EC Number   |
Subunits |
Reference |
|---|
   3.6.4.B8 | heptamer |
determination and analysis of the solution structure of the complete seven subunit clamp loader complex using small angle X-ray scattering, modeling, detailed overview. The Escherichia coli core clamp loader contains the five core (delta', delta, and three truncated gamma or tau) subunits, and additionally the psi and chi subunits. The delta subunit is responsible for clamp binding and opening. The d' subunit acts as a stator and stabilizes the interaction of d subunit with the sliding clamp. The tau and gamma subunits are the active ATPases, and both gamma and tau are products of the dnaX gene. The tau and gamma clamp loading function is interchangeable and the major difference is in the length of the two proteins: gamma is a shorter version of s subunits that is created by a translational frame shift. Each DnaX subunit (either tau or gamma) binds one molecule of ATP, and the clamp loader binds and hydrolyses three ATP molecules for each loading cycle. The Escherichia coli clamp loader complex contains two other subunits psi and chi. These two subunits form a tight 1:1 elongated heterodimeric complex. The psi subunit interacts with the C-terminal region of gamma subunit. These two subunits are essential for bridging the interaction between the clamp loader and single strand DNA binding protein (SSB) in Escherichia coli. The psi subunit plays a role in stabilizing the conformational changes induced by ATP binding, the chi subunit directly interacts with the C-terminus of SSB (8 amino acid residues), and the interaction of SSB with chi subunit is increased thousand of folds when SSB is bound to DNA. The chipsi complex also plays a role in increasing the affinity of tau and gamma for delta/delta' to a physiologically relevant range |
758480 |
| 3.6.4.B8 | heptamer |
the Escherichia coli clamp loader complex CLC comprises seven subunits: delta, tau_n, gamma(3-n), delta', psi, and chi. The delta and delta' subunits (encoded by holA and holB) together with three copies of gamma and/or tau (encoded by dnaX) form a heteropentamer. The chi and psi subunits (encoded by holC and holD) are not required for clamp-loading activity, but serve to bridge the CLC with single-stranded DNA (ssDNA)-binding protein (SSB). The gamma subunit is a truncated (residues 1-431) form of tau (residues 1-643) resulting from a programmed frameshift during translation of dnaX mRNA. Enzyme pentameric and heptameric complex structures with bound DNA or SSB and without, overview. The pentameric deltagamma3delta' complex in the apo, ADP-, or ATP-gammaS-bound states are nearly identical |
758302 |
| 3.6.4.B8 | heteropentamer |
- |
-, 727783 |
| 3.6.4.B8 | heteropentamer |
4 * 37773 + 1 * 46787, calculated from sequence |
-, 725694 |
| 3.6.4.B8 | heteropentamer |
4 * 38000 + 1 * 46000, the homo-tetramer of the small subunit is complexed with one large subunit, SDS-PAGE |
-, 725694 |
| 3.6.4.B8 | hexamer |
the enzyme complex is organized as a double-layered shallow corkscrew, with the AAA+ and AAA+-like domains forming one layer, and the winged-helix domains (WHDs) forming a top layer. CDC6 fits easily between ORC1 and ORC2, completing the ring and the DNA-binding channel, forming an additional ATP hydrolysis site. The overall architecture of the HsORC motor module resembles a cashew nut. Each ORC subunit is comprised of three domains: the RecA-fold, the alpha-helical lid and the alpha-helical winged-helix domain (WHD), although the WHD domain is truncated in ORC5. The RecA-fold domain and the lid together constitute the well-known AAA+ domain. The three RecA domains form a semicircle with ATP nucleotides wedged between them in a classic AAA+ oligomerization arrangement. In the context of the motor module, only the ORC1/4 interface is a functional ATPase. SUbunit HsCDC6 binds to the core of HsORC as a second step in the assembly of the pre-RC. It is also an AAA+ ATPase with 29% sequence identity to ORC1, and completes the ring structure |
756573 |
| 3.6.4.B8 | More |
clamp loader complex organization of tau domains, the truncated version gamma comprises domains I-III, overview |
758302 |
| 3.6.4.B8 | More |
NMR resonance assignments for the N-terminal domain of the delta subunit of the gamma clamp loader complex. Nearly complete backbone and side-chain 1H, 13C and 15N NMR resonance assignments of mini-delta will facilitate NMR studies of the mechanisms of beta-clamp opening and its loading on DNA by the clamp loader |
756151 |
| 3.6.4.B8 | oligomer |
communication between subunits in the RFC holoenzyme is investigated. The small subunit alone forms a hexameric ring that is six-fold symmetric in the absence of ATP. This symmetry is broken when the nucleotide is bound to the complex. The large conformational change observed may relate to the opening of PCNA rings that is required for them to be loaded onto DNA substrates |
724844 |
| 3.6.4.B8 | oligomer |
Methanosarcina acetivorans clamp loader comprises two different small subunits (RFCS1 and RFCS2) and a large subunit (RFCL). RFCS1, RFCS2, and RFCL form a stable complex with a stoichiometric ratio of 3:1:1 |
-, 725243 |
