Organization of the macronuclear gene-sized pieces of stichotrichous ciliates into a higher order structure via telomere-matrix interactions.
Macronuclear DNA of stichotrichous ciliates occurs in small 'gene-sized' molecules with sizes of about 0.5 to 40 kb. Each of these molecules is terminated by telomeric sequences of defined length. A single macronucleus contains up to 10(8) DNA molecules; due to the high concentration of telomeric sequences in this nucleus it is an attractive model to study telomere behaviour. We recently provided evidence that macronuclear telomeres are attached to the nuclear matrix and that this interaction is mediated by the telomere binding protein (TeBP). Using various experimental approaches, we now demonstrate that telomeres as well as both subunits of the telomere binding protein are associated with the nuclear matrix. However, there is no direct binding of telomeric DNA to the matrix but telomere matrix interaction is exclusively mediated by the TeBP. In addition, we show that telomeric sequences adopt in vivo the antiparallel G-quartet structure when bound to the nuclear matrix. These data not only allow us to propose a model for macronuclear architecture but may also be relevant for further analysis of telomere-matrix interactions in higher eukaryotes.
Jönsson
Franziska
F
Institute of Cell Biology, University Witten/Herdecke, Stockumer Str. 10, D-58448 Witten, Germany.
Postberg
Jan
J
Schaffitzel
Christiane
C
Lipps
Hans J
HJ
D000818:Animals; D002455:Cell Division / Q000502:physiology; D017931:DNA Primers / Q000737:chemistry; D016054:DNA, Protozoan / Q000032:analysis; D016810:Hypotrichida / Q000502:physiology*; D017404:In Situ Hybridization, Fluorescence; D008958:Models, Molecular; D015530:Nuclear Matrix / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D021122:Protein Subunits; D015800:Protozoan Proteins / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D016615:Telomere / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D016054:DNA, Protozoan; D021122:Protein Subunits; D015800:Protozoan Proteins; D034501:Telomere-Binding Proteins