TheglcBlocus ofRhizobium leguminosarumVF39 encodes an arabinose-inducible malate synthase

2002 ◽  
Vol 48 (10) ◽  
pp. 922-932 ◽  
Author(s):  
Alejandro García-de los Santos ◽  
Alejandro Morales ◽  
Laura Baldomá ◽  
Scott R.D Clark ◽  
Susana Brom ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Plant Cell Wall ◽  
Glyoxylate Cycle ◽  
Malate Synthase ◽  
Mesorhizobium Loti ◽  
Malate Synthase G ◽  
Similar Genome Organization ◽  
The Glyoxylate Cycle

In the course of a study conducted to isolate genes upregulated by plant cell wall sugars, we identified an arabinose-inducible locus from a transcriptional fusion library of Rhizobium leguminosarum VF39, carrying random insertions of the lacZ transposon Tn5B22. Sequence analysis of the locus disrupted by the transposon revealed a high similarity to uncharacterized malate synthase G genes from Sinorhizobium meliloti, Agrobacterium tumefaciens, and Mesorhizobium loti. This enzyme catalyzes the condensation of glyoxylate and acetyl-CoA to yield malate and CoA and is thought to be a component of the glyoxylate cycle, which allows microorganisms to grow on two carbon compounds. Enzyme assays showed that a functional malate synthase is encoded in the glcB gene of R. leguminosarum and that its expression is induced by arabinose, glycolate, and glyoxylate. An Escherichia coli aceB glcB mutant, complemented with the R. leguminosarum PCR-amplified gene, recovered malate synthase activity. A very similar genome organization of the loci containing malate synthase and flanking genes was observed in R. leguminosarum, S. meliloti, and A. tumefaciens. Pea plants inoculated with the glcB mutant or the wild-type strain showed no significant differences in nitrogen fixation. This is the first report regarding the characterization of a mutant in one of the glyoxylate cycle enzymes in the rhizobia.Key words: Rhizobium, malate synthase, glyoxylate cycle, arabinose metabolism.

scholarly journals Binding Site Determinants for the LysR-Type Transcriptional Regulator PcaQ in the Legume Endosymbiont Sinorhizobium meliloti

2007 ◽  
Vol 190 (4) ◽  
pp. 1237-1246 ◽  
Author(s):  
Allyson M. MacLean ◽  
Michelle I. Anstey ◽  
Turlough M. Finan
Keyword(s):  
Binding Site ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Transcriptional Start Site ◽  
Mesorhizobium Loti ◽  
Equilibrium Dissociation ◽  
Dyad Symmetry

ABSTRACT LysR-type transcriptional regulators represent one of the largest groups of prokaryotic regulators described to date. In the gram-negative legume endosymbiont Sinorhizobium meliloti, enzymes involved in the protocatechuate branch of the β-ketoadipate pathway are encoded within the pcaDCHGB operon, which is subject to regulation by the LysR-type protein PcaQ. In this work, purified PcaQ was shown to bind strongly (equilibrium dissociation constant, 0.54 nM) to a region at positions −78 to −45 upstream of the pcaD transcriptional start site. Within this region, we defined a PcaQ binding site with dyad symmetry that is required for regulation of pcaD expression in vivo and for binding of PcaQ in vitro. We also demonstrated that PcaQ participates in negative autoregulation by monitoring expression of pcaQ via a transcriptional fusion to lacZ. Although pcaQ homologues are present in many α-proteobacteria, this work describes the first reported purification of this regulator, as well as characterization of its binding site, which is conserved in Agrobacterium tumefaciens, Rhizobium leguminosarum, Rhizobium etli, and Mesorhizobium loti.

Co-ordinate regulation of genes involved in storage lipid mobilization in Arabidopsis thaliana

2001 ◽  
Vol 29 (2) ◽  
pp. 283-286 ◽  
Author(s):  
E. L. Rylott ◽  
M. A. Hooks ◽  
I. A. Graham
Keyword(s):  
Arabidopsis Thaliana ◽  
Enzyme Activities ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Molecular Genetic ◽  
Regulation Of Gene Expression ◽  
Growth Period ◽  
Malate Synthase ◽  
The Glyoxylate Cycle

Molecular genetic approaches in the model plant Arabidopsis thaliana (ColO) are shedding new light on the role and control of the pathways associated with the mobilization of lipid reserves during oilseed germination and post-germinative growth. Numerous independent studies have reported on the expression of individual genes encoding enzymes from the three major pathways: β-oxidation, the glyoxylate cycle and gluconeogenesis. However, a single comprehensive study of representative genes and enzymes from the different pathways in a single plant species has not been done. Here we present results from Arabidopsis that demonstrate the co-ordinate regulation of gene expression and enzyme activities for the acyl-CoA oxidase- and 3-ketoacyl-CoA thiolasemediated steps of β-oxidation, the isocitrate lyase and malate synthase steps of the glyoxylate cycle and the phosphoenolpyruvate carboxykinase step of gluconeogenesis. The mRNA abundance and enzyme activities increase to a peak at stage 2, 48 h after the onset of seed germination, and decline thereafter either to undetectable levels (for malate synthase and isocitrate lyase) or low basal levels (for the genes of β-oxidation and gluconeogenesis). The co-ordinate induction of all these genes at the onset of germination raises the possibility that a global regulatory mechanism operates to induce the expression of genes associated with the mobilization of storage reserves during the heterotrophic growth period.

scholarly journals The Apparent Malate Synthase Activity of Rhodobacter sphaeroides Is Due to Two Paralogous Enzymes, (3S)-Malyl-Coenzyme A (CoA)/β-Methylmalyl-CoA Lyase and (3S)- Malyl-CoA Thioesterase

2010 ◽  
Vol 192 (5) ◽  
pp. 1249-1258 ◽  
Author(s):  
Tobias J. Erb ◽  
Lena Frerichs-Revermann ◽  
Georg Fuchs ◽  
Birgit E. Alber
Keyword(s):  
Rhodobacter Sphaeroides ◽  
Coenzyme A ◽  
Glyoxylate Cycle ◽  
Condensation Reaction ◽  
Malate Synthase ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Claisen Condensation ◽  
Enzyme Functions ◽  
The Glyoxylate Cycle

ABSTRACT Assimilation of acetyl coenzyme A (acetyl-CoA) is an essential process in many bacteria that proceeds via the glyoxylate cycle or the ethylmalonyl-CoA pathway. In both assimilation strategies, one of the final products is malate that is formed by the condensation of acetyl-CoA with glyoxylate. In the glyoxylate cycle this reaction is catalyzed by malate synthase, whereas in the ethylmalonyl-CoA pathway the reaction is separated into two proteins: malyl-CoA lyase, a well-known enzyme catalyzing the Claisen condensation of acetyl-CoA with glyoxylate and yielding malyl-CoA, and an unidentified malyl-CoA thioesterase that hydrolyzes malyl-CoA into malate and CoA. In this study the roles of Mcl1 and Mcl2, two malyl-CoA lyase homologs in Rhodobacter sphaeroides, were investigated by gene inactivation and biochemical studies. Mcl1 is a true (3S)-malyl-CoA lyase operating in the ethylmalonyl-CoA pathway. Notably, Mcl1 is a promiscuous enzyme and catalyzes not only the condensation of acetyl-CoA and glyoxylate but also the cleavage of β-methylmalyl-CoA into glyoxylate and propionyl-CoA during acetyl-CoA assimilation. In contrast, Mcl2 was shown to be the sought (3S)-malyl-CoA thioesterase in the ethylmalonyl-CoA pathway, which specifically hydrolyzes (3S)-malyl-CoA but does not use β-methylmalyl-CoA or catalyze a lyase or condensation reaction. The identification of Mcl2 as thioesterase extends the enzyme functions of malyl-CoA lyase homologs that have been known only as “Claisen condensation” enzymes so far. Mcl1 and Mcl2 are both related to malate synthase, an enzyme which catalyzes both a Claisen condensation and thioester hydrolysis reaction.

The fine structure and selected histochemistry of ungerminated basidiospores of Agrocybe acericola

1996 ◽  
Vol 74 (5) ◽  
pp. 780-787 ◽  
Author(s):  
Donald G. Ruch ◽  
Kiki Nurtjahja
Keyword(s):  
Fine Structure ◽  
Acid Phosphatase ◽  
Glyoxylate Cycle ◽  
Outer Wall ◽  
Spore Wall ◽  
Malate Synthase ◽  
Marker Enzyme ◽  
Wall Ultrastructure ◽  
Membrane Bound ◽  
The Glyoxylate Cycle

The basidiospore wall of Agrocybe acericola is composed of two distinct layers that are continuous around the spores. At the germ pore, the outer wall is very thin and the inner wall becomes thicker. The plasma membrane is appressed to the inner wall and lacks distinct invaginations. The protoplasm is densely packed with ribosomes. Spores contain very little lipid distributed at each end. Mitochondria are well defined and distributed throughout the cytoplasm. Spores are binucleate, with the two nuclei lying on a line nearly perpendicular to the long axis of the cell. Various sizes of single membrane-bound vacuoles are widely distributed in the cytoplasm. These vacuoles were shown to contain acid phosphatase, indicating lysosomal activity. Microbody-like organelles are observed, which are probably glyoxysomes, since assays of malate synthase, a marker enzyme of the glyoxylate cycle, are positive. Keywords: Agrocybe, spore wall ultrastructure, basidiospore ultrastructure, glyoxylate cycle, malate synthase, acid phosphatase.

The malate synthase of Paracoccidioides brasiliensis Pb01 is required in the glyoxylate cycle and in the allantoin degradation pathway

2009 ◽  
pp. 1-12
Author(s):  
Patricia Fernanda Zambuzzi-Carvalho ◽  
Aline Helena Da Silva Cruz ◽  
Ludier Kesser Santos-Silva ◽  
Alfredo Miranda Goes ◽  
Celia Maria De Almeida Soares ◽  
...  
Keyword(s):  
Paracoccidioides Brasiliensis ◽  
Glyoxylate Cycle ◽  
Degradation Pathway ◽  
Malate Synthase ◽  
The Glyoxylate Cycle

Pathways for phosphatidylcholine biosynthesis in bacteria

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3461-3471 ◽  
Author(s):  
Fernando Martínez-Morales ◽  
Max Schobert ◽  
Isabel M. López-Lara ◽  
Otto Geiger
Keyword(s):  
Borrelia Burgdorferi ◽  
Legionella Pneumophila ◽  
Bradyrhizobium Japonicum ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Brucella Melitensis ◽  
Membrane Lipid ◽  
Mesorhizobium Loti ◽  
Methylation Pathway ◽  
Phosphatidylcholine Biosynthesis

Phosphatidylcholine (PC) is the major membrane-forming phospholipid in eukaryotes with important structural and signalling functions. Although many prokaryotes lack PC, it can be found in significant amounts in membranes of rather diverse bacteria. Two pathways for PC biosynthesis are known in bacteria, the methylation pathway and the phosphatidylcholine synthase (PCS) pathway. In the methylation pathway, phosphatidylethanolamine is methylated three times to yield PC, in reactions catalysed by one or several phospholipid N-methyltransferases (PMTs). In the PCS pathway, choline is condensed directly with CDP-diacylglyceride to form PC in a reaction catalysed by PCS. Using cell-free extracts, it was demonstrated that Sinorhizobium meliloti, Agrobacterium tumefaciens, Rhizobium leguminosarum, Bradyrhizobium japonicum, Mesorhizobium loti and Legionella pneumophila have both PMT and PCS activities. In addition, Rhodobacter sphaeroides has PMT activity and Brucella melitensis, Pseudomonas aeruginosa and Borrelia burgdorferi have PCS activities. Genes from M. loti and L. pneumophila encoding a Pmt or a Pcs activity and the genes from P. aeruginosa and Borrelia burgdorferi responsible for Pcs activity have been identified. Based on these functional assignments and on genomic data, one might predict that if bacteria contain PC as a membrane lipid, they usually possess both bacterial pathways for PC biosynthesis. However, important pathogens such as Brucella melitensis, P. aeruginosa and Borrelia burgdorferi seem to be exceptional as they possess only the PCS pathway for PC formation.

STUDIES ON RUMEN COLIFORM ORGANISMS: II. UTILIZATION OF ACETATE BY ESCHERICHIA COLI 64 ISOLATED FROM THE RUMEN FLUID OF A COW FED ALFALFA HAY

1967 ◽  
Vol 47 (3) ◽  
pp. 199-209 ◽  
Author(s):  
C. R. Krishnamurti ◽  
L. W. McElroy
Keyword(s):  
Sodium Acetate ◽  
Isocitrate Lyase ◽  
Protein Hydrolysate ◽  
Rumen Fluid ◽  
Glyoxylate Cycle ◽  
Malate Synthase ◽  
E Coli ◽  
Spectrophotometric Methods ◽  
Acetate Medium ◽  
The Glyoxylate Cycle

When cells of E. coli 64 were harvested in their exponential phase of growth in an acetate medium and incubated aerobically with sodium acetate-2-C14, about 33% of the label appeared in CO2 after 1 hr. Of the radioactivity in the cells, 72% was recovered in the protein hydrolysate, 8% in the nucleic acid, 6% in the lipid and 14% in the ethanol-soluble fractions. The radioactivity in the protein hydrolysate of cells incubated with sodium acetate-2-C14 was approximately 20 times that in the hydrolysate of cells incubated with C14O2 as the carbon source. By spectrophotometric methods, it was demonstrated that cell-free extracts of cells grown on acetate contained acetate kinase and phosphate acetyltransferase, plus, as demonstrated by spectrophotometric and isotopic methods, isocitrate lyase and malate synthase which are characteristic of the glyoxylate cycle. The enzymes of the glyoxylate cycle could not be demonstrated in cell-free extracts of E. coli 64 grown on glucose under either aerobic or anaerobic conditions. Possible functions that E. coli 64 may have in the maintenance of anaerobiosis in the rumen and utilization of acetate through the glyoxylate pathway are discussed.

scholarly journals The malate synthase ofParacoccidioides brasiliensis Pb01 is required in the glyoxylate cycle and in the allantoin degradation pathway

2009 ◽  
Vol 47 (7) ◽  
pp. 734-744 ◽  
Author(s):  
Patrícia Fernanda Zambuzzi-Carvalho ◽  
Aline Helena Da Silva Cruz ◽  
Ludier Kesser Santos-Silva ◽  
Alfredo Miranda Goes ◽  
Célia Maria De Almeida Soares ◽  
...  
Keyword(s):  
Glyoxylate Cycle ◽  
Degradation Pathway ◽  
Malate Synthase ◽  
The Glyoxylate Cycle

scholarly journals Nickel Availability and hupSL Activation by Heterologous Regulators Limit Symbiotic Expression of theRhizobium leguminosarum bv. Viciae Hydrogenase System in Hup− Rhizobia

2000 ◽  
Vol 66 (3) ◽  
pp. 937-942 ◽  
Author(s):  
Belén Brito ◽  
Jorge Monza ◽  
Juan Imperial ◽  
Tomás Ruiz-Argüeso ◽  
Jose Manuel Palacios
Keyword(s):  
Transcriptional Activation ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Transcriptional Regulator ◽  
Hydrogen Uptake ◽  
Hydrogenase Activity ◽  
Structural Genes ◽  
Mesorhizobium Loti ◽  
Genes Expression ◽  
Relevant Factors

ABSTRACT A limited number of Rhizobium andBradyrhizobium strains possess a hydrogen uptake (Hup) system that recycles the hydrogen released from the nitrogen fixation process in legume nodules. To extend this ability to rhizobia that nodulate agronomically important crops, we investigated factors that affect the expression of a cosmid-borne Hup system from Rhizobium leguminosarum bv. viciae UPM791 in R. leguminosarumbv. viciae, Rhizobium etli, Mesorhizobium loti, and Sinorhizobium meliloti Hup− strains. After cosmid pAL618 carrying the entire hup system of strain UPM791 was introduced, all recipient strains acquired the ability to oxidize H2 in symbioses with their hosts, although the levels of hydrogenase activity were found to be strain and species dependent. The levels of hydrogenase activity were correlated with the levels of nickel-dependent processing of the hydrogenase structural polypeptides and with transcription of structural genes. Expression of the NifA-dependent hupSL promoter varied depending on the genetic background, while the hyp operon, which is controlled by the FnrN transcriptional regulator, was expressed at similar levels in all recipient strains. With the exception of theR. etli-bean symbiosis, the availability of nickel to bacteroids strongly affected hydrogenase processing and activity in the systems tested. Our results indicate that efficient transcriptional activation by heterologous regulators and processing of the hydrogenase as a function of the availability of nickel to the bacteroid are relevant factors that affect hydrogenase expression in heterologous rhizobia.

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