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Function of your protein

, its function is to facilitate the cotranslational installation of the 22nd amino acid pyrrolysine. PylRS has emerged as a major route to install nonanonical amino acids into proteins in living cells. The organism that Pyrrolysine is from was identified in a subset of methanogenic archaea. Enzymes that are within this class lack the N-terminal tRNA binding domain that is widely conserved amongst PylRS enzymes, yet they remain active and orthogonal in bacteria and eukaryotes.

Biological relevance and broader implications

Pyrrolysine is important for the organism because it plays a unique role in the key step in the growth of methanogens by activating the methyl group of these substrates for transfer to a corrinoid cofactor. If for whatever reason the tRNA is defective, mistranslation will occur and the amino acid will be attached to the wrong tRNA and misplaced in the protein. Mistranslation can be toxic for bacteria and mammalian cells which could eventually lead to mutations in the organism.

Important amino acids

, A ligand is a small molecule, protein or ion that binds to the DNA double helix. Once it binds to the protein it has the ability to form complexes with other biomolecules in order to perform biological processes. The in this protein is YLY (2R)-2-AMINO-6-({[(2S,3R)-3-METHYLPYRROLIDIN-2-YL]CARBONYL}AMINO)HEXANOYL [(2S,3R,4R,5R)-5-(6-AMINO-9H-PURIN-9-YL)-3,4-DIHYDROXYTETRAHYDROFURAN-2-YL]METHYL HYDROGEN (R)-PHOSPHATE.

The Catalytic triad amino acids didn't appear on the crystal structure in Protein Data Bank.

Intermolecular forces involved in Pyrrolysine tRNA synthetase are Hydrogen bonding between (Pro 136 to Arg 167) or (Glu 169 to Glu 177).

According to the article, "12 residues that line the amino acid binding pocket and that are generally thought to influence the substrate specificity of PylRS"(pg.9). Most residues in the substrate binding pocket are strictly conserved, however there are 3 amino acids that are considerable and they are: Leucine, Cysteine and Methionine. The positions at which they are located in the enzyme are L309, C348, and M350.

Structural highlights

The secondary structure of a protein contains regions of amino acid chains that are stabilized by hydrogen bonds which create alpha-helix and beta-pleated sheets. For Pyrrolysine tRNA synthetase, the has 2 domains, one called the N-terminal and the other being the C-terminal. Pyrrolysine is a modified lysine with a 4-methylpyrroline-5-carboxylate group linked by an amide to the ɛ-amino group. Pyrrolysine is lysine in which has a pyrroline ring linked to the end of the lysine side chain.

The tertiary structure of a protein is the overall 3D structure of the protein. The protein is stabilized by outside polar hydrophilic hydrogen and ionic bond interactions, and internal hydrophobic interactions between non-polar amino acid side chains.

The quaternary structure of a protein is when several protein chains or subunits are packed altogether. Each of the protein chains or subunits have their own primary, secondary, and tertiary structure and are held together by van der Waals forces and hydrogen bonds between nonpolar side chains.

A space-filling view of a protein is a 3-dimensional model that gives a better picture of what the molecule would look and what the overall shape of the protein would be.

This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.

Other important features

Pyrrolysine tRNA synthetase is able to form a protein dimer. A protein dimer is a macromolecular complex formed by two protein monomers, or single proteins.

Larger structures are important to the proteins function because beginning from the primary structure, the unique sequence of amino acids dictate the 3D conformation the folded protein will have, which will then determine the function of the protein. The tertiary structure of a protein is the most important level because it determines the enzyme activity of a protein.

Another important feature of Pyrrolysine tRNA synthetase is that unlike other aminoacyl-tRNA synthetases that are commonly used for genetic code expansion, PylRS does not cross react with other tRNAs in both bacterial and eukaryotic hosts. This is important because the PylRS and tRNA pyl pair can be used to install ncAAs into proteins in a variety of model organisms. Secondly, PylRS has a remarkably high tolerance for structurally disparate ncAA substrates, which is attributed to the large size of the amino acid binding pocket within the enzyme's active site. Finally, unlike most aaRSs, PylRS does not interact with the codon of its cognate tRNA; therefore the anticodon can be mutated to recognize codons other than UAG without impacting tRNA recognition by PylRS.