Premium
Evolution of discrete Notch‐like receptors from a distant gene duplication in Caenorhabditis
Author(s) -
Rudel David,
Kimble Judith
Publication year - 2002
Publication title -
evolution and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 78
eISSN - 1525-142X
pISSN - 1520-541X
DOI - 10.1046/j.1525-142x.2002.02027.x
Subject(s) - biology , caenorhabditis elegans , rna interference , caenorhabditis , gene , mutant , genetics , gene duplication , receptor , microbiology and biotechnology , rna
SUMMARY Caenorhabditis elegans possesses two Notch‐like receptors, LIN‐12 and GLP‐1, which have both overlapping and individual biological functions. We examined the lin‐12 and glp‐1 genes in closely related nematodes to learn about their evolution. Here we report molecular and functional analyses of lin‐12 orthologs from two related nematodes, C. briggsae (Cb) and C. remanei (Cr). In addition, we compare these lin‐12 findings with similar studies of Cb‐glp‐1 and Cr‐glp‐1 orthologs. Cb‐LIN‐12 and Cr‐LIN‐12 retain the same number and order of motifs as Ce‐LIN‐12. Intriguingly, we find that LIN‐12 conservation differs from that of GLP‐1 in two respects. First, individual motifs are conserved to a different degree for the two receptors. For example, the transmembrane domain is 16–32% identical among LIN‐12 orthologs but 65–70% identical among GLP‐1 orthologs. Second, certain amino acids are conserved in a receptor‐specific manner, a phenomenon most prevalent in the CC‐linker. We suggest that LIN‐12 and GLP‐1 have been molded by selective constraints that are receptor specific and that the two proteins may not be entirely interchangeable. To analyze the functions of the lin‐12 orthologs, we used RNA‐mediated interference (RNAi). Cb‐lin‐12(RNAi) or Cr‐lin‐12(RNAi) progeny are nearly 100% Lag, a larval lethality typical of C. elegans lin‐12 glp‐1 double mutants, but not the primary defect observed in Ce‐lin‐12 null mutants or Ce‐lin‐12(RNAi). Therefore, LIN‐12 functions are similar, but not identical, among the Caenorhabditis species. We suggest that ancestral functions may have been divided between LIN‐12 and GLP‐1 receptors in a process contributing to the retention of both genes after gene duplication (i.e., subfunctionalization).