Insights in small Heat Shock Protein/client interaction by combined protection analysis of two different client proteins

sHSPs interact with clients under denaturing conditions. CPH1Δ2, a truncated version of cyanobacterial phytochrome CPH1, was introduced as a new reporter (client). Comparative analyses of At17.8 and At17.6B as cytosolic class I sHSP representatives demonstrated the advantages of a chromophore-bearing photoreversible protein as new client for analyzing sHSP holdase function in addition to malate dehydrogenase (MDH). The tested sHSPs protected both clients in similar ways but with different efficiencies. Bis-ANS binding studies with sHSPs suggested that the bis-ANS binding is dependent on interactions between different sHSPs and MDH under denaturing temperatures.Structured summary of protein interactionsCPH1Δ2 and CPH1Δ2bind by molecular sieving (View interaction)CPH1Δ2 and HSP17.8bind by molecular sieving (View interaction)CPH1Δ2 and HSP17.6bind by molecular sieving (View interaction)MDH and HSP17.8bind by molecular sieving (View interaction)MDH and HSP17.6Bbind by molecular sieving (View interaction)

► Comparative analysis of MDH and CPH1Δ2 as clients in sHSP protection analysis.
► At17.6B-CI and At17.8-CI were tested.
► sHSPs kept both clients soluble but inactive under denaturing conditions.
► Chosen sHSPs showed different protection efficiencies.
► sHSPs competed with bis-ANS for MDH interaction under denaturing conditions.