Molecular visualization of immunoglobulin switch region RNA/DNA complex by atomic force microscope.
Immunoglobulin heavy-chain (IgH) class switch recombination (CSR) is initiated by DNA breakage in the switch (S) region featuring tandem repetitive nucleotide sequences. Various studies have demonstrated that S-region transcription and splicing proceed to genomic recombination and are indispensable for CSR in vivo, although the precise molecular mechanism is largely unknown. Here, we show the novel physical property of the in vitro transcribed S-region RNA by direct visualization using an atomic force microscope (AFM). The S-region sense RNA, but not the antisense RNA, forms a persistent hybrid with the template plasmid DNA and changes the plasmid conformation from supercoil to open circle in the presence of spermidine. In addition, the S-region transcripts generate globular forms and are assembled on the template DNA into a large aggregate that may stall replication and increase the recombinogenicity of the S-region DNA.
Mizuta
Ryushin
R
Research Institute for Biological Sciences, Tokyo University of Science, 2669 Yamazaki, Noda, Chiba 278-0022, Japan. mizuta@rs.noda.tus.ac.jp
Iwai
Kousuke
K
Shigeno
Masatsugu
M
Mizuta
Midori
M
Uemura
Takeshi
T
Ushiki
Tatsuo
T
Kitamura
Daisuke
D
D017578:Immunoglobulin Class Switching; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000737:chemistry / Q000235:genetics* / Q000648:ultrastructure*; D012313:RNA / Q000737:chemistry / Q000235:genetics* / Q000648:ultrastructure*; D014158:Transcription, Genetic
D012313:RNA