AMINOACYL T-RNA SYNTHETASES

In the various aspects of molecular biology, the regulatory mechanism in the different organisations is controlled with the help of the various biochemicals that control metabolic action. Aminoacyl t-RNA synthetases (aaRS) is a type of enzyme that helps to ligate an amino acid to tRNA and convert it to aminoacyl tRNA. In order to complete the translation (protein synthesis from RNA), this enzyme plays an important role in the regulation. This enzyme creates covalent bonds by esterification between the amino acid and tRNA that can be observed in a universally distributed manner. 

Description of aminoacyl t-RNA synthetases

The enzyme aminoacyl tRNA synthetases (aaRS) have a multi-domain protein structure that plays a vital role in protein synthesis by inherently connecting the amino acids to the tRNA. There are known to be 24 families of aaRS and every molecule of the family presents a specific folding site that has the potential to bind with ATP, an amino acid binding site and 3′-terminus. The dual-substrate selectivity shows the potential way to attach with the amino acid and then with tRNA. Due to the ligating property of the enzyme, it is called the tRNA ligases that may have some other metabolic action as well. 

Functions of aminoacyl t-RNA synthetases 

The functions of aaRS are described as follows, 

• The decoration of the mRNA is regulated with the help of aaRS which are the specific amino acids that are attached corresponding to the codons. 

• This enzyme makes the regulatory process of translation continue in order to control various mechanisms in the cellular body. 

• The enzyme attaches the required and specific amino acid to tRNA with a covalently that has been created by esterification. 

• The enzyme chargers the tRNA to interact further in translation. 

• The enzyme manages to connect a new domain to novel functions in order to control the regulation in the cellular organisms. 

Classification of aminoacyl t-RNA synthetases 

There are nearly 23 known aaRS that can be divided into separate classes that have distinguished characteristics in the structure and eventually the differences can be seen in the section of the functions. There are two specific classes namely class I and class that have the distinguished structural variation. The structure of both of these classes are briefly discussed as follows, 

• Class I characteristics, this class of enzyme has a beta driven sheet that poses a dinucleotide feature surrounded with alpha-helices. The dinucleotide section of the enzyme contains the major HIGH and KMSKS that has been separated by a connective peptide (CP1). 

• Class II characteristics, this class has a slightly different structure than the class I structure and it is divided into several other classes. The structure of the class II enzyme is known to have seven stranded beta helices that are flanked with the alpha-helix structure showing a lesser degree of conversion than class I. 

Origin and evolution 

The origin of this enzyme is known to present from several time periods that this has been constructed and it has originated at the very beginning of the cellular forms. It is observed that the separate class of the enzyme originated from the separate way due to the differences of steric hindrances. The ancestor molecules of the different classes of aaRS may be different and have changed throughout the evolutionary period and have the potential to detect the structural differences of the molecule. It is observed that the activity of the enzymes is encoded with the variation of a specific gene and this is why it has the ability to attach itself to the targeted amino acid. The reduced version of aaRS has slightly more than 100 amino acids but still, this has the potential to attract and bind with the codons. 

t-RNA synthesis

t-RNA or transfer ribonucleic acid is synthesised from the tRNA gene by implementing the transcription process where RNA polymerase is the prime enzyme to initiate and continue the process. The transcription process takes place by undergoing stages of processing, fragment splicing, the addition of CCA and posttranscriptional modification. There are 5′ and 3′ extra sequences in the Primary transcripts of tRNA genes, which are excised from the fragment by specific nucleases as well as introns. Endonuclease is also a major factor associated with the process. The resultant fragments are ligated with enzyme ligase. In the tRNA template the CCA sequences are not encoded which are present at the 3’ end of mature tRNA and often added post-transcriptionally with the use of CCA-adding enzymes. Modified nucleotides generated by modification enzymes are found in all mature tRNA molecules and are thought to be involved in tRNA structural stabilisation, decoding properties, and correct processing. To maintain cellular functioning, the concentration of particular tRNA molecules is regulated.

Conclusion 

The aaRS is an enzyme that helps to regulate the major functions of the translation in universal cells. The enzyme can be divided into two distinguished versions that are different structurally. The various structural differences in the enzymes are discussed and the major functions of the cells have managed to make sure that the whole process of regulating the mechanism in the cellular organism is managed. The functions of the enzymes are described in a proper manner and the process of regulating the whole functions in the cells are described, even major management of the regulation.