9CFS
Structure of a 150% lengthened variant of the E. coli ROP protein
Summary for 9CFS
| Entry DOI | 10.2210/pdb9cfs/pdb |
| Related | 7kae |
| Descriptor | Long regulatory protein rop, NICKEL (II) ION (3 entities in total) |
| Functional Keywords | 4-helix bundle, engineered, extended, rom, rna binding protein |
| Biological source | Escherichia coli |
| Total number of polymer chains | 2 |
| Total formula weight | 21659.38 |
| Authors | Gallagher, D.T.,Shakya, A. (deposition date: 2024-06-27, release date: 2025-07-02, Last modification date: 2026-07-15) |
| Primary citation | Karageorgos, I.,Gallagher, D.T. Heptad insertion extends the E. coli ROP protein by 50. Biodes Res, 8:100061-100061, 2026 Cited by PubMed Abstract: Antibody function involves conformational variability, yet their extreme flexibility complicates measurement of their structure and properties. They also have numerous ligands, suggesting that a rigid bivalent ligand construct of appropriate length could interact with an antibody to reduce its flexibility for imaging, measurement or functional effect. Such a construct would ideally have an inter-ligand spacer that is fairly rigid and with length between 6 and 10 nm. Coiled-coil bundles of alpha helices represent a common motif in protein structure whose relatively simple parallel geometry makes them suitable for rational modification including applications in metrology. In this study, we describe a heptad-insertion heuristic for extending bundles and apply it to the ROP/ROM protein, which is a 13 kDa, thermostable RNA-binding unit that is naturally a 4-helix dimer and has been engineered to self-associate in various ways to form larger assemblies. We first introduced a tryptophan residue into the core (wild-type lacks tryptophan) to support precise quantitation, and then extended the protein to 150 % of its native length by inserting four helical heptads. We report the engineering process and crystal structures of the tryptophan mutant and the lengthened protein, which also contains a new phenylalanine in the core. Where wild-type has a length of 4.3 nm, the extended variant has length 6.5 nm and may serve as a rigid module for higher order constructs. PubMed: 42038005DOI: 10.1016/j.bidere.2025.100061 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.75 Å) |
Structure validation
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