Mural at NASA Ames Research Center
Homing Endonucleases
Sequence nearly identical to the
carrot vma1 gene – except for central
region of about 1200 nucleotides.
Homing
Ribonucleotide Reductase
Intein
Group I Introns
Group II Introns
Inteins
Group I Introns
Group II Introns
Homing cycle of a parasitic genetic element (modified from [3, 13]). Recent findings
suggest that due to complex population structure the cycle might not operate in
synchrony in different subpopulations. The red arrows indicate the trajectory of the
functioning HE and the black arrows the fate of the host gene. The precise loss can
occur through recombination with an intein or intron free allele, or, in case of introns,
through recombination with a reverse transcript of the spliced mRNA [39, 40].
From: Gogarten et al., Annu. Rev. Microbiol. 2002. 56:263–87
X
Alleles with empty
Target Site
Y
Alleles harboring a
dysfunctional
Homing
Endonuclease
Y>Z
(II) Carriers of the Y-allele are
more fit than carriers of the Z
allele.
The presence of a dysfunctional
homing endonuclease provides
immunity to invasion by Z
Z
Alleles invaded by a
functional Homing
Endonuclease
Long term persistence
of the HE containing
allele is possible within
a single well mixed
population. Different
trajectories result
depending on the size
of the selective
disadvantage caused by
the functioning HE and
the frequency of efficient
homing.
Collaboration with Adi
Barzel, Uri Obolski,
Martin Kupiec, Lilach
Hadany from Tel Aviv
University