Functional diversification of the nematode mbd2/3 gene between Pristionchus pacificus and Caenorhabditis elegans.
BACKGROUND
Several members of the Methyl-Binding Domain protein family link DNA methylation with chromatin remodeling complexes in vertebrates. Amongst the four classes of MBD proteins, MBD2/3 is the most highly conserved and widespread in metazoans. We have previously reported that an mbd2/3 like gene (mbd-2) is encoded in the genomes of the nematodes Pristionchus pacificus, Caenorhabditis elegans and Caenorhabditis briggsae. RNAi knock-down of mbd-2 in the two Caenorhabditis species results in varying percentages of lethality.


RESULTS
Here, we report that a general feature of nematode MBD2/3 proteins seems to be the lack of a bona fide methyl-binding domain. We isolated a null allele of mbd-2 in P. pacificus and show that Ppa-mbd-2 mutants are viable, fertile and display a fully penetrant egg laying defect. This egg laying defect is partially rescued by treatment with acetylcholine or nicotine suggesting a specific function of this protein in vulval neurons. Using Yeast-two-hybrid screens, Ppa-MBD-2 was found to associate with microtubule interacting and vesicle transfer proteins.


CONCLUSIONS
These results imply that MBD2/3 proteins in nematodes are more variable than their relatives in insects and vertebrates both in structure and function. Moreover, nematode MBD2/3 proteins assume functions independent of DNA methylation ranging from the indispensable to the non-essential.
Gutierrez
Arturo
A
Max-Planck Institute for Developmental Biology, Department for Evolutionary Biology, Spemannstrasse 37, D-72076 Tübingen, Germany. gutierre@embl.de
Sommer
Ralf J
RJ
D000818:Animals; D017173:Caenorhabditis elegans / Q000145:classification / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D019175:DNA Methylation; D018509:DNA, Helminth / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D049751:Genome, Helminth; D015801:Helminth Proteins / Q000235:genetics*; D009154:Mutation; D009348:Nematoda / Q000145:classification / Q000235:genetics*; D010058:Oviposition; D017422:Sequence Analysis, DNA; D013045:Species Specificity
D029742:Caenorhabditis elegans Proteins; D018509:DNA, Helminth; D004268:DNA-Binding Proteins; D015801:Helminth Proteins; C115368:MBD2 protein