Chaudhary D et al. (1998) J Biol Chem "The death inhibitory molecules CED-9 and CED-4L use a common mechanism to inhibit the CED-3 death protease."

Dixit VM, Chinnaiyan AM, O'Rourke K, Chaudhary D

[J Biol Chem, 1998]

The apoptotic machinery of Caenorhabditis elegans includes three core interacting components: CED-3, CED-4, and CED-9. CED-3 is a death protease composed of a prodomain and a protease domain. CED-4 is a P-loop-containing, nucleotide-binding molecule that complexes with the single polypeptide zymogen form of CED-3, promoting its activation by autoprocessing. CED-9 blocks death by complexing with CED-4 and suppressing its ability to promote CED-3 activation. A naturally occurring alternatively spliced form of CED-4 that contains an insertion within the nucleotide-binding region (CED-4L) functions as a dominant negative inhibitor of CED-3 processing and attenuates cell death. Domain mapping studies revealed that distinct regions within CED-4 bind to the CED-3 prodomain and protease domain. Importantly, the CED-4 P-loop was involved in prodomain binding. Disruption of P-loop geometry because of mutation of a critical lysine (K165R) or insertional inactivation (CED-4L) abolished prodomain binding. Regardless, K165R and CED-4L still retained CED-3 binding through the protease domain but were unable to initiate CED-3 processing. Therefore, the P-loop-prodomain interaction is critical for triggering CED-4-mediated CED-3 processing. Underscoring the importance of this interaction was the finding that CED-9 contacted the P-loop and selectively inhibited its interaction with the CED-3 prodomain. These results provide a simple mechanism for how CED-9 functions to block CED-4-mediated CED-3 processing and cell death.

Divya Chaudhary

aldose beta-D-fructosyltransferase activity

Catalysis of the reaction: alpha-D-aldosyl1 beta-D-fructoside + D-aldose2 = D-aldose1 + alpha-D-aldosyl2 beta-D-fructoside.

lacto-N-biosidase activity

Catalysis of the reaction: H2O + beta-D-Gal-(1,3)-beta-D-GlcNAc-(1,3)-beta-D-Gal-(1,4)-D-Glc = beta-D-Gal-(1,4)-D-Glc + beta-D-Gal-(1,3)-D-GlcNAc.

mannotetraose 2-alpha-N-acetylglucosaminyltransferase activity

Catalysis of the reaction: 1,3-alpha-D-mannosyl-1,2-alpha-D-mannosyl-1,2-alpha-D-mannosyl-D-mannose + UDP-N-acetyl-D-glucosamine = 1,3-alpha-D-mannosyl-1,2-(N-acetyl-alpha-D-glucosaminyl-alpha-D-mannosyl)-1,2-alpha-D-mannosyl-D-mannose + UDP.

globoside alpha-N-acetylgalactosaminyltransferase activity

Catalysis of the reaction: N-acetyl-D-galactosaminyl-(1,3)-D-galactosyl-(1,4)-D-galactosyl-(1,4)-D-glucosylceramide + UDP-N-acetylgalactosamine = N-acetyl-D-galactosaminyl-N-acetyl-D-galactosaminyl-(1,3)-D-galactosyl-(1,4)-D-galactosyl-(1,4)-D-glucosylceramide + UDP.

dol-P-Man:Man(5)GlcNAc(2)-PP-Dol alpha-1,3-mannosyltransferase activity

Catalysis of the reaction: an alpha-D-man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-(alpha-D-Man-(1->6))-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl D-mannosyl phosphate = H+ + alpha-D-Man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-(alpha-D-Man-(1->3)-alpha-D-Man-(1->6))-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl phosphate.

glucosaminylgalactosylglucosylceramide beta-galactosyltransferase activity

Catalysis of the reaction: N-acetyl-D-glucosaminyl-(1,3)-D-galactosyl-(1,4)-D-glucosylceramide + UDP-galactose = D-galactosyl-N-acetyl-D-glucosaminyl-(1,3)-D-galactosyl-(1,4)-D-glucosylceramide + UDP.

glucose-fructose oxidoreductase activity

Catalysis of the reaction: D-fructose + D-glucose = D-glucitol + D-glucono-1,5-lactone.

dol-P-Man:Man(6)GlcNAc(2)-PP-Dol alpha-1,2-mannosyltransferase activity

Catalysis of the reaction: alpha-D-man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-(alpha-D-Man-(1->3)-alpha-D-Man-(1->6))-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl D-mannosyl phosphate = H+ + alpha-D-Man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-(alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-alpha-D-Man-(1->6))-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl phosphate.