1EM8: Chi and psi subunit heterodimer from DNA POL III

Crystal structure of chi and psi subunit heterodimer from DNA POL III. Determined by X-ray diffraction at 2.1 Å resolution. Released 26 Aug 2003.

Method: X-ray diffraction
Resolution: 2.1 Å
Organism: Escherichia coli
Chains: 4
Atoms: 4,225
Mol. weight: 57.72 kDa
Released: 26 Aug 2003

Explore 1EM8 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

1EM8 contains 28 α-helices and 30 β-strands across 4 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 6 helices, 9 β-strands

Element	Residues	Length	Sheet
β-strand	2-8	7	1
α-helix	9	1
β-strand	15	1	2
β-strand	18	1	2
α-helix	20-34	15
β-strand	39-42	4	1
α-helix	46-58	13
β-strand	67-69	3	1
β-strand	80-83	4	1
α-helix	88-90	3
β-strand	95-98	4	1
α-helix	105-109	5
β-strand	112-117	6	1
α-helix	121-136	16
β-strand	139-144	6	1

Chain B: 9 helices, 6 β-strands

Element	Residues	Length	Sheet
α-helix	31-34	4
β-strand	39-42	4	3
α-helix	52-60	9
α-helix	65-67	3
β-strand	68-71	4	3
α-helix	75-78	4
α-helix	80	1
β-strand	84	1	4
β-strand	86-90	5	3
α-helix	95-96	2
β-strand	99	1	4
β-strand	102-105	4	3
α-helix	108-113	6
α-helix	115-127	13
α-helix	129-132	4

Chain C: 6 helices, 9 β-strands

Element	Residues	Length	Sheet
β-strand	3-8	6	5
α-helix	9	1
β-strand	15	1	6
β-strand	18	1	6
α-helix	20-34	15
β-strand	39-42	4	5
α-helix	46-55	10
β-strand	67-69	3	5
β-strand	80-83	4	5
β-strand	95-98	4	5
α-helix	105-109	5
β-strand	112-117	6	5
α-helix	121-136	16
α-helix	139	1
β-strand	140-144	5	5

Chain D: 7 helices, 6 β-strands

Element	Residues	Length	Sheet
α-helix	32-34	3
β-strand	39-42	4	7
α-helix	52-60	9
α-helix	65-67	3
β-strand	68-71	4	7
α-helix	73-78	6
β-strand	84	1	8
β-strand	87-90	4	7
β-strand	99	1	8
β-strand	102-105	4	7
α-helix	108-113	6
α-helix	115-127	13
α-helix	129-132	4

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
DNA polymerase III chi subunit	A, C	protein	147	Escherichia coli	P28905 (AlphaFold model)
DNA polymerase III psi subunit	B, D	protein	112	Escherichia coli	P28632 (AlphaFold model)

Sequence of entity 1 (A, C), FASTA

>1EM8_1 DNA POLYMERASE III CHI SUBUNIT (chains A, C)
MKNATFYLLDNDTTVDGLSAVEQLVCEIAAERWRSGKRVLIACEDEKQAYRLDEALWARP
AESFVPHNLAGEGPRGGAPVEIAWPQKRSSSRRDILISLRTSFADFATAFTEVVDFVPYE
DSLKQLARERYKAYRVAGFNLNTATWK

Sequence of entity 2 (B, D), FASTA

>1EM8_2 DNA POLYMERASE III PSI SUBUNIT (chains B, D)
QGEIAIAIPAHVRLVMVANDLPALTDPLVSDVLRALTVSPDQVLQLTPEKIAMLPQGSHC
NSWRLGTDEPLSLEGAQVASPALTDLRANPTARAALWQQICTYEHDFFPRND

Primary citation

Crystal structure of the chi:psi sub-assembly of the Escherichia coli DNA polymerase clamp-loader complex. Gulbis, J.M., Kazmirski, S.L., Finkelstein, J. et al. Eur J Biochem (2004) 271:439-449. DOI 10.1046/j.1432-1033.2003.03944.x · PubMed

Other PDB entries of the same protein (UniProt P28905 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3SXU 1.85 Å, Structure of the E. coli SSB-DNA polymerase III interface
9OYH 2.54 Å, Structure of the E. coli clamp loader DnaX-complex loading beta-clamp onto 10-nt gapped…

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