Mutational analysis of the Caenorhabditis elegans cell-death gene ced-3.
Mutations in the gene ced-3, which encodes a protease similar to interleukin-1beta converting enzyme and related proteins termed caspases, prevent programmed cell death in the nematode Caenorhabditis elegans. We used site-directed mutagenesis to demonstrate that both the presumptive active-site cysteine of the CED-3 protease and the aspartate residues at sites of processing of the CED-3 proprotein are required for programmed cell death in vivo. We characterized the phenotypes caused by and the molecular lesions of 52 ced-3 alleles. These alleles can be ordered in a graded phenotypic series. Of the 30 amino acid sites altered by ced-3 missense mutations, 29 are conserved with at least one other caspase, suggesting that these residues define sites important for the functions of all caspases. Animals homozygous for the ced-3(n2452) allele, which is deleted for the region of the ced-3 gene that encodes the protease domain, seemed to be incompletely blocked in programmed cell death, suggesting that some programmed cell death can occur independently of CED-3 protease activity.
Shaham
S
S
Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Reddien
P W
PW
Davies
B
B
Horvitz
H R
HR
D000483:Alleles; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D020169:Caspases; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017931:DNA Primers; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017386:Sequence Homology, Amino Acid
D000596:Amino Acids; D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; D015801:Helminth Proteins; D020169:Caspases; D003546:Cysteine Endopeptidases; C089223:ced-3 protein, C elegans