Related Experiment Video
Updated: Feb 1, 2026

Kinase Inhibitor Screening In Self-assembled Human Protein Microarrays
Published on: October 23, 2019
Identification of human plasma C1 inhibitor as a target protein for staphylococcal superantigen-like protein 5 (SSL5)
Teruaki Oku1, Chisato Kurisaka1, Yusuke Ando1
1Department of Microbiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo, Japan.
Abstract:
The family of staphylococcal superantigen-like proteins (SSLs) have a structure similar to bacterial superantigens but exhibit no superantigenic activity. These exoproteins have recently been shown to disturb the host immune defense system. One family member, SSL5, was reported to bind to human leukocyte P-selectin glycoprotein ligand-1 (PSGL-1) and matrix metalloproteinase-9 (MMP-9) and to interfere with leukocyte trafficking. In the present study, we explored human plasma proteins bound by glutathione S-transferase (GST)-tagged recombinant SSL5 (GST-SSL5) and identified plasma protease C1 inhibitor (C1Inh) as a major SSL5-binding protein based on the results of peptide mass fingerprinting analysis with MALDI-TOFMS. GST-SSL5 was found to attenuate the inhibitory activity of recombinant histidine-tagged C1Inh (C1Inh-His) toward complement C1s. We also observed that the treatment of C1Inh-His with neuraminidase markedly decreased its binding to GST-SSL5. Moreover, C1Inh-His produced by Lec2 mutant cells (deficient in sialic acid biosynthesis) showed much lower binding affinity for SSL5 than that produced by the wild-type CHO-K1 cells, as assessed by pull-down assay. These results suggest that SSL5 binds to C1Inh in a sialic acid-dependent fashion and modulates the host immune defense through perturbation of the complement system in association with S. aureus infection.
More Related Videos
07:02TurboID-Based Proximity Labeling for In Planta Identification of Protein-Protein Interaction Networks
Published on: May 17, 2020
10:33Development of Inhibitors of Protein-protein Interactions through REPLACE: Application to the Design and Development Non-ATP Competitive CDK Inhibitors
Published on: October 26, 2015
Related Concept Videos
Drug Distribution: Plasma Protein Binding
Protein Buffers in Blood Plasma and Cells
Certain amino acids can exist in a zwitterion state at a...
Conservation of Protein Domains Over Different Proteins
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to...
Protein-protein Interfaces
Protein and Protein Structure
A protein's shape is critical to its function. For example, an enzyme...
Introduction to Membrane Proteins