A New UAG-Encoded Residue in the Structure of a Methanogen Methyltransferase

  title={A New UAG-Encoded Residue in the Structure of a Methanogen Methyltransferase},
  author={Bing Hao and Weimin Gong and Tsuneo K Ferguson and Carey M. James and Joseph Adrian Krzycki and Michael K. Chan},
  pages={1462 - 1466}
Genes encoding methanogenic methylamine methyltransferases all contain an in-frame amber (UAG) codon that is read through during translation. We have identified the UAG-encoded residue in a 1.55 angstrom resolution structure of the Methanosarcina barkerimonomethylamine methyltransferase (MtmB). This structure reveals a homohexamer comprised of individual subunits with a TIM barrel fold. The electron density for the UAG-encoded residue is distinct from any of the 21 natural amino acids. Instead… 

Translation of the amber codon in methylamine methyltransferase genes of a methanogenic archaeon

Members of the Methanosarcinaceae family can in addition to hydrogen/carbon dioxide utilize several methylated compounds and convert them to methane and appear to have a unique mechanism for amber codon readthrough.

The Residue Mass of L-Pyrrolysine in Three Distinct Methylamine Methyltransferases*

Successful mass spectral characterization of naturally occurring pyrrolysine and the first demonstration of the amber-encoded residue in proteins other than MtmB are reported and suggests that MtbB and MttB may exploit the unusual electrophilicity of pyr rolysine during catalysis.

Functional context, biosynthesis, and genetic encoding of pyrrolysine.

Crystal structure of methylornithine synthase (PylB): insights into the pyrrolysine biosynthesis.

A sophisticated bioinformatics strategy has shown a set of five genes (pylBCDST) to be both necessary and sufficient for the biosynthesis and utilization of pyrrolysine, the 22nd amino acid encoded by the natural genetic code.

Characterization of a Methanosarcina acetivorans mutant unable to translate UAG as pyrrolysine

The phenotype of ΔppylT reveals the deficiency in methylamine metabolism expected of a Methanosarcina species unable to decode UAG codons as pyrrolysine, but also indicates that loss of pylT does not compromise growth on other substrates.

Hidden in Plain Sight: The Biosynthetic Source of Pyrrolysine Revealed

  • T. FeknerM. Chan
  • Chemistry, Biology
    Chembiochem : a European journal of chemical biology
  • 2011
An important clue as to the true identity of this elusive metabolite came from the observation that by exogenously supplying d-ornithine, but not amino acids 2–4, it was possible to significantly increase the level of the PylRS–tRNA-mediated UAG suppression in E. coli transformed with pylTSBCD.

Biosynthesis and charging of pyrrolysine, the 22nd genetically encoded amino acid.

It is found that this unprecedented lysine homologue is incorporated into several methyltransferases from archaebacteria, for example monomethylamine methyltransferase (MtmB; Figure 1) from Krzycki and colleagues.

Structure and reaction mechanism of pyrrolysine synthase (PylD).

The structural investigation and implementation on the reaction mechanism of the enzymes required for the biosynthesis of pyrrolysine are described and may open novel opportunities for the harnessing of the system for biotechnology purposes.



Pyrrolysine Encoded by UAG in Archaea: Charging of a UAG-Decoding Specialized tRNA

Results indicate that pyrrolysine is the 22nd genetically encoded natural amino acid to be encoded by the UAG codon in methylamine methyltransferase genes of Methanosarcina barkeri.

The Amber Codon in the Gene Encoding the Monomethylamine Methyltransferase Isolated from Methanosarcina barkeri Is Translated as a Sense Codon*

The amber codon is thus read through during translation at apparently high efficiency and corresponds to lysine in tryptic fragments of MtmB even though canonical lysinesine codon usage is encountered in otherMethanosarcina genes.

Clustered Genes Encoding the Methyltransferases of Methanogenesis from Monomethylamine

A mechanism that circumvents UAG-directed termination of translation must operate during expression of mtmB in this methanogen, as well as in methionine synthase.

The Trimethylamine Methyltransferase Gene and Multiple Dimethylamine Methyltransferase Genes of Methanosarcina barkeri Contain In-Frame and Read-Through Amber Codons

Results indicate that the genes encoding the three types of methyltransferases that initiate methanogenesis from methylamine contain in-frame amber codons that are suppressed during expression of the characterized methyl transferases.

How a protein binds B12: A 3.0 A X-ray structure of B12-binding domains of methionine synthase.

The crystal structure of a 27-kilodalton methylcobalamin-containing fragment of methionine synthase from Escherichia coli was determined at 3.0 A resolution, revealing that the cobalt ligand, His759, and the neighboring residues Asp757 and Ser810, may form a catalytic quartet that modulates the reactivity of the B12 prosthetic group in methionines synthase.

Selenocysteine: the 21st amino acid

The aim of this article is to review the events leading to the elucidation of selenocysteine as being the 21st amino acid.

Reconstitution of Monomethylamine:Coenzyme M Methyl Transfer with a Corrinoid Protein and Two Methyltransferases Purified fromMethanosarcina barkeri *

Results show that MMCP is the major corrinoid protein for methanogenesis from monomethylamine detectable in extracts and that it interacts with two methyltransferases.