Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5590285 | Genomics, Proteomics & Bioinformatics | 2016 | 14 Pages |
Abstract
Protein size is an important biochemical feature since longer proteins can harbor more domains and therefore can display more biological functionalities than shorter proteins. We found remarkable differences in protein length, exon structure, and domain count among different phylogenetic lineages. While eukaryotic proteins have an average size of 472 amino acid residues (aa), average protein sizes in plant genomes are smaller than those of animals and fungi. Proteins unique to plants are â¼81Â aa shorter than plant proteins conserved among other eukaryotic lineages. The smaller average size of plant proteins could neither be explained by endosymbiosis nor subcellular compartmentation nor exon size, but rather due to exon number. Metazoan proteins are encoded on average by â¼10 exons of small size [â¼176 nucleotides (nt)]. Streptophyta have on average only â¼5.7 exons of medium size (â¼230Â nt). Multicellular species code for large proteins by increasing the exon number, while most unicellular organisms employ rather larger exons (>400Â nt). Among subcellular compartments, membrane proteins are the largest (â¼520Â aa), whereas the smallest proteins correspond to the gene ontology group of ribosome (â¼240Â aa). Plant genes are encoded by half the number of exons and also contain fewer domains than animal proteins on average. Interestingly, endosymbiotic proteins that migrated to the plant nucleus became larger than their cyanobacterial orthologs. We thus conclude that plants have proteins larger than bacteria but smaller than animals or fungi. Compared to the average of eukaryotic species, plants have â¼34% more but â¼20% smaller proteins. This suggests that photosynthetic organisms are unique and deserve therefore special attention with regard to the evolutionary forces acting on their genomes and proteomes.
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Genetics
Authors
Obed RamÃrez-Sánchez, Paulino Pérez-RodrÃguez, Luis Delaye, Axel Tiessen,