title: Regulation of translation of the head protein of T4 bacteriophage by specific binding of EF-Tu to a leader sequence.
abstract: Recent evidence indicates that translation elongation factor Tu (EF-Tu) has a role in the cell in addition to its well established role in translation. The translation factor binds to a specific region called the Gol region close to the N terminus of the T4 bacteriophage major head protein as the head protein emerges from the ribosome. This binding was discovered because EF-Tu bound to Gol peptide is the specific substrate of the Lit protease that cleaves the EF-Tu between amino acid residues Gly59 and lle60, blocking phage development. These experiments raised the question of why the Gol region of the incipient head protein binds to EF-Tu, as binding to incipient proteins is not expected from the canonical role of EF-Tu. Here, we use gol-lacZ translational fusions to show that cleavage of EF-Tu in the complex with Gol peptide can block translation of a lacZ reporter gene fused translationally downstream of the Gol peptide that activated the cleavage. We propose a model to explain how binding of EF-Tu to the emerging Gol peptide could cause translation to pause temporarily and allow time for the leader polypeptide to bind to the GroEL chaperonin before translation continues, allowing cotranslation of the head protein with its insertion into the GroEL chaperonin chamber, and preventing premature synthesis and precipitation of the head protein. Cleavage of EF-Tu in the complex would block translation of the head protein and therefore development of the infecting phage. Experiments are presented that confirm two predictions of this model. Considering the evolutionary conservation of the components of this system, this novel regulatory mechanism could be used in other situations, both in bacteria and eukaryotes, where proteins are cotranslated with their insertion into cellular structures.
authors: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824-4320, USA. synderl@msu.edu
authors: Larry
authors: L
authors: Snyder
authors: Sherry
authors: S
authors: Blight
authors: Jennifer
authors: J
authors: Auchtung
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D017122:Bacteriophage T4 / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D036022:Capsid Proteins; D002478:Cells, Cultured; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006868:Hydrolysis; D007763:Lac Operon / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D008958:Models, Molecular; D010444:Peptide Elongation Factor Tu / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D012270:Ribosomes / Q000378:metabolism; D013379:Substrate Specificity; D014158:Transcription, Genetic; D014764:Viral Proteins; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D036022:Capsid Proteins; C041745:D protein, Enterobacteria phage lambda; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D014764:Viral Proteins; D001616:beta-Galactosidase; D010450:Endopeptidases; C094108:Lit protein, E coli; D010444:Peptide Elongation Factor Tu