Structure of bacteriophage T7. Small-angle X-ray and neutron scattering study

Abstract

Small-angle x-ray and neutron scattering techniques were applied to bacteriophage T7 solutions at different scattering densities. Scattering curves determined under a variety of experimental conditions were used to derive a set of parameters characterizing the shape, size, and weight of the whole phage particle and of its DNA and protein components. The T7 head has an icosahedral shape with an edge of 37.7 +/- 0.5 nm, a volume of (12.0 +/- 1.0) x 10(4) nm3, and a small tail amounting to 6--7% of the head volume. The intraphage DNA region is most probably a hollow sphere. The best fit to the data was obtained with a model in which the hollow sphere filled with a protein core with a diameter of 24 nm. The average degree of swelling (i.e., the ratio of the hydrated to the dry volume) of the particle is 2.3; the degree of swelling of the DNA component is higher, 3.2, and that of the protein part is lower, 1.2.

Solar UV Irradiation Conditions on the Surface of Mars¶

“…Preparation and exposure of the biological dosimeters are described by Rontó et al (24) and Kerékgyártó et al (46). Bacteriophage T7 consists of a small DNA molecule (approximately 40 000 base pairs) with a protein core and envelope (47). The photobiological end‐point of the DNA damage is the phage killing that can be characterized by the survival rate N / N 0 , where N and N 0 are the number of living phage particles after and before irradiation, respectively.…”

DNA damage under simulated extraterrestrial conditions in bacteriophage T7

“…In vivo, the DNA is normally tightly compacted into chromatin via association with histone and non-histon proteins (Goodsell, 1991). Phage T7 contains a doublestranded DNA packed in a superhelical structure between a protein shell and core (Fekete et al, 1982;Rontó et al, 1983), that resembles to the nucleosome DNA structure, the presence of bound phage proteins determines the DNA conformation. The structural changes in the UV spectra upon dehydration have been found almost perfectly reversible ( Fig.…”

Simulation experiments of the effect of space environment on bacteriophage and DNA thin films

“…In vivo, the DNA is normally tightly compacted into chromatin via association with histone and nonhiston proteins (Travers, 1994). Phage T7 contains a double-stranded DNA packed in a superhelical structure between the protein shell and the core (Fekete et al, 1982;Ronto et al, 1983) that resembles the chromosomal DNA arrangement in mammalian cells. Hence, it can be used as a chromosome model from point of view of responses to space parameters.…”