Membrane proteins Bqt3 and -4 anchor telomeres to the nuclear envelope to ensure chromosomal bouquet formation.
In many organisms, telomeres cluster to form a bouquet arrangement of chromosomes during meiotic prophase. Previously, we reported that two meiotic proteins, Bqt1 and -2, are required for tethering telomeres to the spindle pole body (SPB) during meiotic prophase in fission yeast. This study has further identified two novel, ubiquitously expressed inner nuclear membrane (INM) proteins, Bqt3 and -4, which are required for bouquet formation. We found that in the absence of Bqt4, telomeres failed to associate with the nuclear membranes in vegetative cells and consequently failed to cluster to the SPB in meiotic prophase. In the absence of Bqt3, Bqt4 protein was degraded during meiosis, leading to a phenotype similar to that of the bqt4-null mutant. Collectively, these results show that Bqt4 anchors telomeres to the INM and that Bqt3 protects Bqt4 from protein degradation. Interestingly, the functional integrity of telomeres is maintained even when they are separated from the nuclear envelope in vegetative cells.
Chikashige
Yuji
Y
Kobe Advanced ICT Research Center, National Institute of Information and Communications Technology, Nishi-ku, Kobe 651-2492, Japan.
Yamane
Miho
M
Okamasa
Kasumi
K
Tsutsumi
Chihiro
C
Kojidani
Tomoko
T
Sato
Mamiko
M
Haraguchi
Tokuko
T
Hiraoka
Yasushi
Y
D015825:Chromosomes, Fungal / Q000378:metabolism* / Q000648:ultrastructure; D017353:Gene Deletion; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016615:Telomere / Q000378:metabolism*
D008565:Membrane Proteins; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins