On the solution structure of the T4 sliding clamp (gp45)

David Millar, Michael A. Trakselis, Stephen J. Benkovic

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Examination by time-resolved fluorescence spectroscopy of the trimeric bacteriophage T4 clamp protein labeled across its three subunit interfaces with a fluorescence resonance energy transfer (FRET) pair indicates that the clamp exists in just one state in solution, with one open and two closed interfaces. This is in contrast to what is observed in the X-ray crystal structure. The population distribution of the trFRET distance is bimodal, giving 67% as 17 Å and 33% as 42 Å. This leads to the conclusion that gp45 exists in an asymmetric open state in solution. The further increase in the separation of the FRET pair in the presence of the clamp loader and ATP may be ascribed to either further opening of the open interface or the opening of a closed interface. The ramifications for replisome remodeling by this pathway are discussed.

Original languageEnglish (US)
Pages (from-to)12723-12727
Number of pages5
Issue number40
StatePublished - Oct 12 2004

All Science Journal Classification (ASJC) codes

  • Biochemistry


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