Mechanisms of Positive Selection on Gamete Recogntion Proteins

Louisiana State University, Baton Rouge LA

Investigators

Abstract

0075382 Hellberg Proteins associated with male reproductive function typically evolve much faster than other proteins. In marine invertebrates that release their eggs and sperm directly into seawater, these male proteins, along with their egg-borne female complements, determine whether individuals and species can interbreed. Natural selection is known to promote the divergence of these male proteins between species; however, the mechanisms causing this selection--particularly the role of functionally related female proteins--remain unknown. Dr. Hellberg will evaluate proposed mechanisms for selection on the sperm protein lysin by comparing DNA sequences of the genes encoding lysin and its egg-borne receptor (VERL) from different species of the marine snail Tegula. VERL contains about 30 internal repeats of 150 amino acids, but sequences for flanking regions at the beginning and end of this protein are not known. Using molecular methods, the PI will determine DNA sequence information for VERL. He will then compare patterns of this sequence data among different species of Tegula. Patterns of VERL variation should illuminate mechanisms causing rapid change in gamete recognition proteins, in turn broadening our understanding of adaptive molecular change in general and the evolution of new, reproductively isolated species in particular. In addition, co-evolution between VERL and lysin may provide insights into the design of highly specific molecular glues (which like VERL are often composed of repeated molecular sequences).