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Intron‐associated splicing reactions in bacteriophage T4
Author(s) -
Maley F.,
Chu F. K.,
Maley G. F.
Publication year - 1990
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1990.tb00659.x
Subject(s) - intron , biology , rna splicing , group i catalytic intron , group ii intron , exon , gene , genetics , endonuclease , homing endonuclease , rna
Summary Group I introns are present in at least three bacteriophage T4 genes: td, nrdB and sunY. The transcription products of these three genes have similar intron consensus regions and secondary structures, which render them capable of guanosine‐mediated in vitro autocatalytic splicing reactions. Moreover, it has been shown that the 245‐amino‐acid protein encoded in the td intron expresses an endonuclease that cleaves near the joining site for the two exons in the intron‐deleted thymidylate synthase gene. The intron‐containing td gene is resistant to the enzyme. As in the case of other group I intron‐containing genes that have been described in eukaryotes, which also encode site‐specific endonucleases, the td intron is highly mobile and can insert into the intronless td gene by a process initiated by endonuclease cleavage near the insertion site. Whether intron transposition reactions have any physiological significance to the phage, or represent an early imprint on the evolution of introns, remains to be determined.