scholarly journals The aminoacylation of transfer ribonucleic acid. Recognition of methionine by Escherichia coli methionyl-transfer ribonucleic acid synthetase

1977 ◽  
Vol 165 (2) ◽  
pp. 367-373 ◽  
Author(s):  
J M Old ◽  
D S Jones
Keyword(s):  
Escherichia Coli ◽  
Active Site ◽  
Ribonucleic Acid ◽  
Chemical Nature ◽  
Trna Synthetase ◽  
Side Chain ◽  
Amino Acid Side Chain ◽  
Sulphur Atom ◽  
Recognition Mechanism ◽  
Methionyl Trna Synthetase

The mechanism of the recognition of methionine by Escherichia coli methionyl-tRNA synthetase was examined by a kinetic study of the recognition of methionine analogues in the ATP-PPi exchange reaction and the tRNA-aminoacylation reaction. The results show that the recognition mechanism consists of three parts: (1) the recognition of the size, shape and chemical nature of the amino acid side chain at the methionine-binding stage of the reaction; (2) the recognition of the length of the side chain at the stage of aminoacyl-adenylate complex-formation; (3) the recognition of the sulphur atom in the side chain at the stage of methionyl-tRNA formation. It is proposed that the sulphur atom interacts with the enzyme to induce a conformational change. A model of the active site incorporating the mechanism of methionine recognition is presented.

scholarly journals Use of β3-methionine as an amino acid substrate of Escherichia coli methionyl-tRNA synthetase

2020 ◽  
Vol 209 (2) ◽  
pp. 107435 ◽  
Author(s):  
Giuliano Nigro ◽  
Sophie Bourcier ◽  
Christine Lazennec-Schurdevin ◽  
Emmanuelle Schmitt ◽  
Philippe Marlière ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Trna Synthetase ◽  
Methionyl Trna Synthetase ◽  
Acid Substrate ◽  
Amino Acid Substrate

scholarly journals Crystal structures of two monomeric triosephosphate isomerase variants identifiedviaa directed-evolution protocol selecting forL-arabinose isomerase activity

2016 ◽  
Vol 72 (6) ◽  
pp. 490-499
Author(s):  
Mirja Krause ◽  
Tiila-Riikka Kiema ◽  
Peter Neubauer ◽  
Rik K. Wierenga
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Directed Evolution ◽  
Crystal Structures ◽  
Active Site ◽  
Triosephosphate Isomerase ◽  
Point Mutations ◽  
Van Der Waals Interactions ◽  
Side Chain ◽  
Arabinose Isomerase

The crystal structures are described of two variants of A-TIM: Ma18 (2.7 Å resolution) and Ma21 (1.55 Å resolution). A-TIM is a monomeric loop-deletion variant of triosephosphate isomerase (TIM) which has lost the TIM catalytic properties. Ma18 and Ma21 were identified after extensive directed-evolution selection experiments using anEscherichia coliL-arabinose isomerase knockout strain expressing a randomly mutated A-TIM gene. These variants facilitate better growth of theEscherichia coliselection strain in medium supplemented with 40 mML-arabinose. Ma18 and Ma21 differ from A-TIM by four and one point mutations, respectively. Ma18 and Ma21 are more stable proteins than A-TIM, as judged from CD melting experiments. Like A-TIM, both proteins are monomeric in solution. In the Ma18 crystal structure loop 6 is open and in the Ma21 crystal structure loop 6 is closed, being stabilized by a bound glycolate molecule. The crystal structures show only small differences in the active site compared with A-TIM. In the case of Ma21 it is observed that the point mutation (Q65L) contributes to small structural rearrangements near Asn11 of loop 1, which correlate with different ligand-binding properties such as a loss of citrate binding in the active site. The Ma21 structure also shows that its Leu65 side chain is involved in van der Waals interactions with neighbouring hydrophobic side-chain moieties, correlating with its increased stability. The experimental data suggest that the increased stability and solubility properties of Ma21 and Ma18 compared with A-TIM cause better growth of the selection strain when coexpressing Ma21 and Ma18 instead of A-TIM.

scholarly journals Methionyl-tRNA Synthetase from Escherichia coli

2005 ◽  
Vol 127 (3) ◽  
pp. 449-457 ◽  
Author(s):  
David G. BARKER ◽  
Jean-Pierre EBEL ◽  
Ross JAKES ◽  
Chris J. BRUTON
Keyword(s):  
Escherichia Coli ◽  
Trna Synthetase ◽  
Methionyl Trna Synthetase

A new method for the isolation of methionyl transfer RNA synthetase mutants from Escherichia coli

1975 ◽  
Vol 21 (6) ◽  
pp. 754-758 ◽  
Author(s):  
John B. Armstrong ◽  
John A. Fairfield
Keyword(s):  
Escherichia Coli ◽  
Trna Synthetase ◽  
Transfer Rna ◽  
New Method ◽  
Wild Type ◽  
E Coli ◽  
Adenosyl Methionine ◽  
K 12 ◽  
Methionyl Trna Synthetase

Six methionine auxotrophs were isolated from an E. coli K-12 strain which required up to 100 times as much methionine for growth as a conventional auxotroph. In these mutants, the methionyl-tRNA synthetase had an increased Km for methionine. The Km value for the mutants ranged from 0.48 to 1.63 mM, compared to 0.078 mM for the wild type. The Km (methionine) for S-adenosyl methionine synthetase was not altered.

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