1qyn
From Proteopedia
Crystal Structure of SecB from Escherichia coli
Structural highlights
FunctionSECB_ECOLI One of the proteins required for the normal export of some preproteins out of the cell cytoplasm. It is a molecular chaperone that binds to a subset of precursor proteins, maintaining them in a translocation-competent state. It also specifically binds to its receptor SecA. Its substrates include AmpC, DegP, FhuA, FkpA, GBP, LamB, MalE (MBP), OmpA, OmpF, OmpT, OmpX, OppA, PhoE, TolB, TolC, YbgF, YcgK, YgiW and YncE.[HAMAP-Rule:MF_00821] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe chaperone SecB from Escherichia coli is primarily involved in passing precursor proteins into the Sec system via specific interactions with SecA. The crystal structure of SecB from E. coli has been solved to 2.35 A resolution. The structure shows flexibility in the crossover loop and the helix-connecting loop, regions that have been implicated to be part of the SecB substrate-binding site. Moreover conformational variability of Trp36 is observed as well as different loop conformations for the different monomers. Based on this, we speculate that SecB can regulate the access or extent of its hydrophobic substrate-binding site, by modulating the conformation of the crossover loop and the helix-connecting loop. The structure also clearly explains why the tetrameric equilibrium is shifted towards the dimeric state in the mutant SecBCys76Tyr. The buried cysteine residue is crucial for tight packing, and mutations are likely to disrupt the tetramer formation but not the dimer formation. Crystal structure of SecB from Escherichia coli.,Dekker C, de Kruijff B, Gros P J Struct Biol. 2003 Dec;144(3):313-9. PMID:14643199[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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