4itr | pdb_00004itr
Crystal Structure of IbpAFic2-H3717A in complex with adenylylated Cdc42
Structural highlights
Function[IBPA_HISS2] Adenylyltransferase involved in virulence by mediating the addition of adenosine 5'-monophosphate (AMP) to specific tyrosine residue of host Rho GTPases RhoA, Rac and Cdc42. The resulting AMPylation inactivates Rho GTPases, thereby inhibiting actin assembly in infected cells. Probably also acts as a cysteine protease, which may play a central role after invasion of host cell and in virulence. Possible member (with IbpB) of a 2 partner secretion. Probably able to bind bovine epithelial cells (host cells). May participate in the formation of fibrils at the surface of the bacteria.[1] [2] [3] [4] [CDC42_HUMAN] Plasma membrane-associated small GTPase which cycles between an active GTP-bound and an inactive GDP-bound state. In active state binds to a variety of effector proteins to regulate cellular responses. Involved in epithelial cell polarization processes. Regulates the bipolar attachment of spindle microtubules to kinetochores before chromosome congression in metaphase. Plays a role in the extension and maintenance of the formation of thin, actin-rich surface projections called filopodia. Mediates CDC42-dependent cell migration.[5] [6] [7] Publication Abstract from PubMedThe Fic family of adenylyltransferases, defined by a core HPFx(D/E)GN(G/K)R motif, consists of over 2,700 proteins found in organisms from bacteria to humans. The immunoglobulin-binding protein A (IbpA) from the bacterial pathogen Histophilus somni contains two Fic domains that adenylylate the switch1 tyrosine residue of Rho-family GTPases, allowing the bacteria to subvert host defenses. Here we present the structure of the second Fic domain of IbpA (IbpAFic2) in complex with its substrate, Cdc42. IbpAFic2-bound Cdc42 mimics the GDI-bound state of Rho GTPases, with both its switch1 and switch2 regions gripped by IbpAFic2. Mutations disrupting the IbpAFic2-Cdc42 interface impair adenylylation and cytotoxicity. Notably, the switch1 tyrosine of Cdc42 is adenylylated in the structure, providing the first structural view for this post-translational modification. We also show that the nucleotide-binding mechanism is conserved among Fic proteins and propose a catalytic mechanism for this recently discovered family of enzymes. Structural basis of Fic-mediated adenylylation.,Xiao J, Worby CA, Mattoo S, Sankaran B, Dixon JE Nat Struct Mol Biol. 2010 Aug;17(8):1004-10. Epub 2010 Jul 11. PMID:20622875[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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