Characterization of the Rhizobium leguminosarum genes nodLMN involved in efficient host‐specific nodulation

Surin, Prayoon; Downie, J. Allan

doi:10.1111/j.1365-2958.1988.tb00019.x

Cited by 105 publications

(87 citation statements)

References 51 publications

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“…viciae, mutations in nodM were reported to have no or only slight effects on nodulation, again depending on the plant host (32). For R leguminosarum bv.…”

Section: Discussionmentioning

confidence: 99%

“…The nodulation gene products are involved in producing signal molecules, the Nod factors, which elicit curling and deformation of the root hairs and meristematic cell division, leading to nodule formation (12). Using R meliloti strains overproducing the Nod factors, certain plant hosts (1,32), while in other hosts, nodM was required for efficient nodulation (1). Moreover, in R. leguminosarum bv.…”

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confidence: 99%

“…Downie [32]) in two steps. First, the 2.5-kb Sail fragment was cloned in pACYC184 (5), which was then linearized with BamHI and cloned into the BglII site of pRK290 (6).…”

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Rhizobium nodM and nodN genes are common nod genes: nodM encodes functions for efficiency of nod signal production and bacteroid maturation

et al. 1992

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Earlier, we showed that Rhizobium meliloi nod&f codes for glucosamine synthase and that nodM and nodN mutants produce strongly reduced root hair deformation activity and display delayed nodulation of Medicago sativa (Baev et al., Mol. Gen. Genet. 228:113-124, 1991). Here, we demonstrate that nodPf and nodN genes from Rhizobium leguminosarum biovar viciae restore the root hair deformation activity of exudates of the corresponding R. meliloti mutant strains. Partial restoration of the nodulation phenotypes of these two strains was also observed. In nodulation assays, galactosamine and N-acetylglucosamine could substitute for glucosamine in the suppression of the R. melilot nodM mutation, although N-acetylglucosamine was less efficient. We observed that in nodules induced by nodM mutants, the bacteroids did not show complete development or were deteriorated, resulting in decreased nitrogen fixation and, consequently, lower dry weights of the plants. This mutant phenotype could also be suppressed by exogenously supplied glucosamine, N-acetylglucosamine, and galactosamine and to a lesser extent by glucosamine-6-phosphate, indicating that the nodAf mutant bacteroids are limited for glucosamine. In addition, by using derivatives of the wild type and a nod&t mutant in which the nod genes are expressed at a high constitutive level, it was shown that the nodM mutant produces significantly fewer Nod factors than the wild-type strain but that their chemical structures are unchanged. However, the relative amounts of analogs of the cognate Nod signals were elevated, and this may explain the observed host range effects of the nodM mutation. Our data indicate that both the nod&f and nodN genes of the two species have common functions and confirm that NodM is a glucosamine synthase with the biochemical role of providing sufficient amounts of the sugar moiety for the synthesis of the glucosamine oligosaccharide signal molecules.Rhizobia are capable of establishing symbiotic associations with their legume hosts. During this process, the bacteria undergo rapid developmental changes in order to make the transition from a soil environment through the root surface environment to a new ecological niche inside the plant host cells. The partnership between a given plant host and its microsymbiont is highly specific; most leguminous plants can be nodulated by a more or less limited number of Rhizobium species. For example, Rhizobium meliloti nodulates species of the genera Medicago, Meliotus, and Trigonella (11).Numerous bacterial and plant genes are expressed specifically during nodule development (19 Lerouge and coworkers (17) identified a major alfalfa-specific signal molecule as an acylated and sulfated glucosamine tetrasaccharide. Using a similar approach, we showed that R meliloti produces a family of biologically active Nod signal molecules (26). Host-specific signal molecules secreted by Rhizobium leguminosarum have also been identified (30).In different rhizobia, common and host-specific nod genes have been identified (12). The b...

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“…viciae, mutations in nodM were reported to have no or only slight effects on nodulation, again depending on the plant host (32). For R leguminosarum bv.…”

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Rhizobium nodM and nodN genes are common nod genes: nodM encodes functions for efficiency of nod signal production and bacteroid maturation

et al. 1992

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“…First, a structural domain, which is composed of parallel ␤-strands and called a left-handed parallel ␤-helix (47), appears to be well conserved in the amoebic SATs at the primary sequence level. This structure has been found in various acetyl-and acyltransferases, including UDP-N-acetylglucosamine 3-O-acyltransferase (47), chloramphenicol acetyltransferase (48), thiogalactoside acetyltransferase (49), and Rhizobium nodulation protein NodL (50). Second, the amoebic SATs contained a unique insertion between the coil regions 2 and 3.…”

Section: Cloning Of Ehsat Andmentioning

confidence: 99%

Characterization of the Gene Encoding Serine Acetyltransferase, a Regulated Enzyme of Cysteine Biosynthesis from the Protist ParasitesEntamoeba histolyticaand Entamoeba dispar

Nozaki

Asai

Sánchez

et al. 1999

Journal of Biological Chemistry

120

113

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The enteric protist parasites Entamoeba histolytica and Entamoeba dispar possess a cysteine biosynthetic pathway, unlike their mammalian host, and are capable of de novo production of L-cysteine. We cloned and characterized cDNAs that encode the regulated enzyme serine acetyltransferase (SAT) in this pathway from these amoebae by genetic complementation of a cysteine-auxotrophic Escherichia coli strain with the amoebic cDNA libraries. The deduced amino acid sequences of the amoebic SATs exhibited, within the most conserved region, 36 -52% identities with the bacterial and plant SATs. The amoebic SATs contain a unique insertion of eight amino acids, also found in the corresponding region of a plasmid-encoded SAT from Synechococcus sp., which showed the highest overall identities to the amoebic SATs. Phylogenetic reconstruction also revealed a close kinship of the amoebic SATs with cyanobacterial SATs. Biochemical characterization of the recombinant E. histolytica SAT revealed several enzymatic features that distinguished the amoebic enzyme from the bacterial and plant enzymes: 1) inhibition by L-cysteine in a competitive manner with L-serine; 2) inhibition by Lcystine; and 3) no association with cysteine synthase. Genetically engineered amoeba strains that overproduced cysteine synthase and SAT were created. The cysteine synthase-overproducing amoebae had a higher level of cysteine synthase activity and total thiol content and revealed increased resistance to hydrogen peroxide. These results indicate that the cysteine biosynthetic pathway plays an important role in antioxidative defense of these enteric parasites.The cysteine biosynthetic pathway plays an important role in incorporation of inorganic sulfur into organic compounds. In bacteria and plants, L-cysteine is the precursor of most sulfurcontaining metabolites including methionine and glutathione. Extracellular sulfate is first imported by specific transporters. Intracellular sulfate is then activated by ATP sulfurylase and adenosine-5Ј-phosphosulfate kinase to form adenosine-5Ј-phosphosulfate and 3Ј-phosphoadenosine 5Ј-phosphosulfate, respectively. These activated sulfates are further reduced to sulfide. Sulfide then reacts with O-acetylserine, which is produced from serine and acetyl-CoA by serine acetyltransferase (SAT, 1 EC 2.3.1.30). This final reaction forming L-cysteine, by transfer of the alanyl moiety of O-acetylserine to sulfide, is catalyzed by L-cysteine synthase (CS; O-acetyl-L-serine (thiol)-lyase, EC 4.2.99.8). In contrast to bacteria and plants, animals are presumed to lack the sulfur assimilation pathway and thus require exogenous methionine as a sulfur source. Biochemical studies using purified (1-4) and recombinant enzymes (5), as well as a genetic approach using a yeast two-hybrid system, revealed that CS and SAT form a heteromeric complex. SAT activity and O-acetylserine availability are the major regulatory factors in the control of the L-cysteine production in plants (6, 7). Cytosolic isoforms of the SAT from Citrullus vulgaris and A...

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“…The carboxyl half of the Tn2424 cat shows significant similarity to three proteins: the thiogalactoside acetyltransferase LacA of E. coli (15), the serine acetyltransferase CysE of E. coli (10), and a putative acetyltransferase NodL of Rhizobium leguminosarum (43). Downie (14) 5.…”

Section: Agaccttcgtcctgagatccgagctcctagtcgcgagttgcagcgacggcatcgtcggctmentioning

confidence: 99%

The chloramphenicol acetyltransferase gene of Tn2424: a new breed of cat

Parent

Roy

1992

J Bacteriol

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We have sequenced the gene coding for the chloramphenicol acetyltransferase of Tn2424 of plasmid NR79. This gene codes for a protein of 23,500 Da, and the derived protein sequence is similar to those of the chromosomal chloramphenicol acetyltransferases of Agrobacterium tumefaciens and Pseudomonas aeruginosa and of unidentified open reading frames, which may encode chloramphenicol acetyltransferases, adjacent to the ermG macrolide-lincosamide-streptogramin resistance gene of Bacillus sphaericus and the vgb virginiamycin resistance gene of Staphylococcus aureus. Weaker similarity to the LacA (thiogalactoside acetyltransferase) and CysE (serine acetyltransferase) proteins of Escherichia coli and the NodL protein of Rhizobium leguminosarum is also observed. There is no significant similarity to any other chloramphenicol acetyltransferase genes, such as that of Tn9. The Tn2424 cat gene is part of a 4.5-kb region which also contains the aacA1a aminoglycoside-6'-N-acetyltransferase gene; Tn2424 is similar to Tn21 except for the presence of this region. Sequences flanking the cat gene are typical of those flanking other genes inserted into pVS1-derived "integrons" by a site-specific recombinational mechanism.

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Characterization of the Rhizobium leguminosarum genes nodLMN involved in efficient host‐specific nodulation

Cited by 105 publications

References 51 publications

Rhizobium nodM and nodN genes are common nod genes: nodM encodes functions for efficiency of nod signal production and bacteroid maturation

Rhizobium nodM and nodN genes are common nod genes: nodM encodes functions for efficiency of nod signal production and bacteroid maturation

Characterization of the Gene Encoding Serine Acetyltransferase, a Regulated Enzyme of Cysteine Biosynthesis from the Protist ParasitesEntamoeba histolyticaand Entamoeba dispar

The chloramphenicol acetyltransferase gene of Tn2424: a new breed of cat

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