title: Truncation analysis of TatA and TatB defines the minimal functional units required for protein translocation.
abstract: The TatA and TatB proteins are essential components of the twin arginine protein translocation pathway in Escherichia coli. C-terminal truncation analysis of the TatA protein revealed that a plasmid-expressed TatA protein shortened by 40 amino acids is still fully competent to support protein translocation. Similar truncation analysis of TatB indicated that the final 30 residues of TatB are dispensable for function. Further deletion experiments with TatB indicated that removal of even 70 residues from its C terminus still allowed significant transport. These results imply that the transmembrane and amphipathic helical regions of TatA and TatB are critical for their function but that the C-terminal domains are not essential for Tat transport activity. A chimeric protein comprising the N-terminal region of TatA fused to the amphipathic and C-terminal domains of TatB supports a low level of Tat activity in a strain in which the wild-type copy of either tatA or tatB (but not both) is deleted.
authors.affiliation: Department of Molecular Microbiology, John Innes Centre, Norwich NR4 7UH, UK.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Lee
authors.forename: Grant
authors.initials: G
authors.lastname: Buchanan
authors.forename: Nicola R
authors.initials: NR
authors.lastname: Stanley
authors.forename: Ben C
authors.initials: BC
authors.lastname: Berks
authors.forename: Tracy
authors.initials: T
authors.lastname: Palmer
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001665:Binding Sites; D001692:Biological Transport; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D016296:Mutagenesis
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C499697:TatA protein, E coli; C467897:TatE protein, E coli; C408585:twin-arginine translocase complex, E coli