Dimensions of Xf virus from its rotational and translational diffusion coefficients

Abstract

Measurements on monodisperse preparations of the filamentous virus Xf give 17.3 +/- 0.6 s-1 for its rotational diffusion coefficient in 1 mM sodium phosphate, pH 7.5 at 20 degrees C and (2.53 +/- 0.06) X 10(-8) cm2 s-1 for its translational diffusion coefficient in 0.15 M NaCl and 0.015 M sodium phosphate, pH 7, at 25 degrees C. These coefficients yield a length of 980 +/- 30 nm and a diameter of 7.2 +/- 1.5 nm for the virus in solution when used to solve simultaneously the two Broersma equations for the diffusion of rigid rods.

An electrostatic spatial resonance model for coaxial helical structures with applications to the filamentous bacteriophages

“…(cl)t g P/g virus (Wiseman and Day, 1977), corrected for sequence (c); (c2) mass-per-length, STEM (Reisberg, 1989) (c); and (c3) 2AzDNA/Azp, from c-spacing and EM length (wet virus) Chen et al, 1980). (dl)t N/P mol ratio, and (d2)t g P/g virus (Wiseman and Day, 1977); (d3) mass-per-length, STEM (Reisberg, 1989); (d4) spectral regression (Kostrikis et al, 1994); (d5) and (d6) 2AzDNA/Azpro from c-spacing and EM length (dry virus) Wiseman et al, 1976).…”

DNA packing in the filamentous viruses fd, Xf, Pfl and Pf3

“…The circular DNA molecule extends from one end of its virion to the other and back again, so there are two antiparallel DNA chains. By dividing virus lengths by half the number of nucleotides in the DNAs, one obtains axial nucleotide translations of only 0.23 nm for Pf3, about 0.27 nm for fd and Xf, and more than 0.53 nm for Pfl (11)(12)(13)(14)(15)(16)(17). Probable ratios of two nucleotides per protein subunit in Xf and one nucleotide per subunit in Pfl (11,17) seem to imply that the DNA helix in each of these two viruses has the same pitch as its helix of protein subunits (11,18).…”

Hydrodynamic determination of molecular weight, dimensions, and structural parameters of Pf3 virus

“…The samples were spun at 5000g for 1 h to remove particulates, transferred to the birefringence cell, and degassed before a run commenced. All measurements were made at 24.75 f 0.05 "C, and the results were corrected to 25.0 "C. Chen et al (1980) found in their study of Xf virus prolonged pulsing on the application of high electric fields irreversibly changes the birefringence signal. Therefore repeated measurements on a sample were examined for systematic trends in the relaxation time and degradation artifacts that might appear in the birefringence growth curve.…”

“…and have been previously used to solve for both L and d of the filamentous viruses fd (Newman et al, 1977) and Xf (Chen et al, 1980) from measurements of 4 and 4. Figure 1 shows the appropriate plot of the Broersma equations in the current study.…”

“…The structural differ-tideslprotein subunit. Sedimentation coefficient and density increment values of Xf virus when combined with a value for the Xf translational diffusion coefficient [Chen, F. C., Koopmans, G., Wiseman, R. L., Day, L. A,, & Swinney, H. L. (1980) Biochemistry 19, 13731 yield a molecular weight of (17.9 f 1.0) X lo6 g mol-', a number of protein subunits of 3590 f 230, 2.07 f 0.15 nucleotides/protein subunit, and a mass per length of 18 300 f 1200 g mol-' nm-I. Thus, despite major differences in the DNA-protein packing between these viruses, as well as fd virus, the mass per lengths are surprisingly similar.…”