5D96: Oxidoreductase Fragment of Mouse QSOX1 in Complex with a FAb Fragment from an Antibody Targeting Mouse and Human QSOX1

The secreted disulfide catalyst Quiescin sulfhydryl oxidase-1 (QSOX1) affects extracellular matrix organization and is overexpressed in various adenocarcinomas and associated stroma. Inhibition of extracellular human QSOX1 by a monoclonal antibody decreased tumor cell migration in a cell co-culture model and hence may have therapeutic potential. However, the species specificity of the QSOX1 monoclonal antibody has been a setback in assessing its utility as an anti-metastatic agent in vivo, a common problem in the antibody therapy industry. We therefore used structurally guided engineering to expand the antibody species specificity, improving its affinity toward mouse QSOX1 by at least four orders of magnitude. A crystal structure of the re-engineered variant, complexed with its mouse antigen, revealed that the antibody accomplishes dual-species targeting through altered contacts between its heavy and light chains, plus replacement of bulky aromatics by flexible side chains and versatile water-bridged polar interactions. In parallel, we produced a surrogate antibody targeting mouse QSOX1 that exhibits a new QSOX1 inhibition mode. This set of three QSOX1 inhibitory antibodies is compatible with various mouse models for pre-clinical trials and biotechnological applications. In this study we provide insights into structural blocks to cross-reactivity and set up guideposts for successful antibody design and re-engineering.
PDB ID: 5D96Download
MMDB ID: 136395
PDB Deposition Date: 2015/8/18
Updated in MMDB: 2016/12
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Similar Structures:
Biological Unit for 5D96: trimeric; determined by software (PISA)
Molecular Components in 5D96
Label Count Molecule
Proteins (3 molecules)
Sulfhydryl Oxidase 1(Gene symbol: Qsox1)
Molecule annotation
Light Chain of FAB Fragment From an Antibody Targeting Mouse and Human Qsox1
Molecule annotation
Heavy Chain of FAB Fragment From an Antibody Targeting Mouse and Human Qsox1
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB