPC-autonomous repression of vulval development described for the Caenorhabditis elegans homologs fbf-1/2. These different roles for PUF proteins occur even as the vulva and pharynx maintain highly conserved anatomies across Caenorhabditis, indicating pervasive developmental system drift (DSD). Because Cbr-PUF-2 shares RNA-binding specificity with its paralogs and with C. elegans FBF, we suggest that functional novelty of RNA-binding proteins evolves through changes in the site of their expression, perhaps in concert with cis-regulatory evolution in target mRNAs.
 ...
PMID:Evolutionarily dynamic roles of a PUF RNA-binding protein in the somatic development of Caenorhabditis briggsae. 2425 95