Biology Reference
In-Depth Information
TABLE II
F
UNCTIONAL
D
OMAINS OF
RSC S
UBUNITS
Subunit
Domains and properties
References
26,27
Sth1
Essential, catalytic subunit containing ATPase domain, has, and
post-HSA domains involved in Arp binding and regulation of
ATPase activity, bromodomain (acetyl-lysine binding)
37
Arp7
Binds as Arp7-Arp9 heterodimer to HSA domain of Sth1
37
Arp9
Binds as Arp7-Arp9 heterodimer to HSA domain of Sth1
Rtt102
Rsc6
34
Essential, binds Rsc8
28
Sfh1
Essential, phosphorylated in G1, binds directly to Sth1
36
Rsc8
Essential, contains weak DNA-binding SWIRM domain
29,30
Rsc3
Essential, sequence-specific DNA binding, heterodimer with highly
similar Rsc30, zinc cluster, QIREY domain, coiled coils
29
Rsc30
Essential, heterodimer with highly similar Rsc30, zinc cluster,
QIREY domain, coiled coils
41
Rsc1 or Rsc2
2 Bromodomains, AT-hook, BAH domain, C-terminal region
required for assembly into complex
31,32
Rsc4
2 Bromodomains, interacts with RNA polymerases
35
Rsc7
Fungal-specific, binds Rsc8
Rsc9
Rsc14
Htl1
38-40
Substoichiometric subunit, binds Rsc8
33
Rsc58
Essential
Additionally, a third class of complex was observed in the mixture of both Rsc1
and Rsc2 isoforms, where part of the bottom arm was missing or had reduced
density. Given that this conformation accounted for
16% of the total popu-
lation of complexes and that Rsc1 is
10% as abundant as Rsc2, it is interesting
to speculate that maybe this conformation is unique to the Rsc1 isoform,
indicating differences either in the structures of the Rsc1 and Rsc2 subunits
or in affinities of other subunits for the two isoforms. Addition of nucleosomes
did not broadly affect the structure of the RSC complexes, but analysis of the
density in the central cavity suggested that alterations had occurred to the
structure of the nucleosome upon its binding to RSC, including loss of H2A-
H2B.
43
Consistent with RSC-dependent changes in nucleosome structure is
the finding that binding to RSC rendered nucleosomal DNA sensitive to
exonuclease III and DNase I.
46,47
B. Biochemical Activity
The biochemical activities of the RSC complex have been examined
in vitro
and have been shown to include nucleosome remodeling, repositioning, disas-
sembly, and histone octamer transfer
.
The ATPase activity of the RSC complex
