Project description:Increasing numbers of small proteins with diverse physiological roles are being identified and characterized in both prokaryotic and eukaryotic systems, but the origins and evolution of these proteins remain unclear. Recent genomic sequence analyses in several organisms suggest that new functions encoded by small open reading frames (sORFs) may emerge de novo from noncoding sequences. However, experimental data demonstrating if and how randomly generated sORFs can confer beneficial effects to cells are limited. Here we show that by up-regulating hisB expression, de novo small proteins (≤ 50 amino acids in length) selected from random sequence libraries can rescue Escherichia coli cells that lack the conditionally essential SerB enzyme. The recovered small proteins are hydrophobic and confer their rescue effect by binding to the 5’ end regulatory region of the his operon mRNA, suggesting that protein binding promotes structural rearrangements of the RNA that allow increased hisB expression. This study adds RNA regulatory elements as another interacting partner for de novo proteins isolated from random sequence libraries, and provides further experimental evidence that small proteins with selective benefits can originate from the expression of nonfunctional sequences.
Project description:The noncoding genome plays an important role in de novo gene birth and the emergence of genetic novelty. Nevertheless, how the properties of noncoding sequences could promote the birth of novel genes and shape the structural diversity and evolution of proteins remains unclear. Here, we investigated the potential of the noncoding genome of yeast to produce novel protein bricks that can give rise to novel genes or be integrated in pre-existing proteins, thus participating in protein structure evolution and diversity. Combining different bioinformatics approaches, we showed that intergenic ORFs of yeast encompass the large structural diversity of canonical proteins with the majority encoding peptides predicted as foldable. Then, we investigated the early stages of de novo gene birth with Ribosome Profiling and systematic reconstruction of yeast de novo gene ancestral sequences. We highlighted sequence and structural factors determining de novo gene birth and protein evolution. Finally, we showed a strong correlation between the fold potential of de novo genes and their ancestral ORFs reflecting the relationship between the noncoding genome and the protein structure universe.
Project description:We describe a multiple de novo CNV (MdnCNV) phenomenon in which individuals with genomic disorders carry five to ten constitutional de novo CNVs. Five such families are studied, which consists of four trios and one singleton. Various array platforms are used to interogate these families to identify de novo CNVs.
