Low-complexity sequences and single amino acid repeats: not just "junk" peptide sequences
Wilfried Haerty1, G Brian Golding
1Biology Department, McMaster University, Hamilton, ON, Canada.
Genome
|October 22, 2010
Summary
Previously, unstructured peptides were deemed nonfunctional. However, rapidly evolving low-complexity sequences, common in eukaryotes, are now understood to be shaped by selection, not just neutral drift.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Bioinformatics
Background:
- The traditional view linked protein structure directly to function, considering unstructured peptides as non-functional and evolving neutrally.
- This paradigm overlooked the prevalence and potential importance of intrinsically disordered regions (IDRs) or intrinsically disordered proteins (IDPs).
Purpose of the Study:
- To challenge the long-held notion that unstructured peptides are nonfunctional.
- To review evidence suggesting that rapidly evolving low-complexity sequences are under selection pressure.
- To highlight the functional significance of these sequences in eukaryotic proteomes.
Main Methods:
- Literature review of studies on protein structure-function relationships.
- Analysis of comparative genomics data on shared peptides across eukaryotic proteomes.
- Examination of evolutionary dynamics and selective pressures on low-complexity sequences.
Main Results:
- Low-complexity sequences, often lacking stable structures, are surprisingly common across eukaryotic proteomes.
- These sequences exhibit rapid evolution and variations in size can have significant functional consequences.
- Evidence suggests these sequences are not neutral "junk" but are actively shaped by evolutionary selection.
Conclusions:
- The "lock and key" model is insufficient for understanding all protein functions.
- Low-complexity sequences represent an important class of functional peptides that evolve under selection.
- Re-evaluation of protein evolution must incorporate the role of intrinsically disordered regions.
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