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.[1] 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.[2][3] 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 [2] 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.[4]
RcGTA-like clusters are found in several alphaproteobacteria.[5] Recently, several members of the order Rhodobacterales have been demonstrated to produce functional RcGTA-like particles.[6][7] 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.[8]
See also
References
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- ↑ 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)
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- ↑ 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)