title: How Common Is Disorder? Occurrence of Disordered Residues in Four Domains of Life.
abstract: Disordered regions play important roles in protein adaptation to challenging environmental conditions. Flexible and disordered residues have the highest propensities to alter the protein packing. Therefore, identification of disordered/flexible regions is important for structural and functional analysis of proteins. We used the IsUnstruct program to predict the ordered or disordered status of residues in 122 proteomes, including 97 eukaryotic and 25 large bacterial proteomes larger than 2,500,000 residues. We found that bacterial and eukaryotic proteomes contain comparable fraction of disordered residues, which was 0.31 in the bacterial and 0.38 in the eukaryotic proteomes. Additional analysis of the total of 1540 bacterial proteomes of various sizes yielded a smaller fraction of disordered residues, which was only 0.26. Together, the results showed that the larger is the size of the proteome, the larger is the fraction of the disordered residues. A continuous dependence of the fraction of disordered residues on the size of the proteome is observed for four domains of life: Eukaryota, Bacteria, Archaea, and Viruses. Furthermore, our analysis of 122 proteomes showed that the fraction of disordered residues increased with increasing the length of homo-repeats for polar, charged, and small residues, and decreased for hydrophobic residues. The maximal fraction of disordered residues was obtained for proteins containing lysine and arginine homo-repeats. The minimal fraction was found in valine and leucine homo-repeats. For 15-residue long homo-repeats these values were 0.2 (for Val and Leu) and 0.7 (for Lys and Arg).
authors: Institute of Protein Research, Russian Academy of Sciences, Pushchino 142290, Moscow Region, Russia. mlobanov@phys.protres.ru.
authors: Mikhail Yu
authors: MY
authors: Lobanov
authors: Institute of Protein Research, Russian Academy of Sciences, Pushchino 142290, Moscow Region, Russia. ogalzit@vega.protres.ru.
authors: Oxana V
authors: OV
authors: Galzitskaya
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D030562:Databases, Protein; D023281:Genomics / Q000379:methods*; D006801:Humans; D064267:Intrinsically Disordered Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry*; D020543:Proteome / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D064267:Intrinsically Disordered Proteins; D011506:Proteins; D020543:Proteome
keywords: computational prediction; disordered regions; homo-repeats; proteome