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Transposon‐like properties of the major, long repetitive sequence family in the genome of Physarum polycephalum
Author(s) -
Pearston Douglas H.,
Gordon Mairi,
Hardman Norman
Publication year - 1985
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1985.tb04117.x
Subject(s) - physarum polycephalum , physarum , biology , library science , computer science , botany
A family of long, highly‐repetitive sequences, referred to previously as ‘ Hpa II‐repeats’, dominates the genome of the eukaryotic slime mould Physarum polycephalum . These sequences are found exclusively in scrambled clusters. They account for about one‐half of the total complement of repetitive DNA in Physarum , and represent the major sequence component found in hypermethylated, 20‐50 kb segments of Physarum genomic DNA that fail to be cleaved using the restriction endonuclease Hpa II. The structure of this abundant repetitive element was investigated by analysing cloned segments derived from the hypermethylated genomic DNA compartment. We show that the ‘ Hpa II‐repeat’ forms part of a larger repetitive DNA structure, ∼8.6 kb in length, with several structural features in common with recognised eukaryotic transposable genetic elements. Scrambled clusters of the sequence probably arise as a result of transposition‐like events, during which the element preferentially recombines in either orientation with target sites located in other copies of the same repeated sequence. The target sites for transposition/recombination are not related in sequence but in all cases studied they are potentially capable of promoting the formation of small ‘cruciforms’ or ‘Z‐DNA’ structures which might be recognised during the recombination process.