• 미생물학회지
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• 제25권4호
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• pp.290-296
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• 1987

Some streptomycin resistant strains of Rhizobium trifolii having nodulation ability were selected, and their nitrogenase activities, symbiotic effects on plant growth, and nodule electronmicroscope were compared with those of the wild type. After NTG treatment, as a mutagen, at the concentration exhibiting 99.7% lethal rate, 5 strains of streptomycin resistant mutant having nodulating ability were selected. Among these nodulating mutant strains, 3 strains produced more nodules and 2 strains showed less nodules than wild type. But their nitrogenase activities were decreased significantly, and nodule formation time was also delay compared with those of the wild type, and there was no remarkable difference in effects on plant growth. Microstructure of nodules by electronmicroscopy had mant distinctive differences between red clover nodules inoculated with wild type and mutants.

• BMB Reports
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• 제34권4호
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• pp.305-309
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• 2001

MatR in Rhizobium trifolii is a malonate-responsive transcription factor that regulates the expression of genes, matABC, enabling decarboxylation of malonyl-CoA into acetyl-CoA, synthesis of malonyl-CoA from malonate and CoA, and malonate transport. According to an analysis of the amino acid sequence homology, MatR belongs to the GntR family The proteins of this family have two-domain folds, the N-terminal helix-turn-helix DNA-binding domain and the C-terminal ligand-binding domain. In order to End the malonate binding site and amino acid residues that interact with RNA polymerase, a site-directed mutagenesis was performed. Analysis of the mutant MatR suggests that Arg-160 might be involved in malonate binding, whereas Arg-102 and Arg-174 are critical for the repression activity by interacting with RNA polymerase.

• BMB Reports
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• 제32권4호
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• pp.414-418
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• 1999

A novel gene for malonyl-CoA decarboxylase was discovered in the mat operon, which encodes a set of genes involved in the malonate metabolism of Rhizobium trifolii (An and Kim, 1998). The subunit mass determined by SDS-PAGE was 53 kDa, which correspond to the deduced mass from the sequence data. The molecular mass of the native enzyme determined by field flow fractionation was 208 kDa, indicating that R. trifolii malonyl-CoA decarboxylase is homotetrameric. R. trifolii malonyl-CoA decarboxylase converted malonyl-CoA to acetyl-CoA with a specific activity of 100 unit/mg protein. Methylmalonyl-CoA was decarboxylated with a specific activity of 0.1 unit/mg protein. p-Chloromercuribenzoate inhibited this enzyme activity, suggesting that thiol group(s) is(are) essential for this enzyme catalysis. Database analysis showed that malonyl-CoA decarboxylase from R. trifolii shared 32.7% and 28.1% identity in amino acid sequence with those from goose and human, respectively, and it would be located in the cytoplasm. However, there is no sequence homology between this enzyme and that from Saccharopolyspora erythreus, suggesting that malonyl-CoA decarboxylases from human, goose, and R. trifolii are in the same class, whereas that from S. erythreus is in a different class or even a different enzyme, methylmalonyl-CoA decarboxylase. According to the homology analysis, Cys-214 among three cysteine residues in the enzyme was found in the homologous region, suggesting that the cysteine was located at or near the active site and plays a critical role in catalysis.

• Applied Microscopy
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• 제8권1호
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• pp.9-15
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• 1978

Five strains of the Genus Rhizobium were isolated from the nodules of five leguminous plants respectively. They were identified according to Bergey's Manual together with the results of Vincent. The flagella of each strains were observed by electron microscope using negative staining with PTA and metal shadowing with chromium. Five host plants and identified Rhizobium strains were as. follows. Pisum sativum.....R. leguminosarum Phaseolus vulgaris.....R. phaseoli Trifolium repens.....R. trifolii Glycine max.....R. japonicum Lupinus grandiflorus.....R. lupini Electron micrographs showed that R. leguminosarum and R. phaseoli had 4 peritrichous flagella, where as R. trifolii had 5 peritrichous flagella. On the other hand, R. japonicum and R. lupini had 1 subpolar flagellum.

• 미생물학회지
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• 제22권2호
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• pp.73-76
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• 1984

From the root nodules of legumes distributed in South Korea, 74 strains of Rhizobium were isolated. The strains isolated were identified based on Bergey's Manual and Vincent's identification key. Following 5 species of Rhizobium were confirmed. R. leguminosarum, R. meliloti, R. phaseoli, R. trifolii, and R. japonicum

• BMB Reports
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• 제35권5호
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• pp.443-451
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• 2002

Malonate is a three-carbon dicarboxylic acid. It is well known as a competitive inhibitor of succinate dehydrogenase. It occurs naturally in biological systems, such as legumes and developing rat brains, which indicates that it may play an important role in symbiotic nitrogen metabolism and brain development. Recently, enzymes that are related to malonate metabolism were discovered and characterized. The genes that encode the enzymes were isolated, and the regulation of their expression was also studied. The mutant bacteria, in which the malonate-metabolizing gene was deleted, lost its primary function, symbiosis, between Rhizobium leguminosarium bv trifolii and clover. This suggests that malonate metabolism is essential in symbiotic nitrogen metabolism, at least in clover nodules. In addition to these, the genes matB and matC have been successfully used for generation of the industrial strain of Streptomyces for the production of antibiotics.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1485-1488
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• 2006

• 미생물학회지
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• 제29권1호
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• pp.40-48
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• 1991

Two malonate-specific enzymes, malonyl-CoA synthetase and malonamidase, were found in free-living cultures of Rhizobium japonicum, Rhizobium meliloti, and Rhizobium trifolii, that infect plant roots where contain a high concentration of malonate. Malonyl-CoA synthetase catalyzes the formation of malonyl-CoA, AMP, and PPi directly from malonate, coenzyme A, and ATP in the presence of $Mg^{2+}$ Malonamidase is a novel enzyme that catalyzes hydrolysis and malonyl transfer of malonamate, and forms malonohydroxamate from malonate and hydroxylamine. Both enzymes are highly specific for malonate. These results show that Rhizobia have enzymes able to metabolize malonate and suggest that malonate may be used in symbiotic carbon and nitrogen metabolism.

• Applied Biological Chemistry
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• 제28권3호
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• pp.149-155
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• 1985

전국(全國) 223개(個) 지역(地域)에서 수집(蒐集)한 두과작물(豆科作物)의 근류(根瘤)에서 총(總) 590주(株)의 근류균(根瘤菌)을 분리(分離)하여 숙주특이성(宿主特異性)에 따라, R. japonicum 218종(種), R. phaseoli 101종(種), R. trifolii 97종(種), R. meliloti 4종(種), R. leguminosarum 1종(種), Rhizobium species 101종(種), 미분류(未分類)된 균주(菌株) 159종(種)으로 분류(分類)하였다. 분리(分離)된 R. japonicum 218종(種)의 근류형성능(根瘤形成能)과 질소고정능(窒素固定能)을 비교(比較)하여. R. japonicum R-138, R-168, R-214 균주(菌株)를 우수균주(優秀菌株)로 하였다. 분리(分離) 선발(選拔)된 R. japonicum 중(中) 질소고정능(窒素固定能)이 우수(優秀)한 균주(菌株)의 plasmid를 확인(確認)한 결과(結果), fast-growing group 균주(菌株)들은 $1{\sim}4$개(個)의 거대(巨大) plasmid를 함유(含有)하고 있었으며 그 분자량(分子量)은 약(約) $35{\sim}300{\;}Md$ 정도(程度)이었다. 반면 대부분(大部分)의 slow-growing group 균주(菌株)들은 plasmid가 검출(檢出)되지 않았다.

• Bulletin of the Korean Chemical Society
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• 제15권5호
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• pp.394-399
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• 1994

The catalytic mechanism of malonyl-CoA synthetase from Rhizobium trifolii was investigated by the steady state kinetics and intermediate identification. Initial velocity studies and the product inhibition studies with AMP and PPi strongly suggested ordered Bi Uni Uni Bi Ping-Pong Ter Ter system as the most probable steady state kinetic mechanism of malonyl-CoA synthetase. Michaelis constants were $0.17{\pm}0.04 {\mu}M,\;0.24{\pm}0.18 {\mu}M\;and\;0.045{\pm}0.26 {\mu}$M for ATP, malonate and CoA, respectively. The TLC analysis of the $^{32}P-labelled$ products in reaction mixture containing $[{\gamma}-^{32}P]$ ATP in the absence of CoA showed that PPi was produced after the sequential addition of ATP and malonate. Formation of malonyl-AMP, suggested as an intermediate in the kinetically deduced mechanism, was confirmed by the analysis of $^{31}P-NMR$ spectra of AMP product isolated from the $^{18}O$ transfer experiment using $[^{18}O]$malonate. Two resonances were observed, corresponding to AMP labelled with zero and one atom of $^{18}O$, indicating that one atom of $^{18}O$ transferred from $[^{18}O]$malonate to AMP through the formation of malonyl-AMP. Formation of malonyl-AMP was also confirmed through the TLC analysis of reaction mixture containing $[{\alpha}-^{32}P]$ATP. These results strongly support the ordered Bi Uni Uni Bi Ping-Pong Ter Ter mechanism deduced from the initial velocity and product inhibition studies.