Pentatricopeptide repeat explained

The pentatricopeptide repeat (PPR) is a 35-amino acid sequence motif. Pentatricopeptide-repeat-containing proteins are a family of proteins commonly found in the plant kingdom. They are distinguished by the presence of tandem degenerate PPR motifs[1] and by the relative lack of introns in the genes coding for them.

Approximately 450 such proteins have been identified in the Arabidopsis genome, and another 477 in the rice genome.[2] Despite the large size of the protein family, genetic data suggest that there is little or no redundancy of function between the PPR proteins in Arabidopsis.

The purpose of PPR proteins is currently under dispute. It has been shown that a good deal of those in Arabidopsis interact (often essentially) with mitochondria and other organelles[3] and that they are possibly involved in RNA editing.[4] However many trans proteins are required for this editing to occur and research continues to look at which proteins are needed.[5]

The structure of the PPR has been resolved. It folds into a helix-turn-helix structure similar to those found in the tetratricopeptide repeat. Several repeats of the protein forms a ring around a single-strand RNA molecule in a sequence-sensitive way reminiscent of TAL effectors.[6]

Examples

Human genes encoding proteins containing this repeat include:

Notes and References

  1. Mingler MK, Hingst AM, Clement SL, Yu LE, Reifur L, Koslowsky DJ . Identification of pentatricopeptide repeat proteins in Trypanosoma brucei . Mol. Biochem. Parasitol. . 150 . 1 . 37–45 . November 2006 . 16837079 . 10.1016/j.molbiopara.2006.06.006 .
  2. O'Toole N, Hattori M, Andres C, Iida K, Lurin C, Schmitz-Linneweber C, Sugita M, Small I . On the expansion of the pentatricopeptide repeat gene family in plants . Mol. Biol. Evol. . 25 . 6 . 1120–8 . June 2008 . 18343892 . 10.1093/molbev/msn057 . free .
  3. Lurin C, Andrés C, Aubourg S, Bellaoui M, Bitton F, Bruyère C, Caboche M, Debast C, Gualberto J, Hoffmann B, Lecharny A, Le Ret M, Martin-Magniette ML, Mireau H, Peeters N, Renou JP, Szurek B, Taconnat L, Small I . Genome-wide analysis of Arabidopsis pentatricopeptide repeat proteins reveals their essential role in organelle biogenesis . Plant Cell . 16 . 8 . 2089–103 . August 2004 . 15269332 . 519200 . 10.1105/tpc.104.022236 .
  4. Kotera E, Tasaka M, Shikanai T . A pentatricopeptide repeat protein is essential for RNA editing in chloroplasts . Nature . 433 . 7023 . 326–30 . January 2005 . 15662426 . 10.1038/nature03229 . 2005Natur.433..326K . 4416316 .
  5. Takenaka M, Verbitskiy D, Zehrmann A, Brennicke A . Reverse genetic screening identifies five E-class PPR-proteins involved in RNA editing in mitochondria of Arabidopsis Thaliana . J Biol Chem . 285. 35. 27122–27129. June 2010 . 20566637 . 10.1074/jbc.M110.128611 . free . 2930711 .
  6. Yin P, Li Q, Yan C, Liu Y, Liu J, Yu F, Wang Z, Long J, He J, Wang HW, Wang J, Zhu JK, Shi Y, Yan N . 6 . Structural basis for the modular recognition of single-stranded RNA by PPR proteins . Nature . 504 . 7478 . 168–71 . December 2013 . 24162847 . 10.1038/nature12651 . 2013Natur.504..168Y . 4471801 .

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