Bacteriophage T7 helicase/primase proteins form rings around single-stranded DNA that suggest a general structure for hexameric helicases - PubMed (original) (raw)

Bacteriophage T7 helicase/primase proteins form rings around single-stranded DNA that suggest a general structure for hexameric helicases

E H Egelman et al. Proc Natl Acad Sci U S A. 1995.

Abstract

Most helicases studied to date have been characterized as oligomeric, but the relation between their structure and function has not been understood. The bacteriophage T7 gene 4 helicase/primase proteins act in T7 DNA replication. We have used electron microscopy, three-dimensional reconstruction, and protein crosslinking to demonstrate that both proteins form hexameric rings around single-stranded DNA. Each subunit has two lobes, so the hexamer appears to be two-tiered, with a small ring stacked on a large ring. The single-stranded DNA passes through the central hole of the hexamer, and the data exclude substantial wrapping of the DNA about or within the protein ring. Further, the hexamer binds DNA with a defined polarity as the smaller ring of the hexamer points toward the 5' end of the DNA. The similarity in three-dimensional structure of the T7 gene 4 proteins to that of the Escherichia coli RuvB helicase suggests that polar rings assembled around DNA may be a general feature of numerous hexameric helicases involved in DNA replication, transcription, recombination, and repair.

PubMed Disclaimer

Cited by

Two Distinct Modes of DNA Binding by an MCM Helicase Enable DNA Translocation.
Meagher M, Myasnikov A, Enemark EJ. Meagher M, et al. Int J Mol Sci. 2022 Nov 24;23(23):14678. doi: 10.3390/ijms232314678. Int J Mol Sci. 2022. PMID: 36499022 Free PMC article.
The enzymatic basis of processivity in lambda exonuclease.
Subramanian K, Rutvisuttinunt W, Scott W, Myers RS. Subramanian K, et al. Nucleic Acids Res. 2003 Mar 15;31(6):1585-96. doi: 10.1093/nar/gkg266. Nucleic Acids Res. 2003. PMID: 12626699 Free PMC article.
The Methanobacterium thermoautotrophicum MCM protein can form heptameric rings.
Yu X, VanLoock MS, Poplawski A, Kelman Z, Xiang T, Tye BK, Egelman EH. Yu X, et al. EMBO Rep. 2002 Aug;3(8):792-7. doi: 10.1093/embo-reports/kvf160. Epub 2002 Jul 15. EMBO Rep. 2002. PMID: 12151340 Free PMC article.
Hexameric RSF1010 helicase RepA: the structural and functional importance of single amino acid residues.
Ziegelin G, Niedenzu T, Lurz R, Saenger W, Lanka E. Ziegelin G, et al. Nucleic Acids Res. 2003 Oct 15;31(20):5917-29. doi: 10.1093/nar/gkg790. Nucleic Acids Res. 2003. PMID: 14530440 Free PMC article.
Mechanisms of a ring shaped helicase.
Donmez I, Patel SS. Donmez I, et al. Nucleic Acids Res. 2006;34(15):4216-24. doi: 10.1093/nar/gkl508. Epub 2006 Aug 25. Nucleic Acids Res. 2006. PMID: 16935879 Free PMC article. Review.

References

1. J Biol Chem. 1992 Jul 25;267(21):15013-21 - PubMed
1. J Biol Chem. 1992 Jul 15;267(20):14129-37 - PubMed
1. Proc Natl Acad Sci U S A. 1993 Feb 15;90(4):1315-9 - PubMed
1. Science. 1993 Apr 2;260(5104):53-8 - PubMed
1. Science. 1993 Apr 2;260(5104):58-63 - PubMed

Bacteriophage T7 helicase/primase proteins form rings around single-stranded DNA that suggest a general structure for hexameric helicases - PubMed (original) (raw)