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crystal structure of MBP-tagged REV7-IpaB complexcrystal structure of MBP-tagged REV7-IpaB complex
Structural highlights
FunctionMALE_ECOLI Involved in the high-affinity maltose membrane transport system MalEFGK. Initial receptor for the active transport of and chemotaxis toward maltooligosaccharides.MD2L2_HUMAN Adapter protein able to interact with different proteins and involved in different biological processes. Mediates the interaction between the error-prone DNA polymerase zeta catalytic subunit REV3L and the inserter polymerase REV1, thereby mediating the second polymerase switching in translesion DNA synthesis. Translesion DNA synthesis releases the replication blockade of replicative polymerases, stalled in presence of DNA lesions. May also regulate another aspect of cellular response to DNA damage through regulation of the JNK-mediated phosphorylation and activation of the transcriptional activator ELK1. Inhibits the FZR1- and probably CDC20-mediated activation of the anaphase promoting complex APC thereby regulating progression through the cell cycle. Regulates TCF7L2-mediated gene transcription and may play a role in epithelial-mesenchymal transdifferentiation.[1] [2] [3] [4] [5] REV3L_HUMAN Catalytic subunit of the DNA polymerase zeta complex, an error-prone polymerase specialized in translesion DNA synthesis (TLS). Lacks an intrinsic 3'-5' exonuclease activity and thus has no proofreading function.[6] IPAB_SHIFL Effector proteins function to alter host cell physiology and promote bacterial survival in host tissues. Forms a pore with IpaC, which is inserted into the host cell membrane through the Mxi/Spa apparatus, during cell contact. This pore probably allows the translocation of IpaA. IpaB has also been found to be necessary and sufficient to activate macrophage apoptosis by binding to interleukin-1 beta converting enzyme (ICE). Has also been shown to be important, along with IpaD, to block or regulate secretion through the Mxi/Spa translocon in the presence or absence of the secretion signal, respectively. Through interaction with host human MAD2L2, constitutively activates the anaphase-promoting complex APC and induces a cell cycle arrest to prevent epithelial renewal in order to promote bacterial colonization.[7] [8] Publication Abstract from PubMedREV7, also termed mitotic arrest-deficient 2-like 2 (MAD2L2 or MAD2B), acts as an interaction module in a broad array of cellular pathways, including translesion DNA synthesis, cell cycle control, and nonhomologous end joining. Numerous REV7 binding partners have been identified, including the human small GTPase Ras-associated nuclear protein (RAN), which acts as a potential upstream regulator of REV7. Notably, the Shigella invasin IpaB hijacks REV7 to disrupt cell cycle control to prevent intestinal epithelial cell renewal and facilitate bacterial colonization. However, the structural details of the REV7-RAN and REV7-IpaB interactions are mostly unknown. Here, using fusion protein and rigid maltose-binding protein tagging strategies, we determined the crystal structures of these two complexes at 2.00-2.35 A resolutions. The structures revealed that both RAN and IpaB fragments bind the "safety belt" region of REV7, inducing rearrangement of the C-terminal beta-sheet region of REV7, conserved among REV7-related complexes. Of note, the REV7-binding motifs of RAN and IpaB each displayed some unique interactions with REV7 despite sharing consensus residues. Structural alignments revealed that REV7 has an adaptor region within the safety belt region that can rearrange secondary structures to fit a variety of different ligands. Our structural and biochemical results further indicated that REV7 preferentially binds GTP-bound RAN, implying that a GTP/GDP-bound transition of RAN may serve as the molecular switch that controls REV7's activity. These results provide insights into the regulatory mechanism of REV7 in cell cycle control, which may help with the development of small-molecule inhibitors that target REV7 activity. REV7 has a dynamic adaptor region to accommodate small GTPase RAN/Shigella IpaB ligands, and its activity is regulated by the RanGTP/GDP switch.,Wang X, Pernicone N, Pertz L, Hua D, Zhang T, Listovsky T, Xie W J Biol Chem. 2019 Oct 25;294(43):15733-15742. doi: 10.1074/jbc.RA119.010123. Epub, 2019 Sep 4. PMID:31484720[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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