Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements
<p>Abstract</p> <p>Self splicing introns and inteins that rely on a homing endonuclease for propagation are parasitic genetic elements. Their life-cycle and evolutionary fate has been described through the homing cycle. According to this model the homing endonuclease is selected fo...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2006-11-01
|
| Series: | BMC Evolutionary Biology |
| Online Access: | http://www.biomedcentral.com/1471-2148/6/94 |
| _version_ | 1818975262788812800 |
|---|---|
| author | Hilario Elena Gogarten J Peter |
| author_facet | Hilario Elena Gogarten J Peter |
| author_sort | Hilario Elena |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Self splicing introns and inteins that rely on a homing endonuclease for propagation are parasitic genetic elements. Their life-cycle and evolutionary fate has been described through the homing cycle. According to this model the homing endonuclease is selected for function only during the spreading phase of the parasite. This phase ends when the parasitic element is fixed in the population. Upon fixation the homing endonuclease is no longer under selection, and its activity is lost through random processes. Recent analyses of these parasitic elements with functional homing endonucleases suggest that this model in its most simple form is not always applicable. Apparently, functioning homing endonuclease can persist over long evolutionary times in populations and species that are thought to be asexual or nearly asexual. Here we review these recent findings and discuss their implications. Reasons for the long-term persistence of a functional homing endonuclease include: More recombination (sexual and as a result of gene transfer) than previously assumed for these organisms; complex population structures that prevent the element from being fixed; a balance between active spreading of the homing endonuclease and a decrease in fitness caused by the parasite in the host organism; or a function of the homing endonuclease that increases the fitness of the host organism and results in purifying selection for the homing endonuclease activity, even after fixation in a local population. In the future, more detailed studies of the population dynamics of the activity and regulation of homing endonucleases are needed to decide between these possibilities, and to determine their relative contributions to the long term survival of parasitic genes within a population. Two outstanding publications on the amoeba <it>Naegleria </it>group I intron (Wikmark et al. <it>BMC Evol Biol </it>2006, <b>6:</b>39) and the PRP8 inteins in ascomycetes (Butler et al.<it>BMC Evol Biol </it>2006, <b>6:</b>42) provide important stepping stones towards integrated studies on how these parasitic elements evolve through time together with, or despite, their hosts.</p> |
| first_indexed | 2024-12-20T15:53:10Z |
| format | Article |
| id | doaj.art-0b2b90306ac4491792359f9c1acf93b7 |
| institution | Directory Open Access Journal |
| issn | 1471-2148 |
| language | English |
| last_indexed | 2024-12-20T15:53:10Z |
| publishDate | 2006-11-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Evolutionary Biology |
| spelling | doaj.art-0b2b90306ac4491792359f9c1acf93b72022-12-21T19:34:36ZengBMCBMC Evolutionary Biology1471-21482006-11-01619410.1186/1471-2148-6-94Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elementsHilario ElenaGogarten J Peter<p>Abstract</p> <p>Self splicing introns and inteins that rely on a homing endonuclease for propagation are parasitic genetic elements. Their life-cycle and evolutionary fate has been described through the homing cycle. According to this model the homing endonuclease is selected for function only during the spreading phase of the parasite. This phase ends when the parasitic element is fixed in the population. Upon fixation the homing endonuclease is no longer under selection, and its activity is lost through random processes. Recent analyses of these parasitic elements with functional homing endonucleases suggest that this model in its most simple form is not always applicable. Apparently, functioning homing endonuclease can persist over long evolutionary times in populations and species that are thought to be asexual or nearly asexual. Here we review these recent findings and discuss their implications. Reasons for the long-term persistence of a functional homing endonuclease include: More recombination (sexual and as a result of gene transfer) than previously assumed for these organisms; complex population structures that prevent the element from being fixed; a balance between active spreading of the homing endonuclease and a decrease in fitness caused by the parasite in the host organism; or a function of the homing endonuclease that increases the fitness of the host organism and results in purifying selection for the homing endonuclease activity, even after fixation in a local population. In the future, more detailed studies of the population dynamics of the activity and regulation of homing endonucleases are needed to decide between these possibilities, and to determine their relative contributions to the long term survival of parasitic genes within a population. Two outstanding publications on the amoeba <it>Naegleria </it>group I intron (Wikmark et al. <it>BMC Evol Biol </it>2006, <b>6:</b>39) and the PRP8 inteins in ascomycetes (Butler et al.<it>BMC Evol Biol </it>2006, <b>6:</b>42) provide important stepping stones towards integrated studies on how these parasitic elements evolve through time together with, or despite, their hosts.</p>http://www.biomedcentral.com/1471-2148/6/94 |
| spellingShingle | Hilario Elena Gogarten J Peter Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements BMC Evolutionary Biology |
| title | Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements |
| title_full | Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements |
| title_fullStr | Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements |
| title_full_unstemmed | Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements |
| title_short | Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements |
| title_sort | inteins introns and homing endonucleases recent revelations about the life cycle of parasitic genetic elements |
| url | http://www.biomedcentral.com/1471-2148/6/94 |
| work_keys_str_mv | AT hilarioelena inteinsintronsandhomingendonucleasesrecentrevelationsaboutthelifecycleofparasiticgeneticelements AT gogartenjpeter inteinsintronsandhomingendonucleasesrecentrevelationsaboutthelifecycleofparasiticgeneticelements |