Essential functions linked with structural disorder in organisms of minimal genome.
Intrinsically disordered regions (IDRs) of proteins fulfill important regulatory roles in most organisms. However, the proteins of certain endosymbiont and intracellular pathogenic bacteria with extremely reduced genomes contain disproportionately small amounts of IDRs, consisting almost entirely of folded domains. As their genomes co-evolving with their hosts have been reduced in unrelated lineages, the proteomes of these bacteria represent independently evolved minimal protein sets. We systematically analyzed structural disorder in a representative set of such minimal organisms to see which types of functionally relevant longer IDRs are invariably retained in them. We found that a few characteristic functions are consistently linked with conformational disorder: ribosomal proteins, key components of the protein production machinery, a central coordinator of DNA metabolism and certain housekeeping chaperones seem to strictly rely on structural disorder even in genome-reduced organisms. We propose that these functions correspond to the most essential and probably also the most ancient ones fulfilled by structural disorder in cellular organisms.



This article was reviewed by Michael Gromiha, Zoltan Gaspari and Sandor Pongor.
Structural Biology Research Center (SBRC), Flanders Institute for Biotechnology (VIB), Vrije Universiteit Brussel (VUB), 1050 Pleinlaan 2, Brussels, Belgium.
Rita
R
Pancsa
Structural Biology Research Center (SBRC), Flanders Institute for Biotechnology (VIB), Vrije Universiteit Brussel (VUB), 1050 Pleinlaan 2, Brussels, Belgium. ptompa@vub.ac.be.|Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1117 Budapest, Magyar Tudósok körútja 2., Budapest, Hungary. ptompa@vub.ac.be.
Peter
P
Tompa
D000595:Amino Acid Sequence; D001419:Bacteria / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D016680:Genome, Bacterial; D020543:Proteome
D001426:Bacterial Proteins; D020543:Proteome
Chaperone function; Disorder prediction; Endosymbiont; Essential function; Genome reduction; Genome-reduced bacterium; Intrinsically disordered; Minimal genome; Structural disorder