DIVERSITY AND FUNCTIONAL RELEVANCE OF ANTIMICROBIAL PEPTIDE EXPRESSED GENE SEQUENCES IN SHRIMP

¹ Marine Biomedicine and Environmental Sciences, Medical University of South Carolina, Charleston SC

² Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston SC 29425

As critical components of the innate immune system antimicrobial peptides (AMP) constitute the first line of defense against a wide range of potential pathogens in an ever changing environment. Penaeidins are a diverse family of AMP originally characterized in a Pacific shrimp species, Litopenaeus vannamei, which are known to target bacteria and fungi. Analysis of expressed gene sequences from several species of shrimp reveals that multiple classes of penaeidins are expressed in each species that has been examined thus far and that these classes are present and expressed in individual shrimp. We have characterized the penaeidin genes with the goal of defining the source of penaeidin diversity through a deductive manner by comparing expressed sequences with their genomic blueprints. Independently we have also used chemical synthesis methods to generate mature penaeidin peptides deduced from expressed sequences in order to validate the function of novel penaeidin sequences with unknown function. Exploring penaeidin diversity at the functional level (antimicrobial activity) has revealed that functional diversity accompanies variability in expressed gene sequences and characterization of the structure of the genes encoding the penaeidin message has revealed some unique characteristics of penaeidin organization in the shrimp genome.