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9hg5

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BAM-SurA complex in the swing-in state with full length BamC resolved

Structural highlights

9hg5 is a 6 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 2.82Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

BAMA_ECOLI Part of the outer membrane protein assembly complex, 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.^[1] ^[2] ^[3] ^[4] ^[5]

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^[6]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Doerrler WT, Raetz CR. Loss of outer membrane proteins without inhibition of lipid export in an Escherichia coli YaeT mutant. J Biol Chem. 2005 Jul 29;280(30):27679-87. Epub 2005 Jun 10. PMID:15951436 doi:http://dx.doi.org/M504796200
↑ Werner J, Misra R. YaeT (Omp85) affects the assembly of lipid-dependent and lipid-independent outer membrane proteins of Escherichia coli. Mol Microbiol. 2005 Sep;57(5):1450-9. PMID:16102012 doi:http://dx.doi.org/MMI4775
↑ Malinverni JC, Werner J, Kim S, Sklar JG, Kahne D, Misra R, Silhavy TJ. YfiO stabilizes the YaeT complex and is essential for outer membrane protein assembly in Escherichia coli. Mol Microbiol. 2006 Jul;61(1):151-64. PMID:16824102 doi:http://dx.doi.org/10.1111/j.1365-2958.2006.05211.x
↑ 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
↑ 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