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Dual targets of a transcriptional activator that tracks on DNA
Author(s) -
Sanders Glenn M.,
Kassavetis George A.,
Geiduschek E. Peter
Publication year - 1997
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 - 10.1093/emboj/16.11.3124
Subject(s) - biology , dna , dual (grammatical number) , computational biology , genetics , transcription (linguistics) , microbiology and biotechnology , linguistics , philosophy , art , literature
The sliding clamp of the bacteriophage T4 DNA polymerase, gp45, is also the proximal effector for activation of transcription of T4 late genes. We have identified the phage T4‐encoded σ factor gp55 and the co‐activator gp33 as targets of gp45 in promoter complexes, and have shown that a conserved carboxy‐terminal amino acid sequence of gp55 and gp33 is required for interaction with gp45. The respective contribution of each target–gp45 interaction to activation of transcription has been assessed by measuring promoter opening rates. The opening rate supported by interaction with both targets is far greater than the arithmetical sum of the separate contributions of each target, implying a synergistic activation of transcription through at least two separate interactions of the trimeric gp45.