Imperfect CAG repeats form diverse structures in SCA1 transcripts.
The expanded CAG repeat in the coding sequence of the spinocerebellar ataxia type 1 (SCA1) gene is responsible for SCA1, one of the hereditary human neurodegenerative diseases. In the normal SCA1 alleles usually 1-3 CAT triplets break the continuity of the CAG repeat tracts. Here we show what is the structural role of the CAU interruptions in the SCA1 transcripts. Depending on their number and localization within the repeat tract the interruptions either enlarge the terminal loop of the hairpin formed by the repeats, nucleate the internal loops in its stem structure, or force the repeats to fold into two smaller hairpins. Thus, the interruptions destabilize the CAG repeat hairpin, which is likely to decrease its ability to participate in the putative RNA pathogenesis mechanism driven by the long CAG repeat hairpins.
Sobczak
Krzysztof
K
Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
Krzyzosiak
Wlodzimierz J
WJ
D000483:Alleles; D000067696:Ataxin-1; D000067528:Ataxins; D001483:Base Sequence; D005347:Fibroblasts; D006801:Humans; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D009690:Nucleic Acid Conformation; D012333:RNA, Messenger; D020754:Spinocerebellar Ataxias / Q000209:etiology / Q000235:genetics; D018911:Trinucleotide Repeats
C000593749:ATXN1 protein, human; D000067696:Ataxin-1; D000067528:Ataxins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger