Gene transfer agent
A gene transfer agent (GTA) is a bacteriophage-like element produced by several bacteria that mediates horizontal gene transfer. GTAs package random segments of DNA present in the host bacterium, which can be transduced to a recipient cell.
The model-GTA is the RcGTA produced by the alphaproteobacterium Rhodobacter capsulatus. When cultured in laboratory conditions, a subset of the bacterial population induces production of RcGTA upon entry into stationary phase, which are subsequently released from the cells through cell lysis. Most of the RcGTA structural genes are encoded in a ~ 15 kb genetic cluster on the bacterial chromosome. However, other genes required for RcGTA function, such as the genes required for RcGTA release through cell lysis are located separately. Production of RcGTA appears to be controlled by the host cell, because several host systems, including a quorum sensing system and a histidine kinase and response regulator  are required for RcGTA-transduction. Furthermore, the ability of cells to receive genetic material transduced by RcGTA requires a capsular polysaccharide receptor, which is regulated by the quorum sensing system.
RcGTA-like clusters are found in several alphaproteobacteria. Recently, several members of the order Rhodobacterales have been demonstrated to produce functional RcGTA-like particles. In addition to the RcGTA-like GTAs, several other GTAs with no homology to RcGTA have been described. Of these, the best studied is VSH-1 produced by the spirochaete Brachyspira hyodysenteriae.
- Fogg, P. C. M.; Westbye, A. B.; Beatty, J. T. (2012). Banfield, Bruce W, ed. "One for All or All for One: Heterogeneous Expression and Host Cell Lysis Are Key to Gene Transfer Agent Activity in Rhodobacter capsulatus". PLoS ONE. 7 (8): e43772. Bibcode:2012PLoSO...743772F. PMC . PMID 22916305. doi:10.1371/journal.pone.0043772.
- Lang, A. S.; Zhaxybayeva, O.; Beatty, J. T. (2012). "Gene transfer agents: Phage-like elements of genetic exchange". Nature Reviews Microbiology. 10: 472–82. PMC . PMID 22683880. doi:10.1038/nrmicro2802.
- Westbye, A. B.; Leung, M. M.; Florizone, S.; Taylor, T. A.; Johnson, J. A.; Fogg, P. C.; Beatty, J. T. (2013). "Phosphate concentration and the putative sensor-kinase protein CckA modulate cell lysis and release of the Rhodobacter capsulatus gene transfer agent (RcGTA)". Journal of Bacteriology. 195: 5025–40. PMC . PMID 23995641. doi:10.1128/JB.00669-13.
- Brimacombe, C. A.; Stevens, A.; Jun, D.; Mercer, R.; Lang, A. S.; Beatty, J. T. (2013). "Quorum-sensing regulation of a capsular polysaccharide receptor for theRhodobacter capsulatusgene transfer agent (RcGTA)". Molecular Microbiology. 87 (4): 802–817. PMC . PMID 23279213. doi:10.1111/mmi.12132.
- Lang, AS and Beatty, JT (2007) "Importance of widespread gene transfer agent genes in alpha-proteobacteria." Trends in Microbiology, 15(2) pp. 54–62. (Review)
- McDaniel, L. D.; Young, E.; Delaney, J.; Ruhnau, F.; Ritchie, K. B.; Paul, J. H. (2010). "High Frequency of Horizontal Gene Transfer in the Oceans". Science. 330 (6000): 50. Bibcode:2010Sci...330...50M. PMID 20929803. doi:10.1126/science.1192243.
- Maxmen, A. (2010). "Virus-like particles speed bacterial evolution". Nature. doi:10.1038/news.2010.507.
- Stanton, TB (2007) "Prophage-like gene transfer agents-novel mechanisms of gene exchange for Methanococcus, Desulfovibrio, Brachyspira, and Rhodobacter species." Anaerobe, 13(2) pp. 43–49. (Review)