SecA: Difference between revisions
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=Introduction= | =Introduction= | ||
The [http://www.nature.com/nature/journal/v455/n7215/full/nature07335.html SecA] ATPase SecA drives the post-translational translocation of proteins through the SecY channel in the bacterial inner membrane. SecA is a dimer that can dissociate into monomers under certain conditions. Many bacterial proteins are transported post-translationally across the inner membrane by the Sec machinery, which consists of two essential components (1-4). One is the SecY complex, which forms a conserved heterotrimeric protein-conducting channel in the inner membrane.<ref name=journal1>PMID:15618215</ref> The other is SecA, a cytoplasmic ATPase, which "pushes" substrate polypeptide chains through the SecY channel.<ref name=journal1/> | The [http://www.nature.com/nature/journal/v455/n7215/full/nature07335.html SecA] ATPase '''SecA''' drives the post-translational translocation of proteins through the SecY channel in the bacterial inner membrane. SecA is a dimer that can dissociate into monomers under certain conditions. Many bacterial proteins are transported post-translationally across the inner membrane by the Sec machinery, which consists of two essential components (1-4). One is the SecY complex, which forms a conserved heterotrimeric protein-conducting channel in the inner membrane.<ref name=journal1>PMID:15618215</ref> The other is SecA, a cytoplasmic ATPase, which "pushes" substrate polypeptide chains through the SecY channel.<ref name=journal1/> | ||
{{ STRUCTURE_3jv2 | PDB=3jv2 | SCENE=Sandbox_158/Scene_1/1 }} | |||
{{STRUCTURE_3jv2| PDB=3jv2 | SIZE=400| SCENE=Sandbox_158/Scene_1/1 |right|CAPTION=SecA complex with peptide and ADPn, [[3jv2]] }} | |||
=Structure= | =Structure= | ||
[http://www.nature.com/nature/journal/v455/n7215/full/nature07335.html SecA] SecA consists of two RecA-like nucleotide-binding domains (NBD1 and NBD2), which bind the nucleotide between them, a polypeptide-cross-linking domain (PPXD), a helical scaffold domain (HSD) and a helical wing domain (HWD)<ref name=journal2>PMID:18923516</ref> Although several crystal structures of isolated SecA have been determined, the function of the different domains and the mechanism by which SecA moves polypeptides through the channel remain unknown. Disulphide cross-linking experiments suggest that SecA binds by its NBD1 domain to a non-translocating SecY copy, and moves the polypeptide chain through a neighbouring SecY molecule6. These and other experiments indicate that SecA functions as a monomer during translocation<ref name=journal2/>but the issue remains controversial.<ref name=journal2/> | [http://www.nature.com/nature/journal/v455/n7215/full/nature07335.html SecA] SecA consists of two RecA-like nucleotide-binding domains (NBD1 and NBD2), which bind the nucleotide between them, a polypeptide-cross-linking domain (PPXD), a helical scaffold domain (HSD) and a helical wing domain (HWD)<ref name=journal2>PMID:18923516</ref> Although several crystal structures of isolated SecA have been determined, the function of the different domains and the mechanism by which SecA moves polypeptides through the channel remain unknown. Disulphide cross-linking experiments suggest that SecA binds by its NBD1 domain to a non-translocating SecY copy, and moves the polypeptide chain through a neighbouring SecY molecule6. These and other experiments indicate that SecA functions as a monomer during translocation<ref name=journal2/>but the issue remains controversial.<ref name=journal2/> | ||
