Utilisateur:Jlcrbm/Brouillon
An array of tandem repeats is defined as several (at least two) adjacent copies having the same or similar sequence motifs. These periodic sequences are generated by internal duplications in both coding and noncoding genomic sequences. Repetitive units of protein tandem repeats are considerably diverse,ranging from the repetition of a single amino acid to domains of 100 or more residues. [1]
Distribution in proteomes
modifierTandem repeats are ubiquitous in proteomes and occur in at least 14% of all proteins.[2] For example, they are present in almost every third human protein and even in every second protein from Plasmodium falciparum or Dictyostelium discoideum.[2][3] Tandem repeats with short repetitive units (especially homorepeats) are more frequent than others.[2]
Structure of tandem repeats
modifierApproximately half of the TR regions has intrinsically disordered conformation being naturally unfolded.[4][5][6] The other half of the regions with the stable 3D structure has a plethora of shapes and functions.[7][8] Depending on the length of the repetitive units, their protein structures can be subdivided into five classes: (i) crystalline aggregates formed by regions with 1 or 2 residue long repeats, (ii) fibrous structures stabilized by interchain interactions with 3-7 residue repeats, (iii) structures with the repeats of 5–40 residues dominated by solenoid proteins, (iv) ‘‘closed’’ (not elongated) structures with the repeats of 30-60 residue long and, finally, (v) ‘‘beads on a string’’ structures with typical size of repeats over 50 residues, which are already large enough to fold independently into stable domains.[7]
Functions of proteins with tandem repeats
modifierSome well-known examples of proteins with tandem repeats are collagen, which plays a key role in the arrangement of the extracellular matrix; alpha-helical coiled coils having structural and oligomerization functions; leucine-rich repeat proteins, which specifically bind a number of globular proteins by their concave surfaces; and zinc-finger proteins, which regulate the expression of genes by binding DNA.
Evolution of tandem repeats
modifierReferences
modifier- Jaap Heringa, « Detection of internal repeats: how common are they? », Current Opinion in Structural Biology, vol. 8, no 3, , p. 338–345 (ISSN 0959-440X, DOI 10.1016/s0959-440x(98)80068-7, lire en ligne, consulté le )
- Edward M. Marcotte, Matteo Pellegrini, Todd O. Yeates et David Eisenberg, « A census of protein repeats », Journal of Molecular Biology, vol. 293, no 1, , p. 151–160 (ISSN 0022-2836, DOI 10.1006/jmbi.1999.3136, lire en ligne, consulté le )
- (en) Marco Pellegrini, « Tandem Repeats in Proteins: Prediction Algorithms and Biological Role », Frontiers in Bioengineering and Biotechnology, vol. 3, (ISSN 2296-4185, PMID 26442257, PMCID PMC4585158, DOI 10.3389/fbioe.2015.00143, lire en ligne, consulté le )
- Peter Tompa, « Intrinsically unstructured proteins evolve by repeat expansion », BioEssays, vol. 25, no 9, , p. 847–855 (ISSN 0265-9247 et 1521-1878, DOI 10.1002/bies.10324, lire en ligne, consulté le )
- Michelle Simon et John M Hancock, « Tandem and cryptic amino acid repeats accumulate in disordered regions of proteins », Genome Biology, vol. 10, no 6, , R59 (ISSN 1465-6906, DOI 10.1186/gb-2009-10-6-r59, lire en ligne, consulté le )
- Julien Jorda, Bin Xue, Vladimir N. Uversky et Andrey V. Kajava, « Protein tandem repeats - the more perfect, the less structured », FEBS Journal, vol. 277, no 12, , p. 2673–2682 (ISSN 1742-464X, DOI 10.1111/j.1742-4658.2010.07684.x, lire en ligne, consulté le )
- Andrey V. Kajava, « Tandem repeats in proteins: From sequence to structure », Journal of Structural Biology, vol. 179, no 3, , p. 279–288 (ISSN 1047-8477, DOI 10.1016/j.jsb.2011.08.009, lire en ligne, consulté le )