Ino80 subfamily
The archetype of the Ino80 subfamily is the Ino80
protein from S cerevisiae. Further members have been
identified by sequence similarity in fungi, plants and
animals 1. Ino80p was first
isolated through its role in transcriptional
regulation of inositol biosynthesis 2, 3 and forms part of
the large Ino80.com complex 4. This complex is
notable not only because it can reposition
nucleosomes, but also because it is the only known
Snf2 family-related complex able to separate DNA
strands in a traditional helicase assay 4. However, the
Ino80 complex contains two RuvB-like helicase
subunits which may assist in strand separation.
The human INO80 complex has recently been shown to
contain many proteins homologous to Ino80.com subunits,
including the RuvB-like helicases, and to be capable of
mobilising mononucleosomes 5.
Ino80p deleted strains are sensitive to DNA damaging
agents, and recent studies have implicated Ino80p
directly in the events of double stranded break repair
6, 7, perhaps for the
eviction of nucleosomes in the vicinity of the break
8. However, other
remodelling complexes such as Swr1, RSC and SWI/SNF
may also be participants in other steps of the
repair pathway (reviewed in 9).
references
1: Bakshi, R., T.
Prakash, et al. (2004). In silico
characterization of the INO80 subfamily of
SWI2/SNF2 chromatin remodeling proteins. Biochem
Biophys Res Commun 320(1): 197-204.
PubMed
2: Bachhawat, N., Q.
Ouyang, et al. (1995). Functional
characterization of an inositol-sensitive
upstream activation sequence in yeast. A
cis-regulatory element responsible for
inositol-choline mediated regulation of
phospholipid biosynthesis. J Biol Chem 270(42):
25087-95.
PubMed
3: Ebbert, R., A.
Birkmann, et al. (1999). The product of the
SNF2/SWI2 paralogue INO80 of Saccharomyces
cerevisiae required for efficient expression of
various yeast structural genes is part of a
high-molecular-weight protein complex. Mol
Microbiol 32(4): 741-51.
PubMed
4: Shen, X., G.
Mizuguchi, et al. (2000). A chromatin
remodelling complex involved in transcription
and DNA processing. Nature 406(6795): 541-4.
PubMed
5: Jin, J., Y. Cai, et
al. (2005). A Mammalian Chromatin Remodeling
Complex with Similarities to the Yeast INO80
Complex. J Biol Chem 280(50): 41207-12.
PubMed
6: Morrison, A. J., J.
Highland, et al. (2004). INO80 and gamma-H2AX
interaction links ATP-dependent chromatin
remodeling to DNA damage repair. Cell 119(6):
767-75.
PubMed
7: van Attikum, H., O.
Fritsch, et al. (2004). Recruitment of the INO80
complex by H2A phosphorylation links
ATP-dependent chromatin remodeling with DNA
double-strand break repair. Cell 119(6): 777-88.
PubMed
8: Tsukuda, T., A. B.
Fleming, et al. (2005). Chromatin remodelling at
a DNA double-strand break site in Saccharomyces
cerevisiae. Nature 438(7066): 379-83.
PubMed
9: Downs, J. A. and J.
Cote (2005). Dynamics of chromatin during the
repair of DNA double-strand breaks. Cell Cycle
4(10): 1373-6.
PubMed
