title: Thioredoxin is required for filamentous phage assembly.
abstract: Sequence comparisons show that the fip gene product of Escherichia coli, which is required for filamentous phage assembly, is thioredoxin. Thioredoxin serves as a cofactor for reductive processes in many cell types and is a constituent of phage T7 DNA polymerase. The fip-1 mutation makes filamentous phage and T7 growth temperature sensitive in cells that carry it. The lesion lies within a highly conserved thioredoxin active site. Thioredoxin reductase (NADPH), as well as thioredoxin, is required for efficient filamentous phage production. Mutant phages defective in phage gene I are particularly sensitive to perturbations in the fip-thioredoxin system. A speculative model is presented in which thioredoxin reductase, thioredoxin, and the gene I protein interact to drive an engine for filamentous phage assembly.
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000502:physiology*; D001483:Base Sequence; D003090:Coliphages / Q000254:growth & development*; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D009024:Morphogenesis; D009154:Mutation; D013879:Thioredoxins / Q000235:genetics / Q000502:physiology*; D014779:Virus Replication
chemical_list: D001426:Bacterial Proteins; D013879:Thioredoxins