Submitted to: Anaerobe
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 26, 2007
Publication Date: April 4, 2007
Citation: Stanton, T.B. 2007. Prophage-like gene transfer agents-novel mechanisms of gene exchange for Methanococcus, Desulfovibrio, Brachyspira, and Rhodobacter species. Anaerobe. 13(2):43-49. Technical Abstract: Genome sequencing projects have revealed a remarkable diversity and distribution of prophage (bacteriophage) gene clusters inserted into the genomes of both free-living and host-associated bacteria. The gene clusters represent both functional, lysogenizing bacteriophages and non-functional phage-like elements. Non-functional or “cryptic” prophages are incapable of self-replication. Although they resemble genetic fossils, cryptic prophages can provide biological functions and fitness advantages to their bacterial hosts. One type of cryptic prophage, the prophage-like Gene Transfer Agent or “GTA”, is a mechanism of horizontal gene transfer. GTAs normally package bacterial genome fragments. A population of GTA particles contains the entire host genome and is able to transmit any gene in that genome between cells of the bacterial host. The DNA content of a GTA particle is too small to encode its own genome. They are incapable, therefore, of packing their own genome into a single particle. Although defective for self-propagation, GTAs are the consummate mechanisms of generalized transduction. GTAs have been reported in species of Brachyspira, Methanococcus, Desulfovibrio, and Rhodobacter (Table). The existence of GTAs in these ecologically diverse, phylogenetically distinct bacteria implies that GTAs may be more common in nature than is now appreciated. It is hoped that this review will serve not only as a source of information on GTAs but also an incentive for research both to further characterize the GTAs of Methanococcus and Desulfovibrio species and to search more broadly for GTAs among other anaerobic species.