Literature summary for 2.4.1.B62 extracted from

Chen, S.; Wang, H.; Gu, H.; Sun, C.; Li, S.; Feng, H.; Wang, J.
Identification of an essential region for translocation of Clostridium difficile toxin B (2016), Toxins, 8, 241 .

Search for more literature for 2.4.1.B62

Cloned(Commentary)

Cloned (Comment)	Organism
gene tcdB, recombinant expression of C-terminally His6-tagged deletion mutants in a Bacillus megaterium expression system	Clostridioides difficile

Protein Variants

Protein Variants	Comment	Organism
additional information	25AA (1756-1780) are deleted to construct the deletion mutant TcdBD1756-1780. The deletion mutant TcdBD1827-1851, with deletion of a different 25AA, 1827-1851, located in the C-terminus of D97, serves as the control. The deletion mutants are expressed with His6-tags at the C-terminal in a Bacillus megaterium expression system. Wild-type and mutant toxins are introduced into mouse CT26 host cells. Both TcdBD1756-1780 and TcdBfl successfully induce autocleavage, releasing a 63kD fragment containing GTD, in the presence of InsP6. TcdBD1756-1780 undergoes autocleavage after incubation with a series of concentrations of InsP6 for several hours. The TcdBD1756-1780 mutant efficiently induces Rac1 glucosylation using CT26 cell lysate as the substrate, but fails to glucosylate Rac1 in intact CT26 cells. Thus, the deletion of amino acids 1756-1780 does not change the structure and function of the cysteine protease and glucosytransferase domains, but may result in an inability to deliver GTD into the host cytosol. The deletion of region 1756-1780 might lead to locking of the TcdB in endosomes, resulting in a failure to deliver GTD	Clostridioides difficile

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
UDP-alpha-D-glucose + a small GTPase	Clostridioides difficile	-	UDP + D-glucosyl-[a small GTPase]	-	?
UDP-alpha-D-glucose + murine Rho GTPase	Clostridioides difficile	-	UDP + D-glucosyl-[murine Rho GTPase]	-	?

Organism

Organism	UniProt	Comment	Textmining
Clostridioides difficile	P18177	-	-

Posttranslational Modification

Posttranslational Modification	Comment	Organism
proteolytic modification	the toxin requires InsP6-dependent autocleavage for activation	Clostridioides difficile

Purification (Commentary)

Purification (Comment)	Organism
recombinant C-terminally His6-tagged deletion mutants from Bacillus megaterium by nickel affinity chromatography	Clostridioides difficile

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
UDP-alpha-D-glucose + a small GTPase	-	Clostridioides difficile	UDP + D-glucosyl-[a small GTPase]	-	?
UDP-alpha-D-glucose + murine Rho GTPase	-	Clostridioides difficile	UDP + D-glucosyl-[murine Rho GTPase]	-	?

Subunits

Subunits	Comment	Organism
More	the toxins are multi-domain proteins containing at least four functional domains. The N-terminus of the toxin harbors the glucosyltransferase domain (GTD) that inactivates host Rho GTPases by glucosylation and a cysteine protease domain (CPD) responsible for autoprocessing. The C-terminus, consisting of combined repetitive oligopeptides (CROP), is predicted to be a receptor binding domain (RBD)	Clostridioides difficile

Synonyms

Synonyms	Comment	Organism
TcdB	-	Clostridioides difficile
toxin B	-	Clostridioides difficile

General Information

General Information	Comment	Organism
malfunction	the deletion mutant TcdBD1756-1780 shows similar glucosyltransferase and cysteine protease activity, cellular binding, and pore formation to wild-type TcdB, but it fails to induce the glucosylation of Rho GTPase Rac1 of host cells. Moreover, TcdBD1756-1780 is rapidly degraded in the endosome of target cells, and therefore its intact glucosyltransferase domain is unable to translocate efficiently into host cytosol. The decrease in the alpha helical structure in the composition of TcdBD1756-1780 may be due to the deletion of AA 1756-1780. Domain structures of wild-type and mutant enzymes, overview. The deletion of region 1756-1780 might lead to locking of the TcdB in endosomes, resulting in a failure to deliver GTD	Clostridioides difficile
additional information	the toxin requires InsP6-dependent autocleavage for activation	Clostridioides difficile
physiological function	two exotoxins, toxin A (TcdA) and toxin B (TcdB), are the major virulence factors involved in Clostridium difficile infection (CDI), and both belong to the family of clostridial glucosylating toxins. The toxins are multi-domain proteins containing at least four functional domains. The N-terminus of the toxin harbors the glucosyltransferase domain (GTD) that inactivates host Rho GTPases by glucosylation and a cysteine protease domain (CPD) responsible for autoprocessing. The C-terminus, consisting of combined repetitive oligopeptides (CROP), is predicted to be a receptor binding domain (RBD). The receptor for TcdB has been identified recently, but additional receptors may exist. A large region between the CPD and RBD is thought to be the translocation domain (TD) which is important for delivery of N-terminal enzymatic domains into the host cytosol via pore formation. The segment of 97 amino acids (AA 1756-1852, designated D97) within the translocation domain of TcdB is essential for the in vitro and in vivo toxicity of TcdB. smaller fragment, amino acids 1756-1780, located in the N-terminus of the D97 fragment, is essential for translocation of the effector glucosyltransferase domain into the host cytosol. A sequence of 25AA within D97 is predicted to form an alpha helical structure and is the critical part of D97	Clostridioides difficile

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Release 2023.1 (January 2023)