Figure 1

Architecture of staphylococcal HtrA proteins and design of soluble proteins. Three HtrA family members are shown: from top to bottom, E. coli DegS, S. aureus HtrA₁ and HtrA₂ proteins (strain COL). They display the typical domain organisation of the family: transmembrane, catalytic and PDZ domains are shown as hatched, dark grey and light grey boxes respectively, with their boundaries (residue position) indicated below. The catalytic Serine residue (S, in bold) is shown. The recombinant DegS form whose structure has been solved after N-terminal transmembrane domain deletion [64] is named DegSΔTM. A similar deletion strategy was applied to HtrA₁ and HtrA₂ proteins leading to N-terminally truncated proteins named HtrA₁ΔTM and HtrA₂ΔTM. All truncated protein forms are shown as lines with the position of their first and last residues in the corresponding WT sequence indicated.