BamABCDE complex OM biogenesis outer membrane pore-forming assembly factor; Part of the outer membrane protein assembly complex (Bam), which is involved in assembly and insertion of beta-barrel proteins into the outer membrane. Constitutes, with BamD, the core component of the assembly machinery. Efficient substrate folding and insertion into the outer membrane requires all 5 subunits. A lateral gate may open between the first and last strands of the BamA beta-barrel that allows substrate to insert into the outer membrane; comparison of the structures of complete and nearly complete Ba [...]

Periplasmic chaperone; Molecular chaperone that interacts specifically with outer membrane proteins, thus maintaining the solubility of early folding intermediates during passage through the periplasm. Required for the efficient release of OmpA from the inner membrane, the maintenance of its solubility in the periplasm, and, in association with lipopolysaccharide (LPS), for the efficient folding and insertion of OmpA into the outer membrane. Belongs to the Skp family.

FKBP-type peptidyl-prolyl cis-trans isomerase (rotamase); PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides.

Membrane protein insertase; Inner membrane protein required for the insertion and/or proper folding and/or complex formation of integral inner membrane proteins. Involved in integration of membrane proteins that insert dependently and independently of the Sec translocase complex, as well as at least 2 lipoproteins. Its own insertion requires SRP and is Sec translocase-dependent. Essential for the integration of Sec-dependent subunit a of the F(0)ATP synthase, FtsQ and SecE proteins and for Sec- independent subunit c of the F(0)ATP synthase, M13 phage procoat and the N-terminus of leade [...]

Preprotein translocase membrane subunit; The central subunit of the protein translocation channel SecYEG. Consists of two halves formed by TMs 1-5 and 6-10. These two domains form a lateral gate at the front which open onto the bilayer between TMs 2 and 7, and are clamped together by SecE at the back. The channel is closed by both a pore ring composed of hydrophobic SecY resides and a short helix (helix 2A) on the extracellular side of the membrane which forms a plug. The plug probably moves laterally to allow the channel to open. The ring and the pore may move independently. SecY is r [...]

Peptidyl-prolyl cis/trans isomerase (trigger factor); Involved in protein export. Acts as a chaperone by maintaining the newly synthesized secretory and non-secretory proteins in an open conformation. Binds to 3 regions of unfolded substrate PhoA, preferring aromatic and hydrophobic residues, keeping it stretched out and unable to form aggregates. Binds to nascent polypeptide chains via ribosomal protein L23. Functions as a peptidyl-prolyl cis-trans isomerase in vitro, this activity is dispensible in vivo for chaperone activity. Belongs to the FKBP-type PPIase family. Tig subfamily.

BamABCDE complex OM biogenesis lipoprotein; Part of the outer membrane protein assembly complex (Bam), which is involved in assembly and insertion of beta-barrel proteins into the outer membrane. Nonessential member of the complex, which may orient the flexible periplasmic domain of BamA for interaction with other Bam components, chaperones and nascent outer membrane proteins. Efficient substrate folding and insertion into the outer membrane requires all 5 subunits. A lateral gate may open between the first and last strands of the BamA beta-barrel that allows substrate to insert into t [...]

Serine endoprotease (protease Do), membrane-associated; DegP acts as a chaperone at low temperatures but switches to a peptidase (heat shock protein) at higher temperatures. Degrades transiently denatured and unfolded or misfolded proteins which accumulate in the periplasm following heat shock or other stress conditions. DegP is efficient with Val-Xaa and Ile-Xaa peptide bonds, suggesting a preference for beta-branched side chain amino acids. Only unfolded proteins devoid of disulfide bonds appear capable of being cleaved, thereby preventing non-specific proteolysis of folded proteins. [...]

Preprotein translocase subunit, ATPase; Required for protein export, interacts with the SecYEG preprotein conducting channel. SecA has a central role in coupling the hydrolysis of ATP to the transfer of proteins into and across the cell membrane, serving both as a receptor for the preprotein-SecB complex and as an ATP-driven molecular motor driving the stepwise translocation of polypeptide chains across the membrane.