Molecular Evolution of a Sex Determination Protein: FEM-2 (PP2C) in Caenorhabditis
Date
1998-04
Authors
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Journal ISSN
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Publisher
Genetics Society of America
Abstract
Somatic sex determination in Caenorhabditis elegans involves a signal transduction pathway linking a
membrane receptor to a transcription factor. The fem-2 gene is central to this pathway, producing a protein
phosphatase (FEM-2) of the type 2C (PP2C). FEM-2 contains a long amino terminus that is absent in
canonical PP2C enzymes. The function of this domain is difficult to predict, since it shows no sequence
similarity to any other known proteins or motifs. Here we report the cloning of the fem-2 homologue from
Caenorhabditis briggsae (Cb-fem-2). The sequence identity is much higher than that observed for other
C. briggsae homologues of C. elegans sex determination proteins. However, this level is not uniform across
the entire lengths of the proteins; it is much lower in the amino termini. Thus, the two domains of the
same protein are evolving at different rates, suggesting that they have different functional constraints.
Consistent with this, Cb-FEM-2 is able to replace some, but not all, of the Ce-FEM-2 in vivo function. We
show that removal of the amino terminus from Ce-FEM-2 has no effect on its in vitro phosphatase activity,
or its ability to replace the in vivo function of a yeast PP2C enzyme, but that it is necessary for proper
FEM-2 function in worms. This demonstrates that the amino terminus is not an extended catalytic domain
or a direct negative regulator of phosphatase activity.
Description
Copyright © 2006 by the Genetics Society of America. http://www.genetics.org/
Keywords
Biology
Citation
Dave Hansen, Dave Pilgrim "Molecular Evolution of a Sex Determination Protein: FEM-2 (PP2C) in Caenorhabditis" Genetics 149: 1353–1362 ( July 1998)