biostudies-literaturePan SNSFCNKBRSF14871https://www.ebi.ac.uk/biostudies/studies/S-EPMC7483523biostudies-literatureUnknown10(1)Outer membrane proteins (OMPs) are essential to gram-negative bacteria, and molecular chaperones prevent the OMPs from aggregation in the periplasm during the OMPs biogenesis. Skp is one of the molecular chaperones for this purpose. Here, we combined single-molecule fluorescence resonance energy transfer and fluorescence correlation spectroscopy to study the affinity and stoichiometric ratio of Skp in its binding with OmpC at the single-molecule level. The half concentration of the Skp self-trimerization (C_1/2) was measured to be (2.5 ± 0.7) × 10² nM. Under an Skp concentration far below the C_1/2, OmpC could recruit Skp monomers to form OmpC·Skp₃. The affinity to form the OmpC·Skp₃ complex was determined to be (5.5 ± 0.4) × 10<sup>2</sScientific reportsAffinity of Skp to OmpC revealed by single-molecule detection.PMC7483523215210032012CB917304Pan SYang CZhao XSfalseAffinity of Skp to OmpC revealed by single-molecule detection.Outer membrane proteins (OMPs) are essential to gram-negative bacteria, and molecular chaperones prevent the OMPs from aggregation in the periplasm during the OMPs biogenesis. Skp is one of the molecular chaperones for this purpose. Here, we combined single-molecule fluorescence resonance energy transfer and fluorescence correlation spectroscopy to study the affinity and stoichiometric ratio of Skp in its binding with OmpC at the single-molecule level. The half concentration of the Skp self-trimerization (C_1/2) was measured to be (2.5 ± 0.7) × 10² nM. Under an Skp concentration far below the C_1/2, OmpC could recruit Skp monomers to form OmpC·Skp₃. The affinity to form the OmpC·Skp₃ complex was determined to be (5.5 ± 0.4) × 10<sup>2</s2020-01-01T00:00:00Z2020 Sep2026-04-17T11:05:10.36Z2020-09-18T07:06:41ZS-EPMC74835233291324310.1038/s41598-020-71608-4