Chromosome looping in yeast: telomere pairing and coordinated movement reflect anchoring efficiency and territorial organization.
Long-range chromosome organization is known to influence nuclear function. Budding yeast centromeres cluster near the spindle pole body, whereas telomeres are grouped in five to eight perinuclear foci. Using live microscopy, we examine the relative positions of right and left telomeres of several yeast chromosomes. Integrated lac and tet operator arrays are visualized by their respective repressor fused to CFP and YFP in interphase yeast cells. The two ends of chromosomes 3 and 6 interact significantly but transiently, forming whole chromosome loops. For chromosomes 5 and 14, end-to-end interaction is less frequent, yet telomeres are closer to each other than to the centromere, suggesting that yeast chromosomes fold in a Rabl-like conformation. Disruption of telomere anchoring by deletions of YKU70 or SIR4 significantly compromises contact between two linked telomeres. These mutations do not, however, eliminate coordinated movement of telomere (Tel) 6R and Tel6L, which we propose stems from the territorial organization of yeast chromosomes.
Bystricky
Kerstin
K
Department of Molecular Biology and NCCR Frontiers in Genetics, University of Geneva, 1211 Geneva 4, Switzerland.
Laroche
Thierry
T
van Houwe
Griet
G
Blaszczyk
Marek
M
Gasser
Susan M
SM
D002466:Cell Nucleolus / Q000502:physiology; D002467:Cell Nucleus / Q000502:physiology; D015825:Chromosomes, Fungal / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics; D036681:Fluorescence Recovery After Photobleaching; D016193:G1 Phase / Q000502:physiology; D017353:Gene Deletion; D005838:Genotype; D007399:Interphase / Q000502:physiology; D008164:Luminescent Proteins / Q000235:genetics; D008856:Microscopy, Fluorescence; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000235:genetics; D008941:Spindle Apparatus / Q000502:physiology; D016615:Telomere / Q000502:physiology*
D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C061573:SIR4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; C520769:YKU70 protein, S cerevisiae; C081647:high affinity DNA-binding factor, S cerevisiae; C034811:tetracycline resistance-encoding transposon repressor protein