Abstract:Small open reading frames (sORFs) are ubiquitous in the genomes of living organisms, which are generally not fully annotated and studied due to their short length and difficulty in detection of their encoded small proteins (also termed microproteins or miniproteins). With the advancement of high-throughput sequencing, translatomics and mass spectrometry, increasing sORFs have been identified in different living organisms. At the same time, specific bioinformatic tools have also contribute to the mining of sORFs. Small proteins encoded by sORFs as well as translational regulation mediated by sORFs have been applied in medicinal development and exploration of mechanisms underlying plant disease resistance. However, the studies and applications of sORFs in microorganisms remain limited. This review summarizes the latest progress in the identification of small proteins encoded by sORFs, the annotation of upstream open reading frames (uORFs), as well as uORF-mediated regulation on mRNA translation. In particular, we reviewed the identification and functional analysis of sORFs in microbial genomes, especially budding yeast and filamentous fungi. This review provides a basis for understanding the function and mechanism of sORFs, as well as studies on microproteins and translation regulation in other organisms including plans and animals.
