Global pentapeptide statistics are far away from expected distributions

Jarosław Poznański, Jan Topiński, Anna Muszewska, Konrad J. Dębski, Marta Hoffman-Sommer, Krzysztof Pawłowski, Marcin Grynberg

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The relationships between polypeptide composition, sequence, structure and function have been puzzling biologists ever since first protein sequences were determined. Here, we study the statistics of occurrence of all possible pentapeptide sequences in known proteins. To compensate for the non-uniform distribution of individual amino acid residues in protein sequences, we investigate separately all possible permutations of every given amino acid composition. For the majority of permutation groups we find that pentapeptide occurrences deviate strongly from the expected binomial distributions, and that the observed distributions are also characterized by high numbers of outlier sequences. An analysis of identified outliers shows they often contain known motifs and rare amino acids, suggesting that they represent important functional elements. We further compare the pentapeptide composition of regions known to correspond to protein domains with that of non-domain regions. We find that a substantial number of pentapeptides is clearly strongly favored in protein domains. Finally, we show that over-represented pentapeptides are significantly related to known functional motifs and to predicted ancient structural peptides.

Original languageEnglish (US)
Article number15178
JournalScientific reports
Volume8
Issue number1
DOIs
StatePublished - Dec 1 2018
Externally publishedYes

ASJC Scopus subject areas

  • General

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