We have isolated twelve C. elegans cDNAs that trans-complemented the fission yeast
mes1 mutation, which causes a defect in the second meiotic division (1, 2). Half of these cDNAs encoded cytoskeletal proteins (two alpha-tubulin, two beta-tubulin and two actin genes) suggesting the importance of cytoskeletal rearrengement in meiosisII. We further characterized one of the genes isolated in this screen, which we named
kel-1.
kel-1 encodes a 618-amino-acid polypeptide that shows similarity with Drosophila Kelch throughout the protein, which is known to be essential for oogenesis. Mammalian NRP/B, which has been implicated in neuronal differentiation also showed overall similarity with KEL-1. These proteins carry a motif called "kelch repeat" which consists of two to seven repeats of ~50 amino acids. KEL-1 also showed weak similarity with C.elegans SPE-26 and Limulus alpha- and beta-Scruin in this motif. Although many kelch repeat-containing proteins have been found from various species, the function of this motif is still unclear except that alpha-Scruin is known to interact with actin. To investigate the function of the
kel-1 gene product, animals mutagenized with UV-trimethylpsoralen were screened for deletion alleles and one deletion allele,
kel-1(
pe201), was isolated. This
kel-1 deletion mutant, which lacks most of the polypeptide, arrested at the early larval stage. However, most mutant animals were not dead soon after the arrest. They survived for several days after hatching and their movement and morphology was essentially normal, except that they accumulated granules throughout their bodies. We investigated the localization of KEL-1 using anti-KEL-1 antibodies and a
kel-1::GFP reporter. KEL-1 localized to the pharyngeal
g1 gland cells at all stages after late embryogenesis. The
g1 gland cells have been suggested to play a role in molting and digestion. L1 lethargus and subsequent molting occurred in the
kel-1 deletion mutants, although slightly later than control animals. We speculate that the most likely reason for the developmental arrest is that the
kel-1 deletion mutants cannot feed effectively. 1. Hayasizaki et al. (1998) Genes to cells 3, 189-202 2. Ohmachi et al. (1998) Midwest worm Meeting Abstract 79