TY - JOUR

T1 - Observation of nucleic acid and protein correlation in chromatin of HeLa nuclei using small-angle neutron scattering with D2O-H2O contrast variation

AU - Григорьев, Сергей Валентинович

AU - Iashina, E. G.

AU - Wu, B.

AU - Pipich, V.

AU - Lang, Ch.

AU - Radulescu, A.

AU - Bairamukov, V. Yu.

AU - V. Filatov, M.

AU - Pantina, R. A.

AU - Varfolomeeva, E. Yu.

PY - 2021/10/7

Y1 - 2021/10/7

N2 - The small-angle neutron scattering (SANS) on HeLa nuclei demonstrates the bifractal nature of the chromatin structural organization. The border line between two fractal structures is detected as a crossover point at Qc approximate to 4x10-2 nm-1 in the momentum transfer dependence Q-D. The use of contrast variation (D2O-H2O) in SANS measurements reveals clear similarity in the large scale structural organizations of nucleic acids (NA) and proteins. Both NA and protein structures have a mass fractal arrangement with the fractal dimension of D approximate to 2.5 at scales smaller than 150 nm down to 20 nm. Both NA and proteins show a logarithmic fractal behavior with D approximate to 3 at scales larger than 150 nm up to 6000 nm. The combined analysis of the SANS and atomic force microscopy data allows one to conclude that chromatin and its constitutes (DNA and proteins) are characterized as soft, densely packed, logarithmic fractals on the large scale and as rigid, loosely packed, mass fractals on the smaller scale. The comparison of the partial cross sections from NA and proteins with one from chromatin as a whole demonstrates spatial correlation of two chromatin's components in the range up to 900 nm. Thus chromatin in HeLa nuclei is built as the unified structure of the NA and proteins entwined through each other. Correlation between two components is lost upon scale increases toward 6000 nm. The structural features at the large scale, probably, provide nuclei with the flexibility and chromatin-free space to build supercorrelations on the distance of 103 nm resembling cycle cell activity, such as an appearance of nucleoli and a DNA replication.

AB - The small-angle neutron scattering (SANS) on HeLa nuclei demonstrates the bifractal nature of the chromatin structural organization. The border line between two fractal structures is detected as a crossover point at Qc approximate to 4x10-2 nm-1 in the momentum transfer dependence Q-D. The use of contrast variation (D2O-H2O) in SANS measurements reveals clear similarity in the large scale structural organizations of nucleic acids (NA) and proteins. Both NA and protein structures have a mass fractal arrangement with the fractal dimension of D approximate to 2.5 at scales smaller than 150 nm down to 20 nm. Both NA and proteins show a logarithmic fractal behavior with D approximate to 3 at scales larger than 150 nm up to 6000 nm. The combined analysis of the SANS and atomic force microscopy data allows one to conclude that chromatin and its constitutes (DNA and proteins) are characterized as soft, densely packed, logarithmic fractals on the large scale and as rigid, loosely packed, mass fractals on the smaller scale. The comparison of the partial cross sections from NA and proteins with one from chromatin as a whole demonstrates spatial correlation of two chromatin's components in the range up to 900 nm. Thus chromatin in HeLa nuclei is built as the unified structure of the NA and proteins entwined through each other. Correlation between two components is lost upon scale increases toward 6000 nm. The structural features at the large scale, probably, provide nuclei with the flexibility and chromatin-free space to build supercorrelations on the distance of 103 nm resembling cycle cell activity, such as an appearance of nucleoli and a DNA replication.

KW - FRACTAL DIMENSION

KW - ORGANIZATION

KW - CHROMOSOMES

KW - PHYSICS

KW - FIBERS

KW - ROUGH

U2 - 10.1103/physreve.104.044404

DO - 10.1103/physreve.104.044404

M3 - статья

VL - 104

JO - Physical Review E

JF - Physical Review E

SN - 1539-3755

IS - 4

M1 - 044404

ER -