title: Protein translocation across the inner membrane of Gram-negative bacteria: the Sec and Tat dependent protein transport pathways.
abstract: Gram negative bacteria possess a large variety of protein transport systems, by which proteins that are synthesised in the cytosol are exported to destinations in the cell envelope or entirely secreted into the extracellular environment. The inner membrane (IM) contains three major transport systems for the translocation and insertion of signal sequence containing proteins: the Sec translocon, the YidC insertase, and the Tat system. The heterotrimeric SecYEG translocon forms a narrow channel in the membrane that serves a dual function; it allows the translocation of unfolded proteins across the pore and the integration of α-helical proteins into the IM. The YidC insertase is a multi-spanning membrane protein that cooperates with the SecYEG translocon during the integration of membrane proteins but also functions as an independent insertase. Depending upon the type of protein cargo that needs to be transported, the Signal Recognition Particle (SRP), the SRP receptor, SecA and chaperones are required to coordinate translation with transport and to target and energise the different transport systems. The Tat system consists of three membrane proteins (TatA, TatB and TatC) which in a still unknown manner accomplish the transmembrane passage of completely folded proteins and protein complexes.
authors.affiliation: Institut für Biochemie und Molekularbiologie, Germany.
authors.forename: Renuka
authors.initials: R
authors.lastname: Kudva
authors.forename: Kärt
authors.initials: K
authors.lastname: Denks
authors.forename: Patrick
authors.initials: P
authors.lastname: Kuhn
authors.forename: Andreas
authors.initials: A
authors.lastname: Vogt
authors.forename: Matthias
authors.initials: M
authors.lastname: Müller
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Koch
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D006090:Gram-Negative Bacteria / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems
keywords: Chaperone proteins; Gram-negative bacteria; Inner membrane; Protein translocation; Sec-dependent pathway; Tat-dependent pathway