Submitted to: Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 3, 2008
Publication Date: December 31, 2008
Citation: Rooney, A.P., Ward, T.J. 2008. Birth-and-Death Evolution of the Internalin Multigene Family in Listeria. Gene. 427(1-2):124-128. Interpretive Summary: Gene families are defined as groups of functionally related genes. Because they form a large component of the genome, it is important to understand aspects of gene family structure and organization if we are to fully understand genome structure and organization. This paper covers the processes and mechanisms that shape the structure and organization of the internalin gene family in the bacterial foodborne pathogen Listeria monocytogenes. The results of our study show that the internalin gene family is shaped by birth-and-death processes with some instances of lateral gene transfer. The knowledge gained from this study will help our understanding of genes contributing to the pathogencity of an important foodborne pathogen.
Technical Abstract: The birth-and-death model of multigene family evolution has been extensively characterized in eukaryotes over the last decade. However, this mode of multigene family evolution has not been described for bacteria. By not considering the birth-and-death mode of gene family evolution, the extent of lateral transfer events may be artificially projected upwards. The purpose of this study was to investigate whether this holds true in a representative bacterial multigene family, the internalins. Our findings indicate that internalins evolve under a birth-and-death process. Lateral transfer was detected twice, but the estimated frequency would have been much higher had it not been analyzed within the context of birth-and-death evolutionary dynamics and a phenomenon that we term “gene duplicate-sorting”, which involves the unequal transmittal of gene duplicates during or subsequent to the speciation process. Within this framework, we suggest that the frequency of lateral transfer in bacterial multigene families may be artificially inflated and that its extent should be reinterpreted in the light of birth-and-death evolution.