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Atomic-Resolution Structures of the APC/C Subunits Apc4 and the Apc5 N-Terminal Domain.

Cronin NB, Yang J, Zhang Z, Kulkarni K, Chang L, Yamano H, Barford D - J. Mol. Biol. (2015)

Bottom Line: In a separate study, we had fitted these atomic models to a 3.6-Å-resolution cryo-electron microscopy map of the APC/C.We describe how, in the context of the APC/C, regions of Apc4 disordered in the crystal assume order through contacts to Apc5, whereas Apc5(N) shows small conformational changes relative to its crystal structure.We discuss the complementary approaches of high-resolution electron microscopy and protein crystallography to the structure determination of subunits of multimeric complexes.

View Article: PubMed Central - PubMed

Affiliation: Division of Structural Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, United Kingdom.

No MeSH data available.


Related in: MedlinePlus

Apc4 comprises a WD40 β-propeller toroid split by a helical bundle domain. (a) Cartoon of Apc4 color-ramped from blue to red from N- to C-termini. Shown is the EM structure of human Apc4. (b) Close-up view of the extended blade 5 of Apc4WD40 and showing the βD4/βA5 loop that blocks access to the mouth of the WD40 domain tunnel. (c) Stereoview showing that the M-domain of α-catenin, superimposed onto the EM structure of human Apc4HBD, shares structural similarity with the four-helical-bundle domain of Apc4.
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f0010: Apc4 comprises a WD40 β-propeller toroid split by a helical bundle domain. (a) Cartoon of Apc4 color-ramped from blue to red from N- to C-termini. Shown is the EM structure of human Apc4. (b) Close-up view of the extended blade 5 of Apc4WD40 and showing the βD4/βA5 loop that blocks access to the mouth of the WD40 domain tunnel. (c) Stereoview showing that the M-domain of α-catenin, superimposed onto the EM structure of human Apc4HBD, shares structural similarity with the four-helical-bundle domain of Apc4.

Mentions: The human Apc4 crystal structure was fitted into the 3.6-Å-resolution cryo-EM density map of APC/CCdh1.Emi1[44] using Chimera [46] (Fig. 1 and Supplementary Fig. 2c). Residues of the Apc4 helical bundle domain HBD (Apc4HBD) were well resolved in EM density, and segments of the Apc4HBD not visible in the crystal structures could be built ab initio into the EM density, allowing an almost complete atomic model to be generated and refined [44] (Supplementary Fig. 1). C-terminal residues (758–808) of human Apc4 are disordered in both the crystal structure and the EM density map. In contrast, as discussed below, the WD40 β-propeller domain, which is well resolved and ordered in the crystal structures, is less well defined in the EM density, being located at the periphery of the complex (Supplementary Fig. 2b).


Atomic-Resolution Structures of the APC/C Subunits Apc4 and the Apc5 N-Terminal Domain.

Cronin NB, Yang J, Zhang Z, Kulkarni K, Chang L, Yamano H, Barford D - J. Mol. Biol. (2015)

Apc4 comprises a WD40 β-propeller toroid split by a helical bundle domain. (a) Cartoon of Apc4 color-ramped from blue to red from N- to C-termini. Shown is the EM structure of human Apc4. (b) Close-up view of the extended blade 5 of Apc4WD40 and showing the βD4/βA5 loop that blocks access to the mouth of the WD40 domain tunnel. (c) Stereoview showing that the M-domain of α-catenin, superimposed onto the EM structure of human Apc4HBD, shares structural similarity with the four-helical-bundle domain of Apc4.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590430&req=5

f0010: Apc4 comprises a WD40 β-propeller toroid split by a helical bundle domain. (a) Cartoon of Apc4 color-ramped from blue to red from N- to C-termini. Shown is the EM structure of human Apc4. (b) Close-up view of the extended blade 5 of Apc4WD40 and showing the βD4/βA5 loop that blocks access to the mouth of the WD40 domain tunnel. (c) Stereoview showing that the M-domain of α-catenin, superimposed onto the EM structure of human Apc4HBD, shares structural similarity with the four-helical-bundle domain of Apc4.
Mentions: The human Apc4 crystal structure was fitted into the 3.6-Å-resolution cryo-EM density map of APC/CCdh1.Emi1[44] using Chimera [46] (Fig. 1 and Supplementary Fig. 2c). Residues of the Apc4 helical bundle domain HBD (Apc4HBD) were well resolved in EM density, and segments of the Apc4HBD not visible in the crystal structures could be built ab initio into the EM density, allowing an almost complete atomic model to be generated and refined [44] (Supplementary Fig. 1). C-terminal residues (758–808) of human Apc4 are disordered in both the crystal structure and the EM density map. In contrast, as discussed below, the WD40 β-propeller domain, which is well resolved and ordered in the crystal structures, is less well defined in the EM density, being located at the periphery of the complex (Supplementary Fig. 2b).

Bottom Line: In a separate study, we had fitted these atomic models to a 3.6-Å-resolution cryo-electron microscopy map of the APC/C.We describe how, in the context of the APC/C, regions of Apc4 disordered in the crystal assume order through contacts to Apc5, whereas Apc5(N) shows small conformational changes relative to its crystal structure.We discuss the complementary approaches of high-resolution electron microscopy and protein crystallography to the structure determination of subunits of multimeric complexes.

View Article: PubMed Central - PubMed

Affiliation: Division of Structural Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, United Kingdom.

No MeSH data available.


Related in: MedlinePlus