6UUI

Crystal structure of the heterocomplex between coil 2B domains of wild-type keratin 1 (KRT1) and keratin 10 (KRT10) containing mutation Cys401Ala

Summary for 6UUI

• Entry DOI: 10.2210/pdb6uui/pdb
• Related: 4ZRY
• Descriptor: Keratin, type II cytoskeletal 1, Keratin, type I cytoskeletal 10, octyl beta-D-glucopyranoside, ... (5 entities in total)
• Functional Keywords: intermediate filament, cytoskeleton, skin, coiled-coil, protein fibril
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 2
• Total formula weight: 28337.38

Authors

Lomakin, I.B.,Bunick, C.G. (deposition date: 2019-10-30, release date: 2019-11-13, Last modification date: 2023-10-11)

Primary citation

Lomakin, I.B.,Hinbest, A.J.,Ho, M.,Eldirany, S.A.,Bunick, C.G.
Crystal Structure of Keratin 1/10(C401A) 2B Heterodimer Demonstrates a Proclivity for the C-Terminus of Helix 2B to Form Higher Order Molecular Contacts.
Yale J Biol Med, 93:3-17, 2020

PubMed Abstract: We previously determined the crystal structure of the wild-type keratin 1/10 helix 2B heterodimer at 3.3 Å resolution. We proposed that the resolution of the diffraction data was limited due to the crystal packing effect from keratin 10 (K10) residue Cys401. Cys401 formed a disulfide-linkage with Cys401 from another K1/10 heterodimer, creating an "X-shaped" structure and a loose crystal packing arrangement. We hypothesized that mutation of Cys401 to alanine would eliminate the disulfide-linkage and improve crystal packing thereby increasing resolution of diffraction and enabling a more accurate side chain electron density map. Indeed, when a K10 Cys401Ala 2B mutant was paired with its native keratin 1 (K1) 2B heterodimer partner its x-ray crystal structure was determined at 2.07 Å resolution; the structure does not contain a disulfide linkage. Superposition of the K1/K10(Cys401Ala) 2B structure onto the wild-type K1/10 2B heterodimer structure had a root-mean-square-deviation of 1.88 Å; the variability in the atomic positions reflects the dynamic motion expected in this filamentous coiled-coil complex. The electrostatic, hydrophobic, and contour features of the molecular surface are similar to the lower resolution wild-type structure. We postulated that elimination of the disulfide linkage in the K1/K10(Cys401Ala) 2B structure could allow for the 2B heterodimers to bind/pack in the A tetramer configuration associated with mature keratin intermediate filament assembly. Analysis of the crystal packing revealed a half-staggered anti-parallel tetrameric complex of 2B heterodimers; however, their register is not consistent with models of the A mode of tetrameric alignment or prior biochemical cross-linking studies.

PubMed: 32226330

Experimental method

X-RAY DIFFRACTION (2.069 Å)