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1
Heterochromatin and chromatin regulators
TPE
Position effect variegation (PEV)
white
ADE2
Péricentrique X
télomérique
2
S U(VAR)3-9
Domaine SET
Fonction du domaine SET
Méthyltransférase (spécifique de lhistone H3)
3
Set1p is a H3 K4 methyl transferase
RRM
SET domain
SET1
S. cerevisiae
1081
4
Telomeric chromatin Structure, silencing
Telomere length regulation
Gene expression H3K4 methylation Transcriptional
activation
SET1
Meiosis
DNA repair
5
Curent model H3K4 methylation is required for
telomeric silencing - Mutation of H3 K4R
affects telomeric silencing -inactivation of
rad6, an ubiquitin ligase, abolishes H2B
mono-ubiquitination, H3K4 methylation, and
telomeric silencing (Allis et al., Nature,
2002). Problems with this model ChIP
experiments see next slides
6
Structure of a S.cerevisiae telomere
Sir3
Sir4
Sir2
Histones H3/H4
C1-3A/TG1-3
Rap1 binding sites
7
(No Transcript)
8
HMTase and TPE
URA3
C
TG1-3 / C1-3 A
SGAL - LEU
SGAL- LEU 5-FOA
wt vector wt Set1p wt SET domain set1
vector set1 Set1p set1 SET domain
set1? vector
set1 SET domain
set1? Set1
wt vector
H3mK4
9
(No Transcript)
10
Localization of Sir3p in set1? cells
wt
set1 D
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Localization of Rap1-GFP is affected in set1?
cells
wt
set1?
12
sml1?-T mec1?-ly set1?-K tel1?-le
sml1?-T mec1?-ly set1?-K
sml1?-T tel1?-le
sml1?
tel1?
sml1?-T mec1?-ly tel1?-le
sml1? set1?
sml1?-T set1?-K
set1?-K sml1?-T
set1?-K tel1?-le
sml1?-T mec1?-ly
wt
set1?
7
8
12
13
15
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The set1-associated defect in telomeric
silencing is due to the mislocalization of
Rap1. Our model Set1p affects the
Rap1-localizing factor (Rlf2/Cac1 chromatin
assembly factor1)? The set1-induced defect in
telomeric silencing is upstream H3 K4
methylation.
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RRM
SET domain
SET1
S. cerevisiae
1081
Deletion of the RRM strongly affects H3K4
methylation and telomeric silencing, but also
protein stability.
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Eric Gilson, ENS LYON Ulf Nehrbass, Institut
Pasteur, PARIS Harry Schertann, Institut fur
Biochemie, BERLIN