Schmitz JF, Ullrich K, Bornberg-Bauer E
De Novo Genes are "Frozen Accidents" which Escaped Rapid Turnover of Pervasively Transcribed ORFs
, 2017

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A recent surge of studies suggested that many novel genes arise <i>de novo</i> from previously non-coding
DNA and not by duplication. However, since most studies concentrated on longer evolutionary time
scales and rarely considered protein structural properties, it remains unclear how these properties
are shaped by evolution, depend on genetic mechanisms and influence gene survival. Here we
compare open reading frames (ORFs) from high coverage transcriptomes from mouse and another four
mammals covering 160 million years of evolution. We find that novel ORFs pervasively emerge from
intergenic and intronic regions but are rapidly lost again while relatively fewer arise from duplications
but are retained over much longer times. Surprisingly, disorder and other protein properties of young
ORFs do not change with gene age. Only length and nucleotide composition change, probably to
avoid aggregation. Thus de novo genes resemble frozen accidents of randomly emerged ORFs which
survived initial purging, likely because they are functional.