8IWA

Crystal structure of Q9PR55 at pH 6.5

Summary for 8IWA

• Entry DOI: 10.2210/pdb8iwa/pdb
• Descriptor: Uncharacterized protein UU089.1, SULFATE ION (3 entities in total)
• Functional Keywords: knotted protein, structural protein
• Biological source: Ureaplasma parvum serovar 3 str. ATCC 700970
• Total number of polymer chains: 8
• Total formula weight: 84216.90

Authors

Hsu, M.F.,Ko, T.P.,Huang, K.F.,Chen, Y.R.,Huang, J.S.,Hsu, S.T.D. (deposition date: 2023-03-29, release date: 2024-02-07)

Primary citation

Hsu, M.F.,Sriramoju, M.K.,Lai, C.H.,Chen, Y.R.,Huang, J.S.,Ko, T.P.,Huang, K.F.,Hsu, S.D.
Structure, dynamics, and stability of the smallest and most complex 7 1 protein knot.
J.Biol.Chem., 300:105553-105553, 2023

PubMed Abstract: Proteins can spontaneously tie a variety of intricate topological knots through twisting and threading of the polypeptide chains. Recently developed artificial intelligence algorithms have predicted several new classes of topological knotted proteins, but the predictions remain to be authenticated experimentally. Here, we showed by X-ray crystallography and solution-state NMR spectroscopy that Q9PR55, an 89-residue protein from Ureaplasma urealyticum, possesses a novel 7 knotted topology that is accurately predicted by AlphaFold 2, except for the flexible N terminus. Q9PR55 is monomeric in solution, making it the smallest and most complex knotted protein known to date. In addition to its exceptional chemical stability against urea-induced unfolding, Q9PR55 is remarkably robust to resist the mechanical unfolding-coupled proteolysis by a bacterial proteasome, ClpXP. Our results suggest that the mechanical resistance against pulling-induced unfolding is determined by the complexity of the knotted topology rather than the size of the molecule.

PubMed: 38072060
DOI: 10.1016/j.jbc.2023.105553

Experimental method

X-RAY DIFFRACTION (2.51 Å)