tailieunhanh - Báo cáo khoa học: YidC is required for the assembly of the MscL homopentameric pore

The mechanosensitive channel with large conductance (MscL) ofEscheri-chia coliis formed by a homopentameric assembly of MscL proteins. Here, we describe MscL biogenesis as determined usingin vivo approaches. Evi-dence is presented that MscL is targeted to the inner membrane via the sig-nal recognition particle (SRP) pathway, and is inserted into the lipid bilayer independently of the Sec machinery. | ỊFEBS Journal YidC is required for the assembly of the MscL homopentameric pore Ovidiu I. Pop1 Zora Soprova1 Gregory Koningstein1 Dirk-Jan Scheffers1 2 Peter van Ulsen1 David Wickstrom3 Jan-Willem de Gier3 and Joen Luirink1 1 Section Molecular Microbiology Department of Molecular CellBiology VU University Amsterdam The Netherlands 2 BacterialMembrane Proteomics Laboratory Instituto de Tecnologia Química e Biológica Avenida da Republica Estacao Agronomica Nacional Oeiras Portugal 3 Center for Biomembrane Research Department of Biochemistry and Biophysics Arrhenius Laboratories Stockholm University Sweden Keywords membrane protein complex assembly membrane protein insertion MscL SRP YidC Correspondence J. Luirink Section Molecular Microbiology Department of Molecular Cell Biology VU University De Boelelaan 1085 1081 HV Amsterdam The Netherlands Fax 31 20 5986979 Tel 31 20 5987175 E-mail Received 8 April2009 revised 22 June 2009 accepted 30 June 2009 The mechanosensitive channel with large conductance MscL of Escherichia coli is formed by a homopentameric assembly of MscL proteins. Here we describe MscL biogenesis as determined using in vivo approaches. Evidence is presented that MscL is targeted to the inner membrane via the signal recognition particle SRP pathway and is inserted into the lipid bilayer independently of the Sec machinery. This is consistent with published data. Surprisingly and in conflict with earlier data YidC is not critical for membrane insertion of MscL. In the absence of YidC assembly of the homopentameric MscL complex was strongly reduced suggesting a late role for YidC in the biogenesis of MscL. The data are consistent with the view that YidC functions as a membrane-based chaperone module to facilitate assembly of a subset of protein complexes in the inner membrane of E. coli. doi Introduction Membrane proteins are responsible for a variety of cellular functions such as solute transport