Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutants of the Escherichia coli initiator tRNA (tRNA(fMet)) have been used to examine the role of the anticodon and discriminator base in in vivo aminoacylation of tRNAs by cysteinyl-tRNA synthetase. Substitution of the methionine anticodon CAU with the cysteine anticodon GCA was found to allow initiation of protein synthesis by the mutant tRNA from a complementary initiation codon in a reporter protein. Sequencing of the protein revealed that cysteine comprised about half of the amino acid at the N terminus. An additional mutation, converting the discriminator base of tRNA(GCAfMet) from A73 to the base present in tRNA(Cys) (U73), resulted in a 6-fold increase in the amount of protein produced and insertion of greater than or equal to 90% cysteine in response to the complementary initiation codon. Substitution of C73 or G73 at the discriminator position led to insertion of little or no cysteine, indicating the importance of U73 for recognition of the tRNA by cysteinyl-tRNA synthetase. Single base changes in the anticodon of tRNA(GCAfMet) containing U73 from GCA to UCA, GUA, GCC, and GCG (changes underlined) eliminated or dramatically reduced cysteine insertion by the mutant initiator tRNA indicating that all three cysteine anticodon bases are essential for specific aminoacylation of the tRNA with cysteine in vivo.
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PMID:The anticodon and discriminator base are major determinants of cysteine tRNA identity in vivo. 137 31

CDC group M-6 is the vernacular name given to a gram-negative, oxidase-positive, aerobic, nonmotile, rod-shaped bacterium. This organism is biochemically similar to Kingella denitrificans and displays a cellular fatty acid profile consistent with CDC groups M-5 and EF-4 and with Neisseria elongata. Of the 95 M-6 strains referred to the Centers for Disease Control (CDC) for identification, 32 (64%) of the first 50 were from the throat or sputum and only 3 (6%) were from blood; only 5 (11%) of the next 45 isolates were from the upper respiratory tract and 23 (51%) were from blood, with many of these (15 or 65%) being associated with endocarditis. The major characteristics of CDC group M-6 include reduction of nitrate and nitrite with no gas formation; positive reaction for oxidase; negative reactions for catalase, urease, indole, and motility; and no acid production from carbohydrates. Guanine-plus-cytosine content determined spectrophotometrically by thermal denaturation was 55 to 58 mol % for six M-6 strains tested: 56 mol % for the N. elongata subsp. elongata type strain and for the N. elongata subsp. glycolytica type strain. By the hydroxyapatite method, DNAs from 24 M-6 strains showed an average of 78% relatedness to M-6 reference strain B1019 in reactions at 60 degrees C and 73% relatedness in reactions at 75 degrees C. M-6 strain B1019 was 79% related to the N. elongata type strain at 60 degrees C and 71% related at 75 degrees C; it was 75% related to the type strain N. elongata subsp. glycolytica at 60 degrees C and was 66% related at 75 degrees C. DNAs from CDC group EF-4, K. denitrificans, and CDC group M-5 were all less than 14% related to CDC group M-6 at 75 degrees C. The DNA relatedness data showed conclusively that all the M-6 strains belong in the species N. elongata. M-6 is different from N. elongata subsp. elongata in that M-6 reduces nitrate and sometimes weakly acidifies D-glucose, and it is different from N. elongata subsp. glycolytica in that it reduces nitrate and is negative for glucose and catalase. Because of the apparent clinical significance of M-6 compared with the clinical significance of N. elongata subsp. elongata and N. elongata subsp. glycolytica and the ease in distinguishing it biochemically, we propose M-6 as a third subspecies of N.elongata, N. elongata subsp. nitroreducens subsp. nov.
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PMID:Neisseria elongata subsp. nitroreducens subsp. nov., formerly CDC group M-6, a gram-negative bacterium associated with endocarditis. 227 87