Assembly of membrane-bound respiratory complexes by the Tat protein-transport system.
The Tat protein-export system serves to translocate folded proteins, often containing redox cofactors, across the bacterial inner membrane. Substrate proteins are directed to the Tat apparatus by distinctive N-terminal signal peptides containing a consensus SRRxFLK 'twin-arginine' motif. Here we review recent studies of the Tat system with particular emphasis on the assembly of membrane-bound respiratory complexes. We discuss the connection between Tat targeting and topological organisation of the complexes and consider the role of chaperone proteins in cofactor insertion and Tat targeting. The crystal structure of Escherichia coli formate dehydrogenase-N demonstrates that some Tat substrates are integral membrane proteins. Sequence analysis suggests that one-quarter of all traffic on the E. coli Tat pathway is inner-membrane proteins.
Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK. f.sargent@uea.ac.uk
Frank
F
Sargent
Ben C
BC
Berks
Tracy
T
Palmer
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005560:Formate Dehydrogenases / Q000737:chemistry / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D001426:Bacterial Proteins; D002352:Carrier Proteins; C434268:DmsD protein, E coli; D029968:Escherichia coli Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; C088083:TorD protein, E coli; C408585:twin-arginine translocase complex, E coli; D005560:Formate Dehydrogenases