Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.1.79 (hormone-sensitive lipase)
2,163 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine possible genetic influences on the steady-state concentrations of several key transcription factor transcripts and the transcript concentrations for adipocyte-characteristic proteins, young, genetically obese and lean pigs were given ad libitum access or feed or were restrictively fed at 50% of ad libitum intake for 5 wk. Obese pigs were smaller and fatter than lean pigs, whether intake was ad libitum or restrictive. Plasma protein, albumin, and cholesterol concentrations were greater in obese than in lean pigs. Plasma NEFA, blood urea nitrogen, triacylglycerols, and postprandial glucose and insulin concentrations were less (P < .02) in pigs fed restrictively than in pigs with ad libitum access to feed, regardless of genetic group. The adipose tissue glucose transporter 4, fatty acid synthase, and leptin transcript concentrations were greater (P < .05) in obese than in lean pigs. The CCAAT/enhancer binding proteins beta and alpha, adipocyte fatty acid binding protein, hormone-sensitive lipase, and the beta1-adrenergic receptor transcript concentrations tended (P < . 10) to be greater in adipose tissue from obese than in that from lean pigs. Several other transcripts were numerically greater in obese than in lean pigs. The data collectively suggest that messenger RNA concentration for several adipose tissue proteins is a contributing factor to the excess fat deposition in these obese pigs. Restricted feeding did not change the concentration of any transcript except that for adipocyte fatty acid binding protein, which was reduced. The accretion of fat was markedly reduced in the restrictively fed pigs, but this diminution does not seem to be regulated by modulation of messenger RNA concentration.
...
PMID:Effect of feed restriction on adipose tissue transcript concentrations in genetically lean and obese pigs. 1078 83

Acyl-homoserine lactones (acyl-HSLs) serve as dedicated cell-to-cell signaling molecules in many species of the class Proteobacteria. We have addressed the question of whether these compounds can be degraded biologically. A motile, rod-shaped bacterium was isolated from soil based upon its ability to utilize N-(3-oxohexanoyl)-L-homoserine lactone as the sole source of energy and nitrogen. The bacterium was classified as a strain of Variovorax paradoxus. The V. paradoxus isolate was capable of growth on all of the acyl-HSLs tested. The molar growth yields correlated with the length of the acyl group. HSL, a product of acyl-HSL metabolism, was used as a nitrogen source, but not as an energy source. Cleavage and partial mineralization of the HSL ring were demonstrated by using radiolabeled substrate. This study indicates that some strains of V. paradoxus degrade and grow on acyl-HSL signals as the sole energy and nitrogen sources. This study provides clues about the metabolic pathway of acyl-HSL degradation by V. paradoxus.
...
PMID:Metabolism of acyl-homoserine lactone quorum-sensing signals by Variovorax paradoxus. 1109 51

A common form of bacterial quorum sensing involves the production and release of acyl homoserine lactone (AHL) signal metabolites. The nitrogen-fixing symbiont Rhizobium leguminosarum reportedly produces at least six different AHLs, but little is known about the regulation of biosynthesis of these molecules. We used a radiolabeling protocol to quantify the relative amounts of AHLs synthesized over time by R. leguminosarum cells with and without the symbiosis plasmid pRL1JI. Cells containing pRL1JI were found to produce three predominant signals. In decreasing order of abundance, these were N-(3-oxo)octanoyl homoserine lactone [(3-O)C(8)HSL], N-octanoyl homoserine lactone, and N-hexanoyl homoserine lactone. Cells without pRL1JI produced only two major signals, N-(3-hydroxy-7-cis)tetradecanoyl homoserine lactone [(3-OH)C(14:1)HSL] and (3-O)C(8)HSL. Each AHL exhibited a distinct temporal pattern of synthesis, suggesting that each AHL is subject to unique regulatory mechanisms. While (3-O)C(8)HSL was produced in both cultures, the patterns of synthesis were different in cells with and without pRL1JI, possibly as a result of redundant gene functions that are present on both the chromosome and the symbiosis plasmid. None of the AHLs appeared to regulate its own biosynthesis, although exogenous (3-OH)C(14:1)HSL did activate synthesis of the three AHLs made by cells containing pRL1JI. These results indicate that the synthesis of multiple AHLs in R. leguminosarum is regulated by complex mechanisms that operate independently of quorum sensing itself but that (3-OH)C(14:1)HSL can supersede these controls in pRL1JI-containing cells. This work provides an important global perspective for AHL regulation that both complements and contrasts with the results of previous studies performed with isolated gene systems.
...
PMID:Multiple N-acyl homoserine lactone signals of Rhizobium leguminosarum are synthesized in a distinct temporal pattern. 1169 64

Rhizobium sp. strain NGR234 forms symbiotic, nitrogen-fixing nodules on a wide range of legumes via functions largely encoded by the plasmid pNGR234a. The pNGR234a sequence revealed a region encoding plasmid replication (rep) and conjugal transfer (tra) functions similar to those encoded by the rep and tra genes from the tumor-inducing (Ti) plasmids of Agrobacterium tumefaciens, including homologues of the Ti plasmid quorum-sensing regulators TraI, TraR, and TraM. In A. tumefaciens, TraI, a LuxI-type protein, catalyzes synthesis of the acylated homoserine lactone (acyl-HSL) N-3-oxo-octanoyl-L-homoserine lactone (3-oxo-C8-HSL). TraR binds 3-oxo-C8-HSL and activates expression of Ti plasmid tra and rep genes, increasing conjugation and copy number at high population densities. TraM prevents this activation under noninducing conditions. Although the pNGR234a TraR, TraI, and TraM appear to function similarly to their A. tumefaciens counterparts, the TraR and TraM orthologues are not cross-functional, and the quorum-sensing systems have differences. NGR234 TraI synthesizes an acyl-HSL likely to be 3-oxo-C8-HSL, but traI mutants and a pNGR234a-cured derivative produce low levels of a similar acyl-HSL and another, more hydrophobic signal molecule. TraR activates expression of several pNGR234a tra operons in response to 3-oxo-C8-HSL and is inhibited by TraM. However, one of the pNGR234a tra operons is not activated by TraR, and conjugal efficiency is not affected by TraR and 3-oxo-C8-HSL. The growth rate of NGR234 is significantly decreased by TraR and 3-oxo-C8-HSL through functions encoded elsewhere in the NGR234 genome.
...
PMID:Quorum sensing in Rhizobium sp. strain NGR234 regulates conjugal transfer (tra) gene expression and influences growth rate. 1253 56

Many Proteobacteria produce acyl-homoserine lactones (acyl-HSLs) and employ them as dedicated cell-to-cell signals in a process known as quorum sensing. Previously, Variovorax paradoxus VAI-C was shown to utilize diverse acyl-HSLs as sole sources of energy and nitrogen. We describe here the properties of a second isolate, Arthrobacter strain VAI-A, obtained from the same enrichment culture that yielded V. paradoxus VAI-C. Although strain VAI-A grew rapidly and exponentially on a number of substrates, it grew only slowly and aberrantly (i.e., linearly) in media amended with oxohexanoyl-HSL as the sole energy source. Increasing the culture pH markedly improved the growth rate in media containing this substrate but did not abolish the aberrant kinetics. The observed growth was remarkably similar to the known kinetics of the pH-influenced half-life of acyl-HSLs, which decay chemically to yield the corresponding acyl-homoserines. Strain VAI-A grew rapidly and exponentially when provided with an acyl-homoserine as the sole energy or nitrogen source. The isolate was also able to utilize HSL as a sole source of nitrogen but not as energy for growth. V. paradoxus, known to release HSL as a product of quorum signal degradation, was examined for the ability to support the growth of Arthrobacter strain VAI-A in defined cocultures. It did. Moreover, the acyl-HSL-dependent growth rate and yield of the coculture were dramatically superior to those of the monocultures. This suggested that the original coenrichment of these two organisms from the same soil sample was not coincidental and that consortia may play a role in quorum signal turnover and mineralization. The fact that Arthrobacter strain VAI-A utilizes the two known nitrogenous degradation products of acyl-HSLs, acyl-homoserine and HSL, begins to explain why none of the three compounds are known to accumulate in the environment.
...
PMID:Arthrobacter strain VAI-A utilizes acyl-homoserine lactone inactivation products and stimulates quorum signal biodegradation by Variovorax paradoxus. 1257 Oct 11

A novel chemically defined medium, named KG medium, supplemented with N-3-oxo-hexanoylhomoserine lactone (3-oxo-C6-HSL), an acylhomoserine lactone (AHL) used as signalling molecules in Gram-negative bacterial cell-to-cell communication, as the sole source of carbon and nitrogen, was designed and successfully used for the enrichment and isolation of AHL-degrading bacteria. A 3-oxo-C6-HSL-degrading bacterium, 13sw7, was isolated from sewage after six enrichment transfers in the 3-oxo-C6-HSL-containing KG medium. On the basis of the almost complete 16S ribosomal DNA sequence, isolate 13sw7 was clustered with unculturable beta-proteobacteria. This study indicates that the AHL-containing KG medium is effective in isolating AHL-degrading bacteria, including those previously considered unculturable, from environmental sources. To the best of our knowledge, this is the first documentation of the isolation of an AHL-degrading proteobacterium from sewage.
...
PMID:A novel medium for the isolation of N-acylhomoserine lactone-degrading bacteria. 1894 94

Acyl-homoserine lactone (acyl-HSL) quorum-sensing signaling is common to many Proteobacteria. Acyl-HSLs are synthesized by the LuxI family of synthases, and the signal response is mediated by members of the LuxR family of transcriptional regulators. Burkholderia thailandensis is a member of a closely related cluster of three species, including the animal pathogens Burkholderia mallei and Burkholderia pseudomallei. Members of this group have similar luxI and luxR homologs, and these genes contribute to B. pseudomallei and B. mallei virulence. B. thailandensis possesses three pairs of luxI-luxR homologs. One of these pairs, BtaI2-BtaR2, has been shown to produce and respond to 3OHC(10)-HSL and to control the synthesis of an antibiotic. By using a markerless-exhange method, we constructed an assortment of B. thailandensis quorum-sensing mutants, and we used these mutants to show that BtaI1 is responsible for C(8)-HSL production and BtaI3 is responsible for 3OHC(8)-HSL production. We also show that a strain incapable of acyl-HSL production is capable of growth on the same assortment of carbon and nitrogen sources as the wild type. Furthermore, this mutant shows no loss of virulence compared to the wild type in mice. However, the wild type self-aggregates in minimal medium, whereas the quorum-sensing mutant does not. The wild-type aggregation phenotype is recovered by addition of the BtaI1-R1 HSL signal C(8)-HSL. We propose that the key function of the BtaR1-BtaI1 quorum-sensing system is to cause cells to gather into aggregates once a sufficient population has been established.
...
PMID:Mutational analysis of Burkholderia thailandensis quorum sensing and self-aggregation. 1964 50

The symbiosis island ICEMlSym(R7A) of Mesorhizobium loti R7A is an integrative and conjugative element (ICE) that carries genes required for a nitrogen-fixing symbiosis with Lotus species. ICEMlSym(R7A) encodes homologues (TraR, TraI1 and TraI2) of proteins that regulate plasmid transfer by quorum sensing in rhizobia and agrobacteria. Introduction of traR cloned on a plasmid induced excision of ICEMlSym(R7A) in all cells, a 1000-fold increase in the production of 3-oxo-C6-homoserine lactone (3-oxo-C6-HSL) and a 40-fold increase in conjugative transfer. These effects were dependent on traI1 but not traI2. Induction of expression from the traI1 and traI2 promoters required the presence of plasmid-borne traR and either traI1 or 100 pM 3-oxo-C6-HSL, suggesting that traR expression or TraR activity is repressed in wild-type cells by a mechanism that can be overcome by additional copies of traR. The traI2 gene formed an operon with hypothetical genes msi172 and msi171 that were essential for ICEMlSym(R7A) excision and transfer. Our data suggest that derepressed TraR in conjunction with TraI1-synthesized 3-oxo-C6-HSL regulates excision and transfer of ICEMlSym(R7A) through expression of msi172 and msi171. Homologues of msi172 and msi171 were present on putative ICEs in several alpha-proteobacteria, indicating a conserved role in ICE excision and transfer.
...
PMID:A LuxRI-family regulatory system controls excision and transfer of the Mesorhizobium loti strain R7A symbiosis island by activating expression of two conserved hypothetical genes. 1968 58

The role of quorum sensing (QS) in the response of Pseudomonas aeruginosa to UVA radiation was investigated in the PAO1 strain and derivatives defective in the synthesis of the QS signals 3OC12-HSL (lasI strain), C4-HSL (rhlI strain) or both (lasI rhlI strain). Cell viability measurements demonstrated that the double mutant was significantly more sensitive to UVA than single mutants, which in turn showed reduced cell survival with regard to the PAO1 strain. Irradiation under nitrogen atmosphere and chemiluminescence measurements indicated the oxidative nature of the UVA-induced damage. The activity of the antioxidant enzymes catalase and superoxide dismutase was assayed in these strains before and after irradiation, and a strong correlation between catalase levels and UVA sensitivity was observed. When a sublethal UVA dose was applied to PAO1, a growth delay was observed and this mechanism depended on the rhl system. Moreover, low doses of UVA irradiation triplicated the level of C4-HSL in log PAO1 cells. It is concluded that QS is fundamental in the defense against the toxic effects of UVA in P. aeruginosa. The induction of the QS system by UVA independently of cell density could function as an adaptative strategy to withstand this hostile environmental condition.
...
PMID:Role of the quorum sensing mechanism in the response of Pseudomonas aeruginosa to lethal and sublethal UVA irradiation. 2086 92

Bacteria secrete small signal molecules into the environment that induce self and neighbour gene expression. This phenomenon, termed quorum sensing, allows cooperative behaviours that increase the fitness of the group. The best-studied signal molecules are the N-acylhomoserine lactones (AHLs), secreted by a growing number of bacterial species including important pathogen species such as Pseudomonas aeruginosa. These molecules have recently been proposed to have properties other than those of signalling, functioning as iron quelants or antibiotics. As the presence of an acylase capable of inactivating long-chain AHLs in Anabaena sp. PCC7120 could constitute a defence mechanism against these molecules, in this work we analyse the effects of different AHLs varying in length and substitutions on the growth and nitrogen metabolism of the cyanobacterium Anabaena sp. PCC7120. All the AHLs tested strongly inhibited nitrogen fixation. The inhibition seems to take place at post-transcriptional level, as no effect on heterocyst differentiation or on the expression of nitrogenase was observed. Moreover, N-(3-oxodecanoyl)-l-homoserine lactone (OC10-HSL) showed a specific cytotoxic effect on this cyanobacterium in the presence of a combined nitrogen source, but the mechanism involved seems to be different from that described so far for tetramic acid derivatives of oxo-substituted AHLs. These results suggest a variety of new unexpected activities for AHLs, at least on cyanobacterial populations.
...
PMID:Quorum sensing N-acylhomoserine lactone signals affect nitrogen fixation in the cyanobacterium Anabaena sp. PCC7120. 2120 19


1 2 3 4 Next >>

---