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Structure of the sporulation/germination protein YhcN from Bacillus subtilisStructure of the sporulation/germination protein YhcN from Bacillus subtilis
Structural highlights
Function[YHCN_BACSU] Probably contributes, directly or indirectly, to early events in germination (PubMed:28333204). May play a role in spore outgrowth (PubMed:9611260).[1] [2] Publication Abstract from PubMedComponents of specialized secretion systems, which span the inner and outer membranes in Gram-negative bacteria, include ring-forming proteins whose oligomerization was proposed to be promoted by domains called RBM for "Ring-Building Motifs". During spore formation in Gram-positive bacteria, a transport system called the SpoIIIA-SpoIIQ complex also assembles in the double membrane that surrounds the forespore following its endocytosis by the mother cell. The presence of RBM domains in some of the SpoIIIA proteins led to the hypothesis that they would assemble into rings connecting the two membranes and form a conduit between the mother cell and forespore. Among them, SpoIIIAG forms homo-oligomeric rings in vitro but the oligomerization of other RBM-containing SpoIIIA proteins, including SpoIIIAH, remains to be demonstrated. In this work, we identified RBM domains in the YhcN/YlaJ family of proteins that are not related to the SpoIIIA-SpoIIQ complex. We solved the crystal structure of YhcN from Bacillus subtilis, which confirmed the presence of a RBM fold, flanked by additional secondary structures. As the protein did not show any oligomerization ability in vitro, we investigated the structural determinants of ring formation in SpoIIIAG, SpoIIIAH and YhcN. We showed that in vitro, the conserved core of RBM domains alone is not sufficient for oligomerization while the beta-barrel forming region in SpoIIIAG forms rings on its own. This work suggests that some RBMs might indeed participate in the assembly of homomeric rings but others might have evolved toward other functions. Structural insights into ring-building motif domains involved in bacterial sporulation.,Liu B, Chan H, Bauda E, Contreras-Martel C, Bellard L, Villard AM, Mas C, Neumann E, Fenel D, Favier A, Serrano M, Henriques AO, Rodrigues CDA, Morlot C J Struct Biol. 2022 Mar;214(1):107813. doi: 10.1016/j.jsb.2021.107813. Epub 2021 , Nov 19. PMID:34808342[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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