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PLoS One

Title:		Positive selection shaped the convergent evolution of independently expanded kallikrein subfamilies expressed in mouse and rat saliva proteomes
Author(s):		Karn RC; Laukaitis CM;
Address:		"Department of Medicine, College of Medicine, University of Arizona, Tucson, Arizona, United States of America. rkarn@butler.edu"
Journal Title:		PLoS One
Year:		2011
Volume:		20110614
Issue:		6
Page Number:		e20979 -
DOI:		10.1371/journal.pone.0020979
ISSN/ISBN:		1932-6203 (Electronic) 1932-6203 (Linking)
Abstract:		"We performed proteomics studies of salivas from the genome mouse (C57BL/6 strain) and the genome rat (BN/SsNHsd/Mcwi strain). Our goal was to identify salivary proteins with one or more of three characteristics that may indicate that they have been involved in adaptation: 1) rapid expansion of their gene families; 2) footprints of positive selection; and/or 3) sex-limited expression. The results of our proteomics studies allow direct comparison of the proteins expressed and their levels between the sexes of the two rodent species. Twelve members of the Mus musculus species-specific kallikrein subfamily Klk1b showed sex-limited expression in the mouse saliva proteomes. By contrast, we did not find any of the Rattus norvegicus species-specific kallikrein subfamily Klk1c proteins in male or female genome rat, nor transcripts in their submandibular glands. On the other hand, we detected expression of this family as transcripts in the submandibular glands of both sexes of Sprague-Dawley rats. Using the CODEML program in the PAML package, we demonstrate that the two rodent kallikrein subfamilies have apparently evolved rapidly under the influence of positive selection that continually remodeled the amino acid sites on the same face in the members of the subfamilies. Thus, although their kallikrein subfamily expansions were independent, this evolutionary pattern has occurred in parallel in the two rodent species, suggesting a form of convergent evolution at the molecular level. On the basis of this new data, we suggest that the previous speculative function of the species-specific rodent kallikreins as important solely in wound healing in males be investigated further. In addition to or instead of that function, we propose that their sex-limited expression, coupled with their rapid evolution may be clues to an as-yet-undetermined interaction between the sexes"
Keywords:		"Amino Acid Sequence Animals *Evolution, Molecular Female Gene Conversion *Gene Expression Profiling Kallikreins/chemistry/*genetics/metabolism Male Mice Models, Molecular Molecular Sequence Data Pheromones/genetics/metabolism Protein Conformation Proteome;"
Notes:		"MedlineKarn, Robert C Laukaitis, Christina M eng P30 CA023074/CA/NCI NIH HHS/ P50 CA095060/CA/NCI NIH HHS/ CA 023074/CA/NCI NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't 2011/06/23 PLoS One. 2011; 6(6):e20979. doi: 10.1371/journal.pone.0020979. Epub 2011 Jun 14"