TY - JOUR
T1 - The structure of sub‐nucleosomal particles
T2 - The octameric (H3/H4)4–125‐base‐pair‐DNA complex
AU - Read, Christopher M.
AU - Crane‐Robinson, Colyn
PY - 1985/1/1
Y1 - 1985/1/1
N2 - Chicken erythrocyte chromatin was depleted of histones H1, H5, H2A and H2B. The resulting (H3/H4)‐containing chromatin was digested with micrococcal nuclease to yield monomer, dimer, trimer etc. units, irregularly spaced on the DNA, with even‐number multimers being more prominent. Sucrose density gradient centrifugation separated monomers and dimers (7.7 S and 10.5 S). Sodium dodecyl sulphate gel electrophoresis and cross‐linking indicated: (a) the monomer contains 50‐base‐pair (bp), 60‐bp and 70‐bp DNA and the dimer 125‐bp DNA; (b) the monomer contains a tetramer and the dimer an octamer of H3 and H4. Partial association of monomer units to dimers inhibits structural studies of monomers. The internal structure of the dimer, i.e. an (H3/H4)4–125‐bp‐DNA particle, was studied using circular dichroism, thermal denaturation and nuclease digestion. Both micrococcal nuclease and DNase I digestion indicate that, unlike core particles, accessible sites occur in the centre of the particle and it is concluded that the (H3/H4)4—125‐bp‐DNA particle is not a ‘pseudo‐core particle’ in which the ‘extra’ H3 and H4 replace H2A and H2B. It is proposed that the octamer particle is formed by the sliding together of two ‘monomer’ units, each containing the (H3/H4)2 tetramer and 70 bp of DNA. Excision of this dimer unit with micrococcal nuclease results in the loss of 10 readily digestible base pairs at each end, leaving 125 bp.
AB - Chicken erythrocyte chromatin was depleted of histones H1, H5, H2A and H2B. The resulting (H3/H4)‐containing chromatin was digested with micrococcal nuclease to yield monomer, dimer, trimer etc. units, irregularly spaced on the DNA, with even‐number multimers being more prominent. Sucrose density gradient centrifugation separated monomers and dimers (7.7 S and 10.5 S). Sodium dodecyl sulphate gel electrophoresis and cross‐linking indicated: (a) the monomer contains 50‐base‐pair (bp), 60‐bp and 70‐bp DNA and the dimer 125‐bp DNA; (b) the monomer contains a tetramer and the dimer an octamer of H3 and H4. Partial association of monomer units to dimers inhibits structural studies of monomers. The internal structure of the dimer, i.e. an (H3/H4)4–125‐bp‐DNA particle, was studied using circular dichroism, thermal denaturation and nuclease digestion. Both micrococcal nuclease and DNase I digestion indicate that, unlike core particles, accessible sites occur in the centre of the particle and it is concluded that the (H3/H4)4—125‐bp‐DNA particle is not a ‘pseudo‐core particle’ in which the ‘extra’ H3 and H4 replace H2A and H2B. It is proposed that the octamer particle is formed by the sliding together of two ‘monomer’ units, each containing the (H3/H4)2 tetramer and 70 bp of DNA. Excision of this dimer unit with micrococcal nuclease results in the loss of 10 readily digestible base pairs at each end, leaving 125 bp.
UR - http://www.scopus.com/inward/record.url?scp=0022185716&partnerID=8YFLogxK
U2 - 10.1111/j.1432-1033.1985.tb09174.x
DO - 10.1111/j.1432-1033.1985.tb09174.x
M3 - Article
C2 - 4043075
AN - SCOPUS:0022185716
SN - 0014-2956
VL - 152
SP - 143
EP - 150
JO - European Journal Of Biochemistry
JF - European Journal Of Biochemistry
IS - 1
ER -