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

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Query: EC:1.1.1.37 (malate dehydrogenase)
4,591 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Newborns are less able to concentrate urine than adults are. With development of the concentrating system and a hypertonic medullary interstitium, there is a need to generate intracellular osmolytes such as sorbitol, which is produced in a reaction catalyzed by the enzyme aldose reductase. We sought to discriminate between two possible mechanisms of aldose reductase induction during development: (a) a response to an osmotic stimulus generated by the concentrating mechanism; or (b) part of the genetic program for development of the kidney. We measured the change in aldose reductase mRNA and activity in terminal inner medullary collecting ducts (IMCDs) microdissected from Sprague-Dawley rats during the first month of life. Aldose reductase mRNA was assayed by Northern analysis of total RNA from inner medulla and by detection of the reverse transcription-polymerase chain reaction (RT-PCR) product obtained from single IMCDs using aldose reductase-specific primers. Aldose reductase activity was measured in IMCDs taken from the same rats using a fluorescent microassay. Newborn rat IMCDs had minimal aldose reductase mRNA or activity, however mRNA was readily detected in IMCDs from rats older than 3 d of age, with peak expression occurring at 1-3 wk of age before decreasing to adult levels. In contrast, the mRNA level for a housekeeping metabolic enzyme, malate dehydrogenase, did not change during maturation. Aldose reductase enzyme activity was readily detectable by 6 d of age, peaked at 20 d, then decreased to adult levels. Urine osmolality remained < 600 mosmol/kg until 16 d, then increased to > 1,100 mosmol/kg after 20 d. Thus, aldose reductase mRNA and activity increased before urinary osmolality reached 870 mosmol/kg. Because urine osmolality may not be indicative of inner medullary osmolality and because mother's milk may provide excessive free water to the pups under 3 wk of age, half of the animals in several litters were separated from their mothers for 1 d and inner medullary osmolality, in addition to urine osmolality, was measured by vapor pressure osmometry, while aldose reductase mRNA was assessed densitometrically in IMCDs after RT-PCR. Although fluid restriction resulted in a near doubling of urine osmolality and a tendency towards increased aldose reductase mRNA, there was no consistently significant increase in aldose reductase mRNA or inner medullary osmolality during the first 13 d of life compared to the suckling animals. On the other hand, 2-3-wk-old rats showed significant increases in aldose reductase mRNA, accompanied by increases in inner medullary osmolality, after fluid restriction. Thus, the dissociation between the increases in aldose reductase expression and inner medullary hyperosmolality indicates that the maturational induction of the aldose reductase gene is not a consequence of osmotic stimulation, but rather, part of the developmental program of the kidney.
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PMID:Maturation of aldose reductase expression in the neonatal rat inner medulla. 140 Oct 64

Nucleotide sequences of the mdh gene encoding the metabolic enzyme malate dehydrogenase (MDH) were determined for 44 strains representing the major lineages of Escherichia coli and the eight subspecies of Salmonella enterica. Sequence diversity was four times greater in S. enterica than in E. coli, and in both species the rate of amino acid substitution was lower in the NAD(+)-binding domain than in the catalytic domain. Divergence of the mdh genes of the two species apparently has not involved excess nonsynonymous substitutions resulting from the fixation of adaptive amino acid mutations. Allozyme analysis detected 57% of the distinctive amino acid sequences. Statistical tests of the distribution of polymorphic synonymous nucleotide sites identified four possible intragenic recombination events, one involving a single allele of E. coli and three involving alleles of the three subspecies of S. enterica. But recombination at mdh has not occurred with sufficient frequency to obscure the phylogenetic relationships among strains indicated by multilocus enzyme electrophoresis, total DNA hybridization, and sequence analysis of the gapA and putP genes. These findings provide further evidence that the effective (realized) rates of horizontal transfer and recombination for metabolic enzyme and other housekeeping genes are generally low in these species, in contrast to those for loci encoding or mediating the structure of cell-surface and other macromolecules for which recombinants may be subject to strong balancing, directional, or diversifying selection.
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PMID:Molecular genetic basis of allelic polymorphism in malate dehydrogenase (mdh) in natural populations of Escherichia coli and Salmonella enterica. 810 2

Carbonic anhydrase (CA) facilitates renal bicarbonate reabsorption and acid excretion. Cytosolic CA II catalyzes the buffering of intracellular hydroxyl ions by CO2, whereas membrane-bound CA IV catalyzes the dehydration of carbonic acid generated from the secretion of protons. Although CA II and IV are expressed in rabbit kidney, it is not entirely clear which segments express which isoforms. It was the purpose of this study to characterize the expression of CA II and CA IV mRNAs by specific segments of the nephron using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and to determine the effect of chronic metabolic acidosis on CA expression by those segments. Individual nephron segments (usually 1-2 mm) were isolated by microdissection and subjected to RT-PCR. Amplification was performed simultaneously for CA IV, CA II, and malate dehydrogenase (MDH), a housekeeping gene. The intensities of the PCR products were quantitated by densitometry. CA IV mRNA was expressed by S1 and S2 proximal tubules and by outer medullary collecting duct from inner stripe (OMCDi) and outer stripe and initial inner medullary collecting duct (IMCDi). CA II mRNA was expressed by S1, S2, and S3 proximal tubules, thin descending limb, connecting segment (CNT), and all collecting duct segments. Acid loading induced CA IV mRNA expression in S1 and S2 proximal tubules and in OMCDi and IMCDi. CA II mRNA was induced by acidosis in all three proximal segments and nearly all distal segments beginning with CNT. No upregulation of MDH mRNA expression occurred. These adaptive increases in CA II and IV mRNAs are potentially important in the kidney's adaptation to chronic metabolic acidosis.
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PMID:Carbonic anhydrase II and IV mRNA in rabbit nephron segments: stimulation during metabolic acidosis. 948 20

To study the adjustments made to the tricarboxylic acid cycle during symbiosis of nitrogen-fixing rhizobia with their host legumes, we have characterized the genes encoding the alpha-ketoglutarate dehydrogenase enzyme complex in Bradyrhizobium japonicum. The genes were arranged in the order sucA-sucB-scdA-lpdA, where scdArepresents a short-chain dehydrogenase gene (GenBank accession No. AY049030). All four genes appeared to be co-transcribed, an arrangement that is so far unique to B. japonicum. The mdh gene, encoding malate dehydrogenase, was located upstream of the sucA operon, and its primary transcript appeared to be monocistronic. Primer extension indicated that the sucA operon and mdh were transcribed from typical housekeeping promoters.
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PMID:Comparative analysis of the Bradyrhizobium japonicum sucA region. 1289 32

We investigated the diversity of the chromosomal class A beta-lactamase gene in Klebsiella pneumoniae in order to study the evolution of the gene. A 789-bp portion was sequenced in a panel of 28 strains, representative of three phylogenetic groups, KpI, KpII, and KpIII, recently identified in K. pneumoniae and of different chromosomal beta-lactamase variants previously identified. Three groups of sequences were found, two of them corresponding to the families SHV (pI 7.6) and LEN (pI 7.1), respectively, and one, more heterogeneous, corresponding to a new family that we named OKP (for other K. pneumoniae beta-lactamase). Levels of susceptibility to ampicillin, cefuroxime, cefotaxime, ceftazidime, and aztreonam and inhibition by clavulanic acid were similar in the three groups. One new SHV variant, seven new LEN variants, and four OKP variants were identified. The OKP variants formed two subgroups based on nucleotide sequences, one with pIs of 7.8 and 8.1 and the other with pIs of 6.5 and 7.0. The nucleotide sequences of the housekeeping genes gyrA, coding for subunit A of gyrase, and mdh, coding for malate dehydrogenase, were also determined. Phylogenetic analysis of the three genes studied revealed parallel evolution, with the SHV, OKP, and LEN beta-lactamase families corresponding to the phylogenetic groups KpI, KpII, and KpIII, respectively. This correspondence was fully confirmed for 34 additional strains in PCR assays specific for the three beta-lactamase families. We estimated the time since divergence of the phylogenetic groups KpI and KpIII at between 6 and 28 million years, confirming the ancient presence of the beta-lactamase gene in the genome of K. pneumoniae.
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PMID:Diversity and evolution of the class A chromosomal beta-lactamase gene in Klebsiella pneumoniae. 1521 87

Vibrio cholerae, the causative agent of cholera, is a natural inhabitant of the aquatic ecosystem. We examined a unique collection of V. cholerae clinical and environmental isolates of widespread geographic distribution recovered over a 60-year period to determine their evolutionary genetic relationships based on analysis of two housekeeping genes, malate dehydrogenase (mdh) and a chaperonin (groEL). In addition, the phylogenetic distribution of 12 regions associated with virulence was determined. Comparative sequence analysis of mdh revealed that all V. cholerae O1 and O139 serogroup isolates belonged to the same clonal lineage. Single-strand conformational polymorphism (SSCP) analysis of these O1 and O139 strains at groEL confirmed the presence of an epidemic clonal complex. Of the 12 virulence regions examined, only three regions, Vibrio seventh pandemic island 1 (VSP-I), VSP-II, and RS1, were absent from all classical V. cholerae isolates. Most V. cholerae El Tor biotype and O139 serogroup isolates examined encoded all 12 virulence regions assayed. Outside of V. cholerae O1/O139 serogroup isolates, only one strain, VO7, contained VSP-I. Two V. cholerae El Tor isolates, GP155 and 2164-78, lacked both VSP-I and VSP-II, and one El Tor isolate, GP43, lacked VSP-II. Five non-O1/non-O139 serogroup isolates had an mdh sequence identical to that of the epidemic O1 and O139 strains. These isolates, similar to classical strains, lack both VSP-I and VSP-II. Four of the 12 virulence regions examined were found to be present in all isolates: hlyA, pilE, MSHA and RTX. Among non-O1/non-O139 isolates, however, the occurrence of the additional eight regions was considerably lower. The evolutionary relationships and multilocus virulence gene profiles of V. cholerae natural isolates indicate that consecutive pandemic strains arose from a common O1 serogroup progenitor through the successive acquisition of new virulence regions.
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PMID:Evolutionary genetic analysis of the emergence of epidemic Vibrio cholerae isolates on the basis of comparative nucleotide sequence analysis and multilocus virulence gene profiles. 1547 25

Pseudomonas aeruginosa is a gram-negative rod that is ubiquitous in nature. P. aeruginosa is also the quintessential opportunistic pathogen, causing a wide variety of infections in compromised hosts. In cystic fibrosis patients, P. aeruginosa is the leading cause of death. In this study, the evolutionary genetic relationships among 17 P. aeruginosa isolates were examined by comparative sequence analysis of the housekeeping gene encoding malate dehydrogenase and the chaperone groEL. The P. aeruginosa isolates examined included the sequenced strain PAO1, 11 strains recovered from cystic fibrosis patients in Ireland, 4 environmental isolates recovered from a hospital environment, and 1 isolate recovered from a plant rhizosphere. Phylogenetically, clinical and environmental isolates clustered together with one another on the mdh gene tree. At the groEL locus, among the 17 isolates examined, only two polymorphic sites were observed, highlighting the close genetic relationship between isolates from these different environments. Phenotypic analysis of 12 traits among our isolates, however, found that only clinical isolates produced phenazines and elastase. Furthermore, molecular analysis of the distribution of 15 regions associated with virulence showed that two of the environmental isolates examined lacked the majority of regions. Among the clinical isolates examined, the 15 virulence regions were variably present. The distribution of two prophages (Bacto1, Pf1) was also determined, with most isolates encoding both these regions. Of the four genomic islands (the flagellum island and PAGI-1, -2, and -3) examined, only two isolates contained the flagellum island, and PAGI-1, -2, and -3 were absent from all isolates tested. Our data demonstrate the significant role horizontal gene transfer and recombination, together with gene loss, play in the evolution of this important human pathogen.
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PMID:Genome diversity of Pseudomonas aeruginosa isolates from cystic fibrosis patients and the hospital environment. 1558 13

Vibrio cholerae is a Gram-negative rod that inhabits the aquatic environment and is the aetiological agent of cholera, a disease that is endemic in much of Southern Asia. The 57.3 kb Vibrio pathogenicity island-2 (VPI-2) is confined predominantly to toxigenic V. cholerae O1 and O139 serogroup isolates and encodes 52 ORFs (VC1758 to VC1809), which include homologues of an integrase (VC1758), a restriction modification system, a sialic acid metabolism gene cluster (VC1773-VC1783), a neuraminidase (VC1784) and a gene cluster that shows homology to Mu phage. In this study, a 14.1 kb region of VPI-2 comprising ORFs VC1773 to VC1787 was identified by PCR and Southern blot analyses in all 17 Vibrio mimicus isolates examined. The VPI-2 region in V. mimicus was inserted adjacent to a serine tRNA similar to VPI-2 in V. cholerae. In 11 of the 17 V. mimicus isolates examined, an additional 5.3 kb region encoding VC1758 and VC1804 to VC1809 was present adjacent to VC1787. The evolutionary history of VPI-2 was reconstructed by comparative analysis of the nanH (VC1784) gene tree with the species gene tree, deduced from the housekeeping gene malate dehydrogenase (mdh), among V. cholerae and V. mimicus isolates. Both gene trees showed an overall congruence; on both gene trees V. cholerae O1 and O139 serogroup isolates clustered together, whereas non-O1/non-O139 serogroup isolates formed separate divergent branches with similar clustering of strains within the branches. One exception was noted: on the mdh gene tree, V. mimicus sequences formed a distinct divergent lineage from V. cholerae sequences; however, on the nanH gene tree, V. mimicus clustered with V. cholerae non-O1/non-O139 isolates, suggesting horizontal transfer of this region between these species.
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PMID:Molecular evolution of Vibrio pathogenicity island-2 (VPI-2): mosaic structure among Vibrio cholerae and Vibrio mimicus natural isolates. 1563 48

High-throughput MS/MS was used to identify proteins secreted by Fusarium graminearum (Gibberella zeae) during growth on 13 media in vitro and in planta during infection of wheat heads. In vitro secreted proteins were collected from the culture filtrates, and in planta proteins were collected by vacuum infiltration. A total of 289 proteins (229 in vitro and 120 in planta) were identified with high statistical confidence. Forty-nine of the in planta proteins were not found in any of the in vitro conditions. The majority (91-100%) of the in vitro proteins had predicted signal peptides, but only 56% of the in planta proteins. At least 13 of the nonsecreted proteins found only in planta were single-copy housekeeping enzymes, including enolase, triose phosphate isomerase, phosphoglucomutase, calmodulin, aconitase, and malate dehydrogenase. The presence of these proteins in the in planta but not in vitro secretome might indicate that significant fungal lysis occurs during pathogenesis. On the other hand, several of the proteins lacking signal peptides that were found in planta have been reported to be potent immunogens secreted by animal pathogenic fungi, and therefore could be important in the interaction between F. graminearum and its host plants.
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PMID:Comparative proteomics of extracellular proteins in vitro and in planta from the pathogenic fungus Fusarium graminearum. 1767 64

Interspecific comparative studies require that expression data be comparable among species, and when species with different levels of ploidy are contemplated the relative expression per cell should be obtained for accurate comparisons to be made. Quantitative reverse-transcription-PCR is the most popular and sensitive technique for the detection and quantification of mRNA in gene expression analysis. In recent years it has become clear that the choice of reference genes for the normalization of expression data is very important. Several studies have shown that the expression of the traditional housekeeping genes varies under certain situations; their use as reference genes in quantitative PCR assays can therefore lead to errors when interpreting the relative expression of target genes. Normalizing with respect to endogenous genes showing a constant level of expression per cell across species, however, provides an easy way of obtaining comparable expression data for other genes in those species. In this work, the validity of several candidate genes was examined across four diploid and polyploid species of the genera Triticum and Aegilops. Candidate reference genes were chosen among the traditional housekeeping genes used in quantitative PCR analysis, as well as others found to have stable levels of expression under different conditions in other studies. After the analyses, candidate genes were gathered into two groups according to the different levels of expression per cell seen in polyploid species. For the four species studied, two genes suitable for normalization procedures in interspecific studies were identified: cell division control protein and malate dehydrogenase. Both showed a constant number of transcripts per cell, independent of the level of ploidy.
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PMID:Comparative analysis of gene expression among species of different ploidy. 2498 81


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