Dataset Information

Cleavage Alters the Molecular Determinants of Protein Kinase C-? Catalytic Activity.

ABSTRACT: Protein kinase C-? (PKC?) is an allosterically activated enzyme that acts much like other PKC isoforms to transduce growth factor-dependent signaling responses. However, PKC? is unique in that activation loop (Thr507) phosphorylation is not required for catalytic activity. Since PKC? can be proteolytically cleaved by caspase-3 during apoptosis, the prevailing assumption has been that the kinase domain fragment (?KD) freed from autoinhibitory constraints imposed by the regulatory domain is catalytically competent and that Thr507 phosphorylation is not required for ?KD activity. This study provides a counternarrative showing that ?KD activity is regulated through Thr507 phosphorylation. We show that Thr507-phosphorylated ?KD is catalytically active and not phosphorylated at Ser359 in its ATP-positioning G-loop. In contrast, a ?KD fragment that is not phosphorylated at Thr507 (which accumulates in doxorubicin-treated cardiomyocytes) displays decreased C-terminal tail priming-site phosphorylation, increased G-loop Ser359 phosphorylation, and defective kinase activity. ?KD is not a substrate for Src, but Src phosphorylates ?KD-T507A at Tyr334 (in the newly exposed ?KD N terminus), and this (or an S359A substitution) rescues ?KD-T507A catalytic activity. These results expose a unique role for ?KD-Thr507 phosphorylation (that does not apply to full-length PKC?) in structurally organizing diverse elements within the enzyme that critically regulate catalytic activity.

SUBMITTER: Gong J

PROVIDER: S-EPMC5615191 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Cleavage Alters the Molecular Determinants of Protein Kinase C-δ Catalytic Activity.

Gong Jianli J Park Misun M Steinberg Susan F SF

Molecular and cellular biology 20170926 20

Protein kinase C-δ (PKCδ) is an allosterically activated enzyme that acts much like other PKC isoforms to transduce growth factor-dependent signaling responses. However, PKCδ is unique in that activation loop (Thr<sup>507</sup>) phosphorylation is not required for catalytic activity. Since PKCδ can be proteolytically cleaved by caspase-3 during apoptosis, the prevailing assumption has been that the kinase domain fragment (δKD) freed from autoinhibitory constraints imposed by the regulatory domai ...[more]

PMID: 28784722

Similar Datasets

Project description:Protein kinases are key enzymes in many signal transduction pathways, and play a crucial role in cellular proliferation, differentiation, and various cell regulatory processes. However, aberrant function of kinases has been associated with cancers and many other diseases. Consequently, competitive inhibition of the ATP binding site of protein kinases has emerged as an effective means of curing these diseases. Over the past three decades, thousands of protein kinase inhibitors (PKIs) with varying molecular frames have been developed. Large-scale data mining of the Protein Data Bank resulted in a database of 2139 non-redundant high-resolution X-ray crystal structures of PKIs bound to protein kinases. This provided us with a unique opportunity to study molecular determinants for the molecular recognition of PKIs. A chemoinformatic analysis of 2139 PKIs resulted in findings that PKIs are "flat" molecules with high aromatic ring counts and low fractions of sp3 carbon. All but one PKI possessed one or more aromatic rings. More importantly, it was found that the average weighted hydrogen bond count is inversely proportional to the number of aromatic rings. Based on this linear relationship, we put forward the exchange rule of hydrogen bonding interactions and non-bonded π-interactions. Specifically, a loss of binding affinity caused by a decrease in hydrogen bonding interactions is compensated by a gain in binding affinity acquired by an increase in aromatic ring-originated non-bonded interactions (i.e., π-π stacking interactions, CH-π interactions, cation-π interactions, etc.), and vice versa. The very existence of this inverse relationship strongly suggests that both hydrogen bonding and aromatic ring-originated non-bonded interactions are responsible for the molecular recognition of PKIs. As an illustration, two representative PKI-kinase complexes were employed to examine the relative importance of different modes of non-bonded interactions for the molecular recognition of PKIs. For this purpose, two FDA-approved PKI drugs, ibrutinib and lenvatinib, were chosen. The binding pockets of both PKIs were thoroughly examined to identify all non-bonded intermolecular interactions. Subsequently, the strengths of interaction energies between ibrutinib and its interacting residues in tyrosine kinase BTK were quantified by means of the double hybrid DFT method B2PLYP. The resulting energetics for the binding of ibrutinib in tyrosine kinase BTK showed that CH-π interactions and π-π stacking interactions between aromatic rings of the drug and hydrophobic residues in its binding pocket dominate the binding interactions. Thus, this work establishes that, in addition to hydrogen bonding, aromatic rings function as important molecular determinants for the molecular recognition of PKIs. In conclusion, our findings support the following pharmacophore model for ATP-competitive kinase inhibitors: a small molecule features a scaffold of one or more aromatic rings which is linked with one or more hydrophilic functional groups. The former has the structural role of acting as a scaffold and the functional role of participating in aromatic ring-originated non-bonded interactions with multiple hydrophobic regions in the ATP binding pocket of kinases. The latter ensure water solubility and form hydrogen bonds with the hinge region and other hydrophilic residues of the ATP binding pocket.

Dataset Information

Cleavage Alters the Molecular Determinants of Protein Kinase C-? Catalytic Activity.

Publications

Cleavage Alters the Molecular Determinants of Protein Kinase C-δ Catalytic Activity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets