Keyhole limpet hemocyanin (KLH): 9A cryoEM structure and molecular model of the KLH1 didecamer reveal the interfaces and intricate topology of the 160 functional units
ELECTRON MICROSCOPY
Sample
KEYHOLE LIMPET HEMOCYANIN ISOFORM 1 (KLH1)
Specimen Preparation
Sample Aggregation State
PARTICLE
Vitrification Instrument
HOMEMADE PLUNGER
Cryogen Name
ETHANE
Sample Vitrification Details
VITRIFICATION INSTRUMENT - HOME MADE. VITRIFICATION CARRIED OUT IN 25 PERCENT OXYGEN ATMOSPHERE. SINGLE- SIDED BLOTTING
3D Reconstruction
Reconstruction Method
SINGLE PARTICLE
Number of Particles
4762
Reported Resolution (Å)
9
Resolution Method
Other Details
KLH1 IS A CYLINDRICAL 8 MDA PROTEIN WITH D5 SYMMETRY AND COMPOSED OF 20 IDENTICAL 400 KDA POLYPEPTIDE SUBUNITS. THE ASYMMETRIC UNIT IS A SUBUNIT DIMER ...
KLH1 IS A CYLINDRICAL 8 MDA PROTEIN WITH D5 SYMMETRY AND COMPOSED OF 20 IDENTICAL 400 KDA POLYPEPTIDE SUBUNITS. THE ASYMMETRIC UNIT IS A SUBUNIT DIMER (800 KDA). THE TWO CONSTITUENT POLYPEPTIDES ARE REPRESENTED HERE BY FOUR CHAINS (A, B, C, D). THIS ALLOWS A QUICK VISUALIZATION OF TWO ALTERNATIVE SUBUNIT PATHWAYS THAT HAVE BEEN PROPOSED: A-B + C-D (THIS STUDY) AND A-D + C-B (PDB-ID 3J32). THE 400 KDA POLYPEPTIDE IS FOLDED INTO EIGHT FUNCTIONAL UNITS, TERMED KLH1-A TO KLH1-H (1-421, 422-835, 836-1255, 1256-1664, 1665-2081, 2082-2488, 2489-2905, 2906-3398). THEY ARE CONCATENATED VIA LONG LINKERS. FOR THIS MODEL, THE STRUCTURE OF KLH1-H WAS AVAILABLE (PDB-ID 3QJO). HOMOLOGY MODELING OF THE OTHER FUNCTIONAL UNITS WAS DONE USING PDB-ID 1JS8 AS TEMPLATE. EACH FUNCTIONAL UNIT IS ABLE TO BIND A DIOXYGEN MOLECULE BETWEEN TWO COPPER IONS COORDINATED BY SIX HISTIDINES: 42, 60, 69, 179, 183, 210; 462, 482, 491, 602, 606, 633; 876, 896, 905, 1015, 1019, 1046; 1293, 1311, 1320, 1424, 1428, 1455; 1705, 1725, 1734, 1847, 1851, 1878; 2122, 2141, 2150, 2260, 2264, 2291; 2542, 2561, 2570, 2670, 2674, 2701; 2946, 2965, 2974, 3075, 3079, 3106. SUBMISSION BASED ON EXPERIMENTAL DATA FROM EMDB EMD-1569. (DEPOSITION ID: 6428).
