Structural highlights
Function
BAMB_ECOLI Part of the outer membrane protein assembly complex, 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.[1] [2] [3] [4]
Publication Abstract from PubMed
The proper folding of outer membrane proteins in Gram-negative bacteria relies on their delivery to the beta-barrel assembly machinery (BAM) complex. The mechanism by which survival protein A (SurA), the major periplasmic chaperone, facilitates this process is not well understood. We determine the structure of the holo insertase complex, where SurA binds BAM for substrate delivery. High-resolution cryo-electron microscopy structures of four different states and a three-dimensional variability analysis show that the holo insertase complex has a large motional spectrum. SurA bound to BAM can undergo a large swinging motion between two states. This motion is uncoupled from the conformational flexibility of the BamA barrel, which can open and close without affecting SurA binding. Notably, we observed conformational coupling of the SurA swing state and the carboxyl-terminal helix grip domain of BamC. Substrate delivery by SurA to BAM appears to follow a concerted motion that encodes a gated delivery pathway through the BAM accessory proteins to the membrane entry site.
Architecture and conformational dynamics of the BAM-SurA holo insertase complex.,Lehner PA, Degen M, Jakob RP, Modaresi SM, Callon M, Burmann BM, Maier T, Hiller S Sci Adv. 2025 Apr 4;11(14):eads6094. doi: 10.1126/sciadv.ads6094. Epub 2025 Apr , 4. PMID:40184469[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Hagan CL, Kim S, Kahne D. Reconstitution of outer membrane protein assembly from purified components. Science. 2010 May 14;328(5980):890-2. doi: 10.1126/science.1188919. Epub 2010 Apr, 8. PMID:20378773 doi:10.1126/science.1188919
- ↑ Hagan CL, Kahne D. The reconstituted Escherichia coli Bam complex catalyzes multiple rounds of beta-barrel assembly. Biochemistry. 2011 Sep 6;50(35):7444-6. doi: 10.1021/bi2010784. Epub 2011 Aug 11. PMID:21823654 doi:10.1021/bi2010784
- ↑ Albrecht R, Zeth K. Structural basis of outer membrane protein biogenesis in bacteria. J Biol Chem. 2011 Aug 5;286(31):27792-803. Epub 2011 May 17. PMID:21586578 doi:10.1074/jbc.M111.238931
- ↑ Noinaj N, Fairman JW, Buchanan SK. The Crystal Structure of BamB Suggests Interactions with BamA and Its Role within the BAM Complex. J Mol Biol. 2011 Jan 26. PMID:21277859 doi:10.1016/j.jmb.2011.01.042
- ↑ Lehner PA, Degen M, Jakob RP, Modaresi SM, Callon M, Burmann BM, Maier T, Hiller S. Architecture and conformational dynamics of the BAM-SurA holo insertase complex. Sci Adv. 2025 Apr 4;11(14):eads6094. PMID:40184469 doi:10.1126/sciadv.ads6094
