scholarly journals A Sinorhizobium meliloti Lipopolysaccharide Mutant Induces Effective Nodules on the Host Plant Medicago sativa (Alfalfa) but Fails to Establish a Symbiosis with Medicago truncatula

1998 ◽  
Vol 11 (9) ◽  
pp. 906-914 ◽  
Author(s):  
K. Niehaus ◽  
A. Lagares ◽  
A. Pühler
Keyword(s):  
Sinorhizobium Meliloti ◽  
Uv Light ◽  
Root Nodules ◽  
Sodium Dodecyl ◽  
Microscopic Analysis ◽  
Wild Type ◽  
Electron Microscopic ◽  
Molecular Weights ◽  
Infection Threads ◽  
Dna Fragment

The specific Sinorhizobium meliloti lipopolysaccharide (LPS) mutant Rm6963 (A. Lagares, G. Caetano Anolles, K. Niehaus, J. Lorenzen, H. D. Ljunggren, A. Puhler, and G. Favelukes, J. Bacteriol. 174:5941-5952, 1992) was shown to be mutated in a region corresponding to a cloned 5-kb SstI DNA fragment that was able to complement the lpsB and lpsC mutants of S. meliloti described by Clover et al. (R. H. Clover, J. Kieber, and E. R. Signer, J. Bacteriol. 171:3961-3967, 1989). Sodium dodecyl sulfate polyacryla-mide electrophoresis revealed that the LPS-I and LPS-II fractions of the LPS mutant Rm6963 were shifted to lower molecular weights. While the majority of the Medicago spp. tested established an effective symbiosis with both the S. meliloti wild-type Rm2011 and the LPS mutant Rm6963, the latter induced ineffective nodules on M. truncatula. A light- and electron-microscopic analysis of the ineffective M. truncatula root nodules revealed that the bacteria were released from the infection threads but failed to colonize the plant cells effectively. The plant cytoplasm was filled with numerous vesicles, probably the result of a disturbed bacteroid development. Sections of ineffective M. truncatula root nodules induced by the LPS mutant Rm6963 showed brown, necrotic cells within the central nodule tissue that autofluoresced when viewed under UV light. These observations are best explained by a plant defense response. Evidently, the rhizobial LPS plays a role in plant-microbe signaling during the formation of M. truncatula nodules.

scholarly journals Transformation-deficient mutants of Bacillus subtilis impaired in competence-specific nuclease activities

1982 ◽  
Vol 152 (1) ◽  
pp. 166-174
Author(s):  
J A Mulder ◽  
G Venema
Keyword(s):  
Molecular Weight ◽  
Bacillus Subtilis ◽  
Sodium Dodecyl Sulfate ◽  
Sodium Dodecyl ◽  
Magnesium Ions ◽  
Polyacrylamide Gels ◽  
Wild Type ◽  
Molecular Weights ◽  
Defective Mutant ◽  
Mutant Strains

A comparison of the nucleolytic activities in competent and physiologically low-competent wild-type cultures of Bacillus subtilis in DNA-containing sodium dodecyl sulfate-polyacrylamide gels revealed the existence of three competence-associated nuclease activities with apparent molecular weights of 13,000, 15,000, and 26,000. The three activities, which were dependent on manganese or magnesium ions, were specifically present in the competent fraction of a competent culture. The competence-associated nucleolytic activities of eight transformation-defective mutant strains were assayed, resulting in the following three classes of mutants: (i) four strains which, according to this assay, were not impaired in any of the nucleolytic activities mentioned above; (ii) one strain which was strongly impaired in the 13,000- and 26,000-molecular-weight activities, but showed a considerable level of the 15,000-molecular-weight activity; and (iii) three strains which were severely impaired in all three activities. The results indicated that the 26,000-molecular-weight activity was a dimer of the 13,000-molecular-weight activity and that this nuclease was involved in the entry of DNA.

scholarly journals The molecular chaperone Hsp90α deficiency causes retinal degeneration by disrupting Golgi organization and vesicle transportation in photoreceptors

2019 ◽  
Vol 12 (3) ◽  
pp. 216-229 ◽  
Author(s):  
Yuan Wu ◽  
Xiudan Zheng ◽  
Yubo Ding ◽  
Min Zhou ◽  
Zhuang Wei ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Molecular Chaperone ◽  
Outer Segment ◽  
Microscopic Analysis ◽  
Heat Shock Protein 90 ◽  
Hsp90 Inhibitor ◽  
Wild Type ◽  
Electron Microscopic ◽  
Golgi Organization ◽  
Deficient Mice

Abstract Heat shock protein 90 (Hsp90) is an abundant molecular chaperone with two isoforms, Hsp90α and Hsp90β. Hsp90β deficiency causes embryonic lethality, whereas Hsp90α deficiency causes few abnormities except male sterility. In this paper, we reported that Hsp90α was exclusively expressed in the retina, testis, and brain. Its deficiency caused retinitis pigmentosa (RP), a disease leading to blindness. In Hsp90α-deficient mice, the retina was deteriorated and the outer segment of photoreceptor was deformed. Immunofluorescence staining and electron microscopic analysis revealed disintegrated Golgi and aberrant intersegmental vesicle transportation in Hsp90α-deficient photoreceptors. Proteomic analysis identified microtubule-associated protein 1B (MAP1B) as an Hsp90α-associated protein in photoreceptors. Hspα deficiency increased degradation of MAP1B by inducing its ubiquitination, causing α-tubulin deacetylation and microtubule destabilization. Furthermore, the treatment of wild-type mice with 17-DMAG, an Hsp90 inhibitor of geldanamycin derivative, induced the same retinal degeneration as Hsp90α deficiency. Taken together, the microtubule destabilization could be the underlying reason for Hsp90α deficiency-induced RP.

scholarly journals Ifm(2)2 is a myosin heavy chain allele that disrupts myofibrillar assembly only in the indirect flight muscle of Drosophila melanogaster.

1988 ◽  
Vol 107 (6) ◽  
pp. 2613-2621 ◽  
Author(s):  
M Chun ◽  
S Falkenthal
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Flight Muscle ◽  
Microscopic Analysis ◽  
Thick Filament ◽  
Indirect Flight Muscle ◽  
Chain Gene ◽  
Wild Type ◽  
Electron Microscopic ◽  
Sarcomere Assembly

Using a combination of molecular and genetic techniques we demonstrate that Ifm(2)2 is an allele of the single-copy sarcomeric myosin heavy chain gene. Flies homozygous for this allele accumulate wild-type levels of mRNA and protein in tubular muscle of adults, but fail to accumulate detectable amounts of myosin heavy chain mRNA or protein in the indirect flight muscle. We propose that the mutation interferes with either transcription of the gene or splicing of the primary transcript in the indirect flight muscle and not in other muscle tissues. Biochemical and electron microscopic analysis of flies homozygous for this mutation has revealed that thick filament assembly is abolished in the indirect flight muscle resulting in the instability of wild-type thick filament proteins. In contrast, thin filament and Z disc assembly are marginally affected. We discuss a working hypothesis for sarcomere assembly and define and experimental approach to test the predictions of this proposed pathway for sarcomere assembly.

Electron microscopic observations of infection threads in driselase treated nodules of Astragalus sinicus

1986 ◽  
Vol 32 (12) ◽  
pp. 947-952 ◽  
Author(s):  
Shiro Higashi ◽  
Kazuya Kushiyama ◽  
Mikiko Abe
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Root Nodules ◽  
Morphological Characteristics ◽  
Enzyme Treatment ◽  
Vascular Bundles ◽  
Electron Microscopic ◽  
Astragalus Sinicus ◽  
Infection Threads

The morphological characteristics of infection threads in the root nodules of Astragalus sinicus were examined by scanning and transmission electron microscopy. The infection threads, epidermal cell walls, and vascular bundles of the nodule were not altered when a nodule was treated with driselase (a plant cell wall degrading enzyme), although the cell walls of meristematic and bacteroid-including zones were completely decomposed by the enzyme treatment. Some infection threads were funnel shaped at the site of attachment of the infection thread to the host cell wall.

scholarly journals Malic Enzyme Cofactor and Domain Requirements for Symbiotic N2 Fixation by Sinorhizobium meliloti

2006 ◽  
Vol 189 (1) ◽  
pp. 160-168 ◽  
Author(s):  
Michael J. Mitsch ◽  
Alison Cowie ◽  
Turlough M. Finan
Keyword(s):  
Amino Acid ◽  
Malic Enzyme ◽  
Sinorhizobium Meliloti ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
High Ratio ◽  
Terminal Region ◽  
Wild Type ◽  
Mutant Strains ◽  
Alfalfa Root

ABSTRACT The NAD+-dependent malic enzyme (DME) and the NADP+-dependent malic enzyme (TME) of Sinorhizobium meliloti are representatives of a distinct class of malic enzymes that contain a 440-amino-acid N-terminal region homologous to other malic enzymes and a 330-amino-acid C-terminal region with similarity to phosphotransacetylase enzymes (PTA). We have shown previously that dme mutants of S. meliloti fail to fix N2 (Fix−) in alfalfa root nodules, whereas tme mutants are unimpaired in their N2-fixing ability (Fix+). Here we report that the amount of DME protein in bacteroids is 10 times greater than that of TME. We therefore investigated whether increased TME activity in nodules would allow TME to function in place of DME. The tme gene was placed under the control of the dme promoter, and despite elevated levels of TME within bacteroids, no symbiotic nitrogen fixation occurred in dme mutant strains. Conversely, expression of dme from the tme promoter resulted in a large reduction in DME activity and symbiotic N2 fixation. Hence, TME cannot replace the symbiotic requirement for DME. In further experiments we investigated the DME PTA-like domain and showed that it is not required for N2 fixation. Thus, expression of a DME C-terminal deletion derivative or the Escherichia coli NAD+-dependent malic enzyme (sfcA), both of which lack the PTA-like region, restored wild-type N2 fixation to a dme mutant. Our results have defined the symbiotic requirements for malic enzyme and raise the possibility that a constant high ratio of NADPH + H+ to NADP in nitrogen-fixing bacteroids prevents TME from functioning in N2-fixing bacteroids.

scholarly journals Tubulin as a molecular component of coated vesicles.

1983 ◽  
Vol 97 (4) ◽  
pp. 1191-1199 ◽  
Author(s):  
W G Kelly ◽  
A Passaniti ◽  
J W Woods ◽  
J L Daiss ◽  
T F Roth
Keyword(s):  
Microscopic Analysis ◽  
Bovine Brain ◽  
Coated Vesicles ◽  
Antigenic Determinants ◽  
Molecular Component ◽  
Electron Microscopic ◽  
Molecular Weights ◽  
Controlled Pore Glass ◽  
Sds Page ◽  
Pore Glass

Two proteins of 53,000 and 56,000 mol wt have been found to be associated with coated vesicles (CV) purified from bovine brain and chicken liver. These proteins share molecular weights, isoelectric points, and antigenic determinants with alpha- and beta-tubulins purified from bovine brain. Based on SDS PAGE and electron microscopic analysis of controlled pore glass bead exclusion column fractions, both the tubulins and the major CV polypeptide clathrin were found to chromatograph as components of a single kinetic particle. In addition, tubulin and CV antigens assayed by a sensitive enzyme-linked-immunoadsorbent method eluted from the columns with constant stoichiometry. These data provide evidence that tubulin is a molecular component of coated vesicles.

scholarly journals Morphogenesis of root nodules in white clover. II. The effect of mutation in genes nod IJ of the microsymbiont upon the nodule structure

2014 ◽  
Vol 67 (1) ◽  
pp. 5-22
Author(s):  
Barbara Łotocka ◽  
Joanna Kopcińska ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Single Cells ◽  
Wild Strain ◽  
Root Hairs ◽  
Nodule Development ◽  
Wild Type ◽  
Delayed Reaction ◽  
Infection Threads

Morphogenesis of ineffective root nodules initiated on the roots of white clover 'Astra' by the <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em> strains ANU261 (Tn5 insertion in nod 1 gene) and ANU262 (Tn5 insertion in nod J gene) was investigated. Following changes were observed, as compared to the wild-type nodulation: the exaggerated, not delayed reaction of root hairs; the delay in nodulation with the number of nodules the same as in plants inoculated with a wild strain; the formation and organization of the nodule primordium not changed in comparison with the wild-type nodules; infection threads abnormally branched and diffusing with bacteria deprived of light zone and enriched with storage material; infected cells of bacteroidal tissue abnormally strongly osmiophilic and only slightly vacuolated; symbiosomes with very narrowed peribacteroidal space, subject to premature degradation; abnormal accumulation of starch in the nodule tissues; nodule development blocked at the stage of laterally situated meristem and single nodule bundle; inhibition of divisions in the meristem and vacuolation of its cells; the appearance of single cells with colonies of saprophytic rhizobia embedded in the fibrillar matrix in the old, degraded regions of the bacteroidal tissue.

scholarly journals Phosphate Assimilation in Rhizobium(Sinorhizobium) meliloti: Identification of apit-Like Gene

1998 ◽  
Vol 180 (16) ◽  
pp. 4219-4226 ◽  
Author(s):  
Sylvie D. Bardin ◽  
Ralf T. Voegele ◽  
Turlough M. Finan
Keyword(s):  
Transport System ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Phosphate Transport ◽  
Wild Type ◽  
Transcription Start ◽  
Present Evidence ◽  
Suppressor Mutations ◽  
Mutant Cells

ABSTRACT Rhizobium meliloti mutants defective in thephoCDET-encoded phosphate transport system form root nodules on alfalfa plants that fail to fix nitrogen (Fix−). We have previously reported that two classes of second-site mutations can suppress the Fix− phenotype ofphoCDET mutants to Fix+. Here we show that one of these suppressor loci (sfx1) contains two genes, orfA and pit, which appear to form an operon transcribed in the order orfA-pit. The Pit protein is homologous to various phosphate transporters, and we present evidence that three suppressor mutations arose from a single thymidine deletion in a hepta-thymidine sequence centered 54 nucleotides upstream of the orfA transcription start site. This mutation increased the level of orfA-pit transcription. These data, together with previous biochemical evidence, show that theorfA-pit genes encode a Pi transport system that is expressed in wild-type cells grown with excess Pibut repressed in cells under conditions of Pi limitation. In phoCDET mutant cells, orfA-pitexpression is repressed, but this repression is alleviated by the second-site suppressor mutations. Suppression increasesorfA-pit expression compensating for the deficiencies in phosphate assimilation and symbiosis of the phoCDETmutants.

A New Genetic Locus in Sinorhizobium meliloti Is Involved in Stachydrine Utilization

1998 ◽  
Vol 64 (10) ◽  
pp. 3954-3960 ◽  
Author(s):  
Donald A. Phillips ◽  
Eve S. Sande ◽  
J. A. C. Vriezen ◽  
Frans J. de Bruijn ◽  
Daniel Le Rudulier ◽  
...  
Keyword(s):  
Salt Stress ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Genetic Locus ◽  
Wild Type ◽  
Single Strain ◽  
Reading Frame ◽  
Carbon And Nitrogen ◽  
Promoter Probe ◽  
Inducible Genes

ABSTRACT Stachydrine, a betaine released by germinating alfalfa seeds, functions as an inducer of nodulation genes, a catabolite, and an osmoprotectant in Sinorhizobium meliloti. Two stachydrine-inducible genes were found in S. meliloti1021 by mutation with a Tn5-luxAB promoter probe. Both mutant strains (S10 and S11) formed effective alfalfa root nodules, but neither grew on stachydrine as the sole carbon and nitrogen source. When grown in the absence or presence of salt stress, S10 and S11 took up [14C]stachydrine as well as wild-type cells did, but neither used stachydrine effectively as an osmoprotectant. In the absence of salt stress, both S10 and S11 took up less [14C]proline than wild-type cells did. S10 and S11 appeared to colonize alfalfa roots normally in single-strain tests, but when mixed with the wild-type strain, their rhizosphere counts were reduced more than 50% (P ≤ 0.01) relative to the wild type. These results suggest that stachydrine catabolism contributes to root colonization. DNA sequence analysis identified the mutated locus in S11 as putA, and the luxABfusion in that gene was induced by proline as well as stachydrine. DNA that restored the capacity of mutant S10 to catabolize stachydrine contained a new open reading frame, stcD. All data are consistent with the concept that stcD codes for an enzyme that produces proline by demethylation of N-methylproline, a degradation product of stachydrine.

On the Evolution of an Oligocephalic Enzyme. Glutamine- Chorismate-Amidotransferase-Free Anthranilate Phosphoribosyltransferases from Mutant Strains of Salmonella typhimurium

1978 ◽  
Vol 33 (3-4) ◽  
pp. 235-244 ◽  
Author(s):  
Manfred Grieshaber
Keyword(s):  
Molecular Weight ◽  
Sodium Dodecyl Sulfate ◽  
Salmonella Typhimurium ◽  
Sodium Dodecyl ◽  
Single Component ◽  
Wild Type ◽  
Molecular Weights ◽  
Mutant Strains ◽  
Dodecyl Sulfate

(1) A procedure has been described for the purification of two glutamine-chorismate-amido- transferase-free anthranilate phosphoribosyltransferases from mutant strains TAX6trpR782 and trpAB1653trpR782 of Salmonella typhimurium.(2) The native enzymes tend to aggregate forming polymers of molecular weights 333,000 in the case of TAXtrpR782 and 220,000 and larger than 1X106 in the case of trpABI653trpR782. In the presence of sodium dodecyl sulfate the polymer of trpAB1653trpR782 dissociates into a single component with molecular weight of 72,000.(3) In contrast to anthranilate phosphoribosyltransferase of the wild type component II, the glutamine-chorismate-amidotransferase-free proteins do not complex with component I. They do however show catalytical similarities with the wild type with respect to anthranilate phosphoribosyltransferase activity.

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