Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: RNA editing

Sortuj według:

Ogranicz wyniki do:

Editing of plant mitochondrial transfer RNAs

100%

Fey J., Weil J. H., Tomita K., Cosset A., Dietrich A., Small I., Marechal-Drouard L.

Acta Biochimica Polonica

2001

tom 48

nr 2

Editing in plant mi to chon dria con sists in C to U changes and mainly af fects mes senger RNAs, thus pro vid ing the cor rect ge netic in for ma tion for the biosynthesis of mi to- chon drial (mt) pro teins. But ed it ing can also af fect some of the plant mt tRNAs encoded by the mt ge nome. In di cots, a C to U ed it ing event cor rects aC:A mis match into a U:A base-pair in the acceptor stem of mt tRNAPhe (GAA). In larch mitochondria, three C to U ed it ing events re store U: A base-pairs in the ac cep tor stem, D stem and anticodon stem, re spec tively, of mt tRNAHis (GUG). For both these mt tRNAs ed it ing of the pre cur sors is a pre req ui site for their pro cess ing into ma ture tRNAs. In po tato mt tRNACys (GCA), ed it ing con verts a C28:U42 mis match in the anticodon stem into a U28:U42 non-canonical base-pair, and reverse transcriptase minisequencing has shown that the mature mt tRNACys is fully edited. In the bryophyte Marchantia polymorpha this U res i due is en coded in the mt ge nome and evo lu tion ary stud ies sug gest that res to ra tion of the U28 res i due is nec es sary when it is not en coded in the gene. How ever, in vitro stud ies have shown that nei ther pro cess- ing of the pre cur sor nor amino acylation of tRNACys re quires C to U ed it ing at this po- si tion. But se quenc ing of the pu ri fied mt tRNACys has shown that Y is pres ent at po si tion 28, indicating that C to U editing is a prerequisite for the subsequent isomerization of U into Y at po si tion 28.

Regulatory mechanisms of gene expression: complexity with elements of deterministic chaos

84%

Jura J., Wegrzyn P., Jura J., Koj A.

Acta Biochimica Polonica

2006

tom 53

nr 1

Linear models based on proportionality between variables have been commonly applied in biology and medicine but in many cases they do not describe correctly the complex relationships of living organisms and now are being replaced by nonlinear theories of deterministic chaos. Recent advances in molecular biology and genome sequencing may lead to a simplistic view that all life processes in a cell, or in the whole organism, are strictly and in a linear fashion controlled by genes. In reality, the existing phenotype arises from a complex interaction of the genome and various environmental factors. Regulation of gene expression in the animal organism occurs at the level of epigenetic DNA modification, RNA transcription, mRNA translation, and many additional alterations of nascent proteins. The process of transcription is highly complicated and includes hundreds of transcription factors, enhancers and silencers, as well as various species of low molecular mass RNAs. In addition, alternative splicing or mRNA editing can generate a family of polypeptides from a single gene. Rearrangement of coding DNA sequences during somatic recombination is the source of great variability in the structure of immunoglobulins and some other proteins. The process of rearrangement of immunoglobulin genes, or such phenomena as parental imprinting of some genes, appear to occur in a random fashion. Therefore, it seems that the mechanism of genetic information flow from DNA to mature proteins does not fit the category of linear relationship based on simple reductionism or hard determinism but would be probably better described by nonlinear models, such as deterministic chaos.

Ograniczanie wyników

2 Acta Biochimica Polonica

1 Cosset A.

1 Dietrich A.

1 Fey J.

1 Jura J.

1 Koj A.

1 Marechal-Drouard L.

1 Small I.

1 Tomita K.

1 Wegrzyn P.

1 Weil J. H.

1 2006

1 2001

Wyniki wyszukiwania

Editing of plant mitochondrial transfer RNAs

Regulatory mechanisms of gene expression: complexity with elements of deterministic chaos