Lluch-Senar, Maria 1982-Delgado Blanco, JavierChen, Wei-HuaLloréns Rico, Verónica, 1989-O’Reilly, Francis J.Wodke, Judith A.H.Unal, E. BesrayYus, EvaMartínez, SiraNichols, Robert J.Ferrar, TonyVivancos Prellezo, AnaSchmeisky, ArneStülke, JörgNoort, Vera vanGavin, Anne-ClaudeBork, PeerSerrano Pubull, Luis, 1982-2015-11-162015-11-162015Lluch-Senar M, Delgado J, Chen WH, Lloréns-Rico V, O'Reilly FJ, Wodke JA et al. Defining a minimal cell: essentiality of small ORFs and ncRNAs in a genome-reduced bacterium. Molecular systems biology. 2015;11(1):780. DOI: 10.15252/msb.201455581744-4292http://hdl.handle.net/10230/25104Identifying all essential genomic components is critical for the assembly of minimal artificial life. In the genome-reduced bacterium Mycoplasma pneumoniae, we found that small ORFs (smORFs; < 100 residues), accounting for 10% of all ORFs, are the most frequently essential genomic components (53%), followed by conventional ORFs (49%). Essentiality of smORFs may be explained by their function as members of protein and/or DNA/RNA complexes. In larger proteins, essentiality applied to individual domains and not entire proteins, a notion we could confirm by expression of truncated domains. The fraction of essential non-coding RNAs (ncRNAs) non-overlapping with essential genes is 5% higher than of non-transcribed regions (0.9%), pointing to the important functions of the former. We found that the minimal essential genome is comprised of 33% (269,410 bp) of the M. pneumoniae genome. Our data highlight an unexpected hidden layer of smORFs with essential functions, as well as non-coding regions, thus changing the focus when aiming to define the minimal essential genome.application/pdfeng© 2015 The Authors. Published under the terms of the CC BY 4.0 license. This is an open access article under the terms of the Creative Commons Attribution 4.0 License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.RNA no missatgersInteraccions RNA-proteïnainfo:eu-repo/semantics/articlehttp://dx.doi.org/10.15252/msb.20145558Minimal genomeNon-coding RNAsSmall proteinsinfo:eu-repo/semantics/openAccess