5b2g
Crystal structure of human claudin-4 in complex with C-terminal fragment of Clostridium perfringens enterotoxinCrystal structure of human claudin-4 in complex with C-terminal fragment of Clostridium perfringens enterotoxin
Structural highlights
DiseaseCLD4_HUMAN CLDN4 is located in the Williams-Beuren syndrome (WBS) critical region. WBS results from a hemizygous deletion of several genes on chromosome 7q11.23, thought to arise as a consequence of unequal crossing over between highly homologous low-copy repeat sequences flanking the deleted region. FunctionCLD4_HUMAN Channel-forming tight junction protein that mediates paracellular chloride transport in the kidney. Plays a critical role in the paracellular reabsorption of filtered chloride in the kidney collecting ducts. Claudins play a major role in tight junction-specific obliteration of the intercellular space, through calcium-independent cell-adhesion activity.[UniProtKB:O35054]ENLYS_BPT4 Endolysin with lysozyme activity that degrades host peptidoglycans and participates with the holin and spanin proteins in the sequential events which lead to the programmed host cell lysis releasing the mature viral particles. Once the holin has permeabilized the host cell membrane, the endolysin can reach the periplasm and break down the peptidoglycan layer.[1] Publication Abstract from PubMedThe food-poisoning bacterium Clostridium perfringens produces an enterotoxin (~35 kDa) that specifically targets human claudin-4, among the 26 human claudin proteins, and causes diarrhea by fluid accumulation in the intestinal cavity. The C-terminal domain of the Clostridium perfringens enterotoxin (C-CPE, ~15 kDa) binds tightly to claudin-4, and disrupts the intestinal tight junction barriers. In this study, we determined the 3.5-A resolution crystal structure of the cell-free synthesized human claudin-4*C-CPE complex, which is significantly different from the structure of the off-target complex of an engineered C-CPE with mouse claudin-19. The claudin-4*C-CPE complex structure demonstrated the mechanism underlying claudin assembly disruption. A comparison of the present C-CPE-bound structure of claudin-4 with the enterotoxin-free claudin-15 structure revealed sophisticated C-CPE-induced conformation changes of the extracellular segments, induced on the foundation of the rigid four-transmembrane-helix bundle structure. These conformation changes provide a mechanistic model for the disruption of the lateral assembly of claudin molecules. Furthermore, the present novel structural mechanism for selecting a specific member of the claudin family can be used as the foundation to develop novel medically important technologies to selectively regulate the tight junctions formed by claudin family members in different organs. Structural basis for disruption of claudin assembly in tight junctions by an enterotoxin.,Shinoda T, Shinya N, Ito K, Ohsawa N, Terada T, Hirata K, Kawano Y, Yamamoto M, Kimura-Someya T, Yokoyama S, Shirouzu M Sci Rep. 2016 Sep 20;6:33632. doi: 10.1038/srep33632. PMID:27647526[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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