# Towards Understanding the Function of Aegerolysins
## 4 Aegerolysin Binary Partner Proteins  
Binary and quaternary cytolytic complexes of bacterial origin in which aegerolyins-like proteins are combined with larger, non-aegerolysin-like protein partner(s), described to date, include: **Cry16 Aa/Cry17 Aa/Cbm17.1/Cbm17.2** from _C. bifermentas subsp. malaysia_[40]; **Cry34 Ab1/Cry35 Ab1** from _B. thuringiensis_[130;134]; and **AfIP  
**1A/ AfIP-1B** from _A. faecalis_[143]. In fungus _P. ostreatus_, **PlyA** forms a pore embedded in the membrane together with **PlyB** (Figure 1) [60]. Similar cytolytic effects were observed when **PlyB** was combined with other _Pleurotus_-derived aegerolysins, e.g., **OlyA6**, **PlyA2** and **EryA**[78]. These heteromeric aegerolysin-based cytolytic complexes have been exploited as potent biopesticles for specific pests, with **Cry16 Aa**/**Cry17A**/**Cbm17.1**/**Cbm17.2** acting against _Aedes_ mosquitoes, and **Cry34 Ab1**/**Cry35 Ab1**, **AfIP-1A**/**AfIP-1B**, **OlyA6**/**PlyB**, **PlyA/**PlyB**, **PlyA2**/**PlyB**, or **EryA**/**PlyB** acting against _Coleoptera_ species, especially the western corn rootworm. Unexpectedly, partner proteins can be classified into five groups (Table 2, Figure 2): (1) **PlyB** and **EryB** have a similar MACPF fold; (2) the remaining models, including **BlyB**, showed a reasonably good superposition; **BlyB** has been shown to best align the structure of bacterial GNIP1 Aa, another MACPF domain-containing protein [52; 121]; (3) the **Cry35 Ab1** structure and (4) the **AfIP-1B** model do not superimpose with the **PlyB** structure or with each other; for **AfIP-1B**, the MACPF domain was found to be insignificant [52]; (5) **Cry16 Aa** and **Cry17A** only superimpose with each other. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Short Name** & \begin{tabular}{c} **Aegerolysin/ Structure** \\ \end{tabular} & \begin{tabular}{c} **Membrane** \\ **Receptor** \\ \end{tabular} & **Function** & \
\begin{tabular}{c} **Partner** \\ **Protein** \\ **Short Name** \\ \end{tabular} &
\begin{tabular}{c} **Partner Protein/** \\ **Structure** \\ \end{tabular} & **Organism** & **Reference** \\ \hline \multirow{4}{*}{**PlyA**} & Pleurotolysin A & & & & & & \\  & PDB ID: 4 OEBA & SM/Chol & n.d. & **PlyB** & Membrane & _Pleurotus_ & [59; 61] \\  & & & & & embedded & _ostreatus_ & \\  & & & & & PlyA/PlyB pore & & \\ \hline \multirow{4}{*}{**OlyA**} & & & & & & & \\  & & SM/Chol & mushroom & & & & & \\  & CPE/Chol & fruiting & **PlyB** & & & & \\  & Lipid rafts & Anticancer & & & & & \\  & & & & (+PlyB) & & & \\ \hline \multirow{4}{*}{**OlyA**} & & SM/Chol & & & & & & \\  & & CPE/Chol & & & & & \\  & PDB ID: 6 MY & CAEP/POPC & Insecticidal & & & & \\  & & /Chol & & & & & \\  & & Lipid rafts & & & & & \\ \hline \multirow{2}{*}{**rOly**} & Recombinant & & & Antiproliferative & n.d. & n.d. & _Pleurotus_ & [88; 89; 90] \\  & ostreolysin & & & Pro-apoptotic & & & & \\ \hline \multirow{4}{*}{**PlyA2**} & Pe.PlyA/ & SM/Chol & & & & & & \\  & CPE/Chol & & & & & & \\  & PEurotolysin A2 & CPE & & & & & \\  & Lipid rafts & & & & & \\ \hline \multirow{4}{*}{**EryA**} & & CPE/Chol & Insecticidal & & & & \\  & & & (+PlyB) & No & & & \\  & & & & (+PlyB) & No & & \\  & & & & & & \\ \hline \multirow{4}{*}{**Aa-Pri1**} & Aegerolysin & & & & & & & \\  & Aa-Pri1 & & & & & & \\ \hline \multirow{2}{*}{**MpPRIA1**} & Putative & & & & & & \\  & aegerolysin & n.d. & & & & & \\ \hline \multirow{2}{*}{**MpPRIA2**} & Putative & & & & & & \\  & aegypti & n.d. & & & & & \\ \hline \multirow{2}{*}{**MpPRIA2**} & Putative & & & & & & \\  & aegypti & n.d. & & & & & \\ \hline \multirow{4}{*}{**GME7309**} & GME7309\_g & & & & & & & \\  & aegypti- & domain- & n.d. & n.d. & n.d. & _Lignosus_ & [105] \\ \cline{1-1}  & containing & & & & & & \\ \cline{1-1}  & protein & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: List of published aegerolysins. Proteins containing a membrane-attack complex/perforin (MACPF) domain are transmembrane pore-forming proteins important for both human immunity and pathogen