Many enzymes which catalyze the conversion of large substrates are made of several structural domains belonging to the same polypeptide chain. Transfer RNA (tRNA), one of the substrates of the multidomain aminoacyl-tR...Many enzymes which catalyze the conversion of large substrates are made of several structural domains belonging to the same polypeptide chain. Transfer RNA (tRNA), one of the substrates of the multidomain aminoacyl-tRNA synthetases (aaRS), is an L-shaped molecule whose size in one dimension is similar to that of its cognate aaRS. Crystallographic structures of aaRS/tRNA complexes show that these enzymes use several of their structural domains to interact with their cognate tRNA. This mini review discusses first some aspects of the evolution and of the flexibility of the pentadomain bacterial glutamyl-tRNA synthetase (GluRS) revealed by kinetic and interaction studies of complementary truncated forms, and then illustrates how stable analogues of aminoacyl-AMP intermediates have been used to probe conformational changes in the active sites of Escherichia coli GluRS and of the nondiscriminating aspartyl-tRNA synthetase (ND-AspRS) of Pseudomonas aeruginosa.展开更多
Objectives: In the present study, we have sought to establish the clinical and immunological characteristics of Japanese patients with interstitial lung disease (ILD). Methods: Serum samples from 35 patients of ILD we...Objectives: In the present study, we have sought to establish the clinical and immunological characteristics of Japanese patients with interstitial lung disease (ILD). Methods: Serum samples from 35 patients of ILD were screened for autoantibodies using RNA and protein immunoprecipitation assays. Patients with or without serum antibodies to aminoacyl tRNA synthetases (ARS) were assessed clinically and compared. Results: Sera from 12 of 35 (34%) patients with ILD (mean age at onset = 49.7 yrs;range 27 - 65 yrs) were found to contain anti-ARS antibodies (anti-EJ: 3 patients;anti-OJ: 2 patients;anti-PL-12: 3 patients;anti-KS: 4 patients). Nine of the 12 (75%) were female. Six (50%) had Raynaud’s phenomenon, 5 (42%) had arthralgia/arthritis and four (33%) had rheumatoid factor. Lung biopsy specimens of 8 patients with anti-ARS antibodies were examined histologically in detail. The following was determined: Two patients had usual interstitial pneumonia;3 had non-specific interstitial pneumonia;one had organizing pneumonia;one had lymphocyte interstitial pneumonia and the remaining patient had desquamative interstitial pneumonia. Age at disease onset was significantly lower and the frequency of Raynaud’s phenomenon was significantly greater in these patients compared to anti-ARS-negative patients (49.7 yrs vs. 62.6 yrs, p = 0.004;50% vs. 4%, p = 0.003, respectively). Conclusions: These results indicate that the presence of anti-ARS autoantibodies correlates with ILD without definite diagnosis of connective tissue diseases as well as polymyositis/dermatomyositis (PM/DM) with ILD in Japanese patients.展开更多
Escherichia coli leucyl-tRNA synthetase (LeuRS) is one of aminoacyl-tRNA synthetases (aaRSs) and belongs to class 1 aaRSs. The apparent steady-state kinetics of the aminoacylation reaction catalyzed by LeuRS in the pr...Escherichia coli leucyl-tRNA synthetase (LeuRS) is one of aminoacyl-tRNA synthetases (aaRSs) and belongs to class 1 aaRSs. The apparent steady-state kinetics of the aminoacylation reaction catalyzed by LeuRS in the presence of some RE3+ were studied. The results show that Mg2+ can be substituted by RE3+ for the aminoacylation reaction. The apparent K-m values for ATP and leucine are markedly different between native and Mg2+-free tRNA(1)(Leu). At high concentration of ATP there is inhibitory effect on Mg2+-free tRNA but not on native tRNA, which indicates that metal ions are a substrate of the aminoacylation reaction.展开更多
文摘Many enzymes which catalyze the conversion of large substrates are made of several structural domains belonging to the same polypeptide chain. Transfer RNA (tRNA), one of the substrates of the multidomain aminoacyl-tRNA synthetases (aaRS), is an L-shaped molecule whose size in one dimension is similar to that of its cognate aaRS. Crystallographic structures of aaRS/tRNA complexes show that these enzymes use several of their structural domains to interact with their cognate tRNA. This mini review discusses first some aspects of the evolution and of the flexibility of the pentadomain bacterial glutamyl-tRNA synthetase (GluRS) revealed by kinetic and interaction studies of complementary truncated forms, and then illustrates how stable analogues of aminoacyl-AMP intermediates have been used to probe conformational changes in the active sites of Escherichia coli GluRS and of the nondiscriminating aspartyl-tRNA synthetase (ND-AspRS) of Pseudomonas aeruginosa.
文摘Objectives: In the present study, we have sought to establish the clinical and immunological characteristics of Japanese patients with interstitial lung disease (ILD). Methods: Serum samples from 35 patients of ILD were screened for autoantibodies using RNA and protein immunoprecipitation assays. Patients with or without serum antibodies to aminoacyl tRNA synthetases (ARS) were assessed clinically and compared. Results: Sera from 12 of 35 (34%) patients with ILD (mean age at onset = 49.7 yrs;range 27 - 65 yrs) were found to contain anti-ARS antibodies (anti-EJ: 3 patients;anti-OJ: 2 patients;anti-PL-12: 3 patients;anti-KS: 4 patients). Nine of the 12 (75%) were female. Six (50%) had Raynaud’s phenomenon, 5 (42%) had arthralgia/arthritis and four (33%) had rheumatoid factor. Lung biopsy specimens of 8 patients with anti-ARS antibodies were examined histologically in detail. The following was determined: Two patients had usual interstitial pneumonia;3 had non-specific interstitial pneumonia;one had organizing pneumonia;one had lymphocyte interstitial pneumonia and the remaining patient had desquamative interstitial pneumonia. Age at disease onset was significantly lower and the frequency of Raynaud’s phenomenon was significantly greater in these patients compared to anti-ARS-negative patients (49.7 yrs vs. 62.6 yrs, p = 0.004;50% vs. 4%, p = 0.003, respectively). Conclusions: These results indicate that the presence of anti-ARS autoantibodies correlates with ILD without definite diagnosis of connective tissue diseases as well as polymyositis/dermatomyositis (PM/DM) with ILD in Japanese patients.
文摘Escherichia coli leucyl-tRNA synthetase (LeuRS) is one of aminoacyl-tRNA synthetases (aaRSs) and belongs to class 1 aaRSs. The apparent steady-state kinetics of the aminoacylation reaction catalyzed by LeuRS in the presence of some RE3+ were studied. The results show that Mg2+ can be substituted by RE3+ for the aminoacylation reaction. The apparent K-m values for ATP and leucine are markedly different between native and Mg2+-free tRNA(1)(Leu). At high concentration of ATP there is inhibitory effect on Mg2+-free tRNA but not on native tRNA, which indicates that metal ions are a substrate of the aminoacylation reaction.
