- ID: EG10586
- Name: metG
- Organism: E. coli
- UniProt ID: P00959
- Description: The metG gene encodes the Methionine—tRNA ligase enzyme which belongs to a family of aminoacyl tRNA synthases (catalyze the linking of molecules). ATP hydrolysis drives these synthases to link amino acids to their corresponding tRNA molecules by interpreting the mRNA. This enzyme, specifically, facilitates the reaction that couples methionine to methionyl-tRNA in the tRNA charging pathway, which groups E. coli tRNA charging reactions (reactions that load tRNA with the amino acid). It is essential for the initiation of mRNA translation and for the elongation of protein synthesis.  
- DNA Length: 2,034 base pairs.
- DNA sequence:
ATG ACA CAG GTC GCG AAG AAG ATC CTT GTA ACT TGT GCA CTT CCT TAC GCA AAT GGA TCA ATT CAC CTG GGA CAT ATG CTTGAA CAC ATT CAG GCC GAC GTC TGG GTG CGT TAC CAA CGC ATG CGT GGA CAC GAG GTC AAC TTC ATT TGT GCG GAT GAT GCCCAC GGA ACA CCA ATT ATG CTG AAA GCG CAA CAG TTA GGT ATT ACG CCT GAA CAG ATG ATC GGC GAA ATG TCA CAA GAG CACCAG ACC GAT TTC GCG GGC TTT AAT ATC TCG TAC GAT AAC TAT CAC TCT ACA CAT TCA GAA GAG AAC CGT CAA CTG AGT GAGTTA ATT TAT TCA CGT TTG AAG GAG AAC GGG TTC ATT AAA AAT CGC ACT ATT TCA CAA TTA TAT GAT CCC GAA AAA GGT ATGTTC CTG CCT GAC CGT TTC GTG AAA GGA ACC TGT CCG AAG TGT AAA TCC CCC GAT CAA TAT GGT GAC AAT TGT GAA GTT TGCGGT GCG ACG TAT TCG CCA ACG GAA TTG ATC GAA CCC AAG AGC GTA GTC TCA GGC GCC ACC CCA GTG ATG CGC GAT TCG GAACAC TTC TTT TTC GAT TTG CCT TCC TTC AGC GAA ATG TTA CAG GCC TGG ACC CGC TCA GGT GCG TTG CAG GAA CAA GTA GCGAAT AAA ATG CAG GAG TGG TTT GAA TCA GGT CTG CAA CAG TGG GAT ATT AGT CGC GAC GCT CCC TAT TTC GGC TTC GAG ATCCCG AAC GCT CCG GGC AAG TAT TTC TAC GTG TGG CTG GAC GCG CCC ATC GGT TAT ATG GGC TCC TTC AAA AAT CTT TGT GATAAA CGC GGA GAC TCT GTG TCC TTT GAT GAG TAT TGG AAA AAG GAC AGT ACA GCT GAA CTG TAC CAT TTT ATT GGG AAA GACATT GTG TAC TTT CAT TCG TTG TTT TGG CCC GCC ATG CTT GAG GGA TCT AAC TTT CGC AAG CCT TCA AAC TTA TTC GTA CACGGC TAC GTA ACG GTA AAT GGA GCT AAA ATG TCG AAG TCC CGT GGT ACC TTC ATC AAG GCG AGT ACC TGG CTG AAT CAC TTTGAT GCA GAC TCA TTG CGC TAT TAT TAT ACG GCC AAA TTA TCG AGT CGC ATC GAT GAC ATT GAT CTT AAC TTA GAG GAC TTCGTG CAG CGC GTA AAC GCG GAT ATT GTT AAC AAG GTC GTT AAC TTG GCG TCT CGC AAC GCA GGG TTC ATC AAT AAG CGC TTCGAT GGT GTT TTG GCA TCT GAG TTA GCC GAC CCA CAA TTA TAC AAG ACG TTT ACT GAT GCG GCT GAA GTA ATC GGG GAA GCCTGG GAA TCG CGT GAG TTT GGT AAA GCG GTA CGT GAA ATC ATG GCG TTA GCG GAT TTG GCT AAT CGT TAC GTC GAT GAG CAGGCA CCC TGG GTA GTC GCC AAA CAA GAG GGC CGC GAC GCT GAC CTT CAA GCC ATC TGT TCA ATG GGA ATT AAT TTA TTT CGCGTA CTT ATG ACA TAT TTA AAG CCC GTT TTG CCG AAA CTT ACT GAA CGC GCG GAG GCC TTC CTG AAT ACC GAA CTG ACT TGGGAT GGG ATC CAA CAG CCT CTT TTG GGG CAT AAA GTG AAC CCG TTT AAG GCC TTA TAT AAT CGT ATT GAC ATG CGC CAG GTCGAA GCG CTT GTC GAG GCT TCG AAA GAG GAG GTA AAG GCA GCT GCT GCC CCC GTA ACT GGC CCT CTT GCG GAC GAC CCA ATCCAG GAA ACG ATC ACT TTT GAC GAC TTT GCG AAG GTC GAT CTG CGT GTT GCT TTA ATC GAG AAC GCG GAG TTC GTG GAA GGCAGC GAT AAA CTT TTG CGC CTG ACC TTA GAT CTT GGT GGT GAG AAA CGC AAC GTG TTT TCA GGG ATC CGT AGC GCC TAT CCAGAC CCG CAG GCA TTG ATT GGT CGT CAT ACG ATT ATG GTT GCG AAC TTA GCT CCG CGC AAA ATG CGT TTC GGT ATC TCT GAAGGC ATG GTC ATG GCA GCC GGT CCA GGG GGG AAG GAT ATT TTC CTG CTT AGC CCG GAT GCT GGT GCA AAA CCA GGC CAT CAAGTC AAG TAA
- Amino Acid length: 677 amino acids.
- Amino Acid sequence:
Function and Homologs
- Functional Category: Translation.
- Product: Methionine—tRNA ligase
- Module: Methionyl-tRNA aminoacylation
- Closest homologous proteins: The top (max three) homologous proteins to this protein, as identified by BLAST searches.
- Equivalent JCVI functional protein: MMSYN1_0012_sflamen.
- Expression Level: High-2572 protein copies/cell (source: E. Coli Proteome Dataset)
- Expression Level Hypothesis: This gene should be expressed at a high level because of its important role in interpreting the DNA code by linking amino acids to the appropriate tRNAs. It is also relevant to note that research shows that expression levels are enhanced in different strains of E. coli and that this level is coupled to the growth rate . Methionine is also used relatively frequently in E. Coli , and perhaps can explain why metG is expressed at a higher level in E. Coli than in mycoides. 
- Expression Level References and Description: I found expression level information for this exact gene in the E. coli dataset and the description of the gene's function here: . Given that this dataset encapsulates measured levels of all expressed proteins under different growth conditions, I believe this expression level is accurate.
- Expression Time: Right at the beginning
- Expression Level Hypothesis: Because this gene encodes methionyl-tRNA synthase which is essential for the initiation of mRNA translation and elongation of protein synthesis, this gene is directly involved in the central dogma of biology and thus must be expressed right at the beginning. Specifically, this enzyme catalyzes the reaction that couples methionine to methionyl-tRNA; because methionine is a start codon, it is especially important that metG is expressed at the beginning. 
- Expression Time References and Description: As stated in the hypothesis, this gene should be expressed at the beginning because it is needed for translation—part of the central dogma—which must happen right away. I used information about the gene's function that I found here: .
- Other Components: This enzyme acts independently to link an amino acid to its corresponding tRNA molecule (single subunit); no other components are required for this catalyst to work. Mg2+ and Zn2+ are cofactors of this enzyme, though . Although this is not a component, here is a link to another tRNA synthase EG10552.
- Possible Dependencies: Methionine biosynthesis because methionine—tRNA ligase has no purpose without methionine.
- Process: Coupling methionine to methionyl-tRNA 
- Inputs: initiator tRNA(Met), L-methionine, ATP
- Outputs: L-methionyl-[initiator tRNA(Met)], AMP, diphosphate
- Synthesis Score: The synthesis score of your construct: 1, 2,3
- Predicted Translation Rate: Prediction of construct translation rate from the RBS calculator
- Design Notes and Details: For example, had to use a rare codon to fix folding energy;
- GenBank File: A link to the GenBank file. file