ABSTRACT
The tRNA structure contains conserved modifications that are responsible for its stability and are involved in the initiation and accuracy of the translation process. tRNA modification enzymes are prevalent in bacteria, archaea, and eukaryotes. tRNA Gm18 methyltransferase (TrmH) and tRNA m1G37 methyltransferase (TrmD) are prevalent and essential enzymes in bacterial populations. TrmH involves itself in methylation process at the 2'-OH group of ribose at the 18th position of guanosine (G) in tRNAs. TrmD methylates the G residue next to the anticodon in selected tRNA subsets. Initially, m1G37 modification was reported to take place on three conserved tRNA subsets (tRNA(Arg), tRNA(Leu), tRNA(Pro)); later on, few archaea and eukaryotes organisms revealed that other tRNAs also have the m1G37 modification. The present study reveals Gm18, m1G37 modification, and positions of m1G that take place next to the anticodon in tRNA sequences. We selected extremophile organisms and attempted to retrieve the m1G and Gm18 modification bases in tRNA sequences. Results showed that the Gm18 modification G residue occurs in all tRNA subsets except three tRNAs (tRNA(Met), tRNA(Pro), tRNA(Val)). Whereas the m1G37 modification base G is formed only on tRNA(Arg), tRNA(Leu), tRNA(Pro), and tRNA(His), the rest of the tRNAs contain adenine (A) next to the anticodon. Thus, we hypothesize that Gm18 modification and m1G modification occur irrespective of a G residue in tRNAs.
Subject(s)
Adenine , Anticodon , Archaea , Bacteria , Eukaryota , Guanosine , Methylation , Ribose , RNA, Transfer , RNA, Transfer, Arg , RNA, Transfer, His , RNA, Transfer, Leu , RNA, Transfer, ProABSTRACT
El presente trabajo presenta un nuevo espacio de configuración de codones fundado en el carácter dual que las bases poseen considerando dos propiedades fisicoquímicas esenciales: (a) especie química (Y o R) y (b) número de puentes de H (3 ó 2) involucrados en la interacción codón-anticodón. La concepción de esta nueva representación de codones se basa en la construcción de un espacio" bidimensional definido por dos ejes ortogonales cuyos "valores" quedan definidos por las ocho combinatorias posibles de las propiedades Y y R para uno de los ejes y por las ocho combinatorias posibles de las propiedades 2 y 3 para el otro eje...En este trabajo se presentan, discuten contribuciones a la teoría y utilidades prácticas
Subject(s)
Humans , Anticodon , Antigens, CD/genetics , DNA Transposable Elements , Genetic CodeABSTRACT
The Crick wobble hypothesis attributes the phenomenon of codon degeneracy to a certain impreciseness of pairing between the third base of the codon and the first base of the anticodon. This theoretical study investigates the pairing properties of some wobble bases, including both, observed and unobserved pairs. Some wobble base-pairs are predicted to follow the Watson-Crick pairs in configuration and pairing facility, while others deviate from this norm. The observed U:V pair is unique in that a pairing configuration may be suggested for it wherein the hydrogen-bonding involves the exocyclic 5-carboxymethoxy group of V. By comparing the theoretical data on the configurations of these pairs with the evidence for their existence/non-existence in nature, some guidelines emerge for differentiating between observed and unobserved base pairs on the basis of the pairing configuration.
Subject(s)
Adenine/chemistry , Anticodon , Base Pairing , Codon , Computer Simulation , Cytosine/chemistry , DNA/chemistry , Guanine/chemistry , Hydrogen Bonding , Inosine/chemistry , Models, Chemical , Nitrogen/chemistry , Nucleic Acid Conformation , Uracil/chemistryABSTRACT
The probability of randomly synthesized peptides having an excess of a given residue Ri (nRi>N/2; N = size of the peptide) decreases strongly with peptide size. For a strong, specific interaction of a Ri, rich peptide with a given sequence of a ribotide chain, peptides should be reasonably large. We discuss how a compromise can be achieved that may have had an important role on the origin of the genetic code.