Translation initiation: variations in the mechanism can be anticipated

• Published in: Cellular and molecular life sciences : CMLS 2011-03, Vol.68 (6), p.991-1003
• Main Authors: Malys, Naglis, McCarthy, John E. G
• Format: Article
• Language: English
• Subjects: Archaea; Archaea - genetics; Archaea - physiology; Bacteria; Bacterial Physiological Phenomena; Biochemistry; Biological Evolution; Biomedical and Life Sciences; Biomedicine; Biosynthesis; Cell Biology; Eukarya; Eukaryota - genetics; Eukaryota - physiology; evolution; Evolutionary biology; Initiation factor; Life Sciences; messenger RNA; Models, Biological; Peptide Chain Initiation, Translational - physiology; Protein synthesis; Proteins; Review; Ribonucleic acid; Ribosome; Ribosome Subunits - metabolism; RNA; RNA, Messenger - metabolism; Translation initiation mechanism; Virology; Virus Physiological Phenomena; viruses
• ISSN: 1420-682X; 1420-9071
• DOI: 10.1007/s00018-010-0588-z

Translation initiation is a critical step in protein synthesis. Previously, two major mechanisms of initiation were considered as essential: prokaryotic, based on SD interaction; and eukaryotic, requiring cap structure and ribosomal scanning. Although discovered decades ago, cap-independent translation has recently been acknowledged as a widely spread mechanism in viruses, which may take place in some cellular mRNA translations. Moreover, it has become evident that translation can be initiated on the leaderless mRNA in all three domains of life. New findings demonstrate that other distinguishable types of initiation exist, including SD-independent in Bacteria and Archaea, and various modifications of 5′ end-dependent and internal initiation mechanisms in Eukarya. Since translation initiation has developed through the loss, acquisition, and modification of functional elements, all of which have been elevated by competition with viral translation in a large number of organisms of different complexity, more variation in initiation mechanisms can be anticipated.