Structural insights into the interactions of phorbol ester and bryostatin complexed with protein kinase C: a comparative molecular dynamics simulation study
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Updated: Apr 5, 2026
Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein
Published on: June 30, 2019
Patcharapong Thangsunan1,2, Suriya Tateing1,2, Supa Hannongbua3
1a Graduate Program in Biotechnology , The Graduate School, Chiang Mai University , 239 Huay Kaew Rd, Suthep, Muang, Chiang Mai 50200 , Thailand.
Abstract:
Protein kinase C (PKC) isozymes are important regulatory enzymes that have been implicated in many diseases, including cancer, Alzheimer's disease, and in the eradication of HIV/AIDS. Given their potential clinical ramifications, PKC modulators, e.g. phorbol esters and bryostatin, are also of great interest in the drug development. However, structural details on the binding between PKC and its modulators, especially bryostatin - the highly potent and non-tumor promoting activator for PKCs, are still lacking. Here, we report the first comparative molecular dynamics study aimed at gaining structural insight into the mechanisms by which the PKC delta cys2 activator domain is used in its binding to phorbol ester and bryostatin-1. As anticipated in the phorbol ester binding, hydrogen bonds are formed through the backbone atoms of Thr242, Leu251, and Gly253 of PKC. However, the opposition of H-bond formation between Thr242 and Gly253 may cause the phorbol ester complex to become less stable when compared with the bryostatin binding. For the PKC delta-bryostatin complex, hydrogen bonds are formed between the Gly253 backbone carbonyl and the C30 carbomethoxy substituent of the ligand. Additionally, the indole Nε1 of the highly homologous Trp252 also forms an H-bond to the C20 ester group on bryostatin. Backbone fluctuations also suggest that this latter H-bond formation may abrogate the transient interaction between Trp252 and His269, thus dampening the fluctuations observed on the nearby Zn(2+)-coordinating residues. This new dynamic fluctuation dampening model can potentially benefit future design of new PKC modulators.
Insights
Structural insights reveal how bryostatin binds Protein Kinase C (PKC) delta more stably than phorbol esters. This dynamic dampening model aids in designing novel PKC modulators for diseases like cancer and HIV/AIDS.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Protein Kinase C (PKC) isozymes regulate crucial cellular processes and are implicated in diseases such as cancer and HIV/AIDS.
- PKC modulators, including phorbol esters and bryostatin, are vital in drug development, yet structural binding details are limited.
- Bryostatin is a potent, non-tumorigenic PKC activator, making its binding mechanism particularly important.
Purpose of the Study:
- To provide the first comparative molecular dynamics study of PKC delta activator domain binding to phorbol ester and bryostatin-1.
- To elucidate the structural mechanisms underlying the differential binding stability of these PKC modulators.
- To offer insights for the future design of novel PKC-targeting therapeutics.
Main Methods:
- Comparative molecular dynamics simulations were performed on the PKC delta cys2 activator domain.
- Analysis focused on hydrogen bond formation and backbone fluctuations during ligand binding.
- Key residues involved in ligand interaction and their impact on complex stability were identified.
Main Results:
- Phorbol ester binding involves hydrogen bonds with Thr242, Leu251, and Gly253, but potential instability due to Thr242-Gly253 opposition.
- Bryostatin-1 binding forms hydrogen bonds between Gly253 and its C30 substituent, and Trp252 with bryostatin's C20 ester.
- Bryostatin binding dampens backbone fluctuations near Zn(2+)-coordinating residues, suggesting a more stable complex.
Conclusions:
- The study reveals distinct hydrogen bonding patterns and dynamic behaviors for phorbol ester and bryostatin-1 binding to PKC delta.
- Bryostatin-1's interaction leads to a more stable complex through a dynamic fluctuation dampening mechanism.
- These findings provide a structural basis for designing improved PKC modulators with enhanced therapeutic potential.
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