A Model for the Complex Between the Helix Destabilizing Protein GP32 of Bacteriophage T4 and Single-Stranded DNA

Abstract

A model for the structure of the complex between the helix-destabilizing protein of bacteriophage T4, GP32, and single-stranded DNA is proposed. In this model the bases are arranged in a helix, that is characterized by a relatively large distance between successive bases, a substantial base tilt, in combination with a small rotation per base. This helix is further organized into a tertiary structure, possibly a superhelix, of which the corresponding protein shell corresponds to the relatively rigid and rod-like structure that is observed in hydrodynamic experiments. It is proposed that similar structural features apply to other single-stranded DNA binding proteins in complex with polynucleotides.

Visualization of the Annealing of Complementary Single-stranded DNA Catalyzed by the Herpes Simplex Virus Type 1 ICP8 SSB/Recombinase

“…The T4 gene 32 protein has been reported to form a complex with ssDNA in which the helix diameter is large and the bases are almost parallel with the helix axis, and it was suggested that the helix may be further organized into a tertiary structure, possibly a superhelix corresponding to a relatively rigid and rod-like structure. 50,51 We have shown that the annealing of complementary ssDNA induced by ICP8 takes place through the formation of intertwined coiled-coils. A model of this process is presented in Figure 8.…”

Study of the binding of single-stranded DNA-binding protein to DNA and poly(rA) using electric field induced birefringence and circular dichroism spectroscopy

“…Moreover, an increased local base-base distance is characteristic for the complexed DNA (Scheerhagen, 1986;Scheerhagen et al, 1989;van Amerongen et al, 1987Amerongen et al, , 1990a van Amerongen & van . These properties may be related to the primary functions of these proteins: destabilizing double-helical hairpins, protection of singlestranded DNA from nucleases, and a positive stimulation of the cognate polymerase.…”

“…These structures are characterized by an increased base-base distance, a substantial tilt of the bases, a low rotation per base, and/or a positioning of the bases close to the local helix axis in the complex (Scheerhagen et al, 1986(Scheerhagen et al, , 1989van Amerongen et al, 1988;van Amerongen, 1989).…”

Structure and function of the bacteriophage T4 DNA polymerase holoenzyme

“…The molecular mechanism by which gp32 promotes higher fidelity and processivity is not clear. The observation that gp32 affects the structure of single-stranded DNA, possibly by extending the sugar-phosphate backbone (Scheerhagen et al, 1989;van Amerongenet al, 1990) may be related to these activities of this protein.…”