TRF2 promotes, remodels and protects telomeric Holliday junctions.
The ability of the telomeric DNA-binding protein, TRF2, to stimulate t-loop formation while preventing t-loop deletion is believed to be crucial to maintain telomere integrity in mammals. However, little is known on the molecular mechanisms behind these properties of TRF2. In this report, we show that TRF2 greatly increases the rate of Holliday junction (HJ) formation and blocks the cleavage by various types of HJ resolving activities, including the newly identified human GEN1 protein. By using potassium permanganate probing and differential scanning calorimetry, we reveal that the basic domain of TRF2 induces structural changes to the junction. We propose that TRF2 contributes to t-loop stabilisation by stimulating HJ formation and by preventing resolvase cleavage. These findings provide novel insights into the interplay between telomere protection and homologous recombination and suggest a general model in which TRF2 maintains telomere integrity by controlling the turnover of HJ at t-loops and at regressed replication forks.
Poulet
Anaïs
A
Université de Lyon, Laboratoire de Biologie Moléculaire de la Cellule, CNRS UMR5239, Ecole Normale Supérieure de Lyon, Lyon, France.
Buisson
Rémi
R
Faivre-Moskalenko
Cendrine
C
Koelblen
Mélanie
M
Amiard
Simon
S
Montel
Fabien
F
Cuesta-Lopez
Santiago
S
Bornet
Olivier
O
Guerlesquin
Françoise
F
Godet
Thomas
T
Moukhtar
Julien
J
Argoul
Françoise
F
Déclais
Anne-Cécile
AC
Lilley
David M J
DM
Ip
Stephen C Y
SC
West
Stephen C
SC
Gilson
Eric
E
Giraud-Panis
Marie-Josèphe
MJ
D001419:Bacteria / Q000201:enzymology; D020029:Base Pairing; D001483:Base Sequence; D001681:Biological Assay; D045566:DNA, Cruciform / Q000378:metabolism*; D006639:Histidine / Q000378:metabolism; D045565:Holliday Junction Resolvases / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011196:Potassium Permanganate / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D045522:Recombinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D016615:Telomere / Q000378:metabolism*; D035341:Telomeric Repeat Binding Protein 2 / Q000737:chemistry / Q000378:metabolism*
D045566:DNA, Cruciform; D045522:Recombinases; D035341:Telomeric Repeat Binding Protein 2; D011196:Potassium Permanganate; D006639:Histidine; C533748:GEN1 protein, human; D045565:Holliday Junction Resolvases