Cloning and characterisation of PKB and PRK homologs from Hydra and the evolution of the protein kinase family

Abstract

Two new serine/threonine protein kinases have been cloned from Hydra cDNA. The first of these kinases belongs to the PKB/Akt family. It is expressed ubiquitously in Hydra at a relatively low level but is upregulated during head regeneration. The second kinase is a member of the PRK/PKN family. It is ubiquitously expressed in Hydra tissue, albeit at a higher level than PKB. Construction of a phylogenetic tree including the Hydra PRK and PKB kinases and two PKC homologs previously cloned by Hassel and comparing them with members of the PKC, PKB and PRK families from porifera, Dictyostelium,yeast, Drosophila, Caenorhabditis and humans provide support for a simple model for the evolution of these kinase families. An ancestral precursor which contained a pleckstrin homology domain in its N-terminus and a C-terminal kinase domain gave rise to PKB in Dictyostelium. From this ancestor the PKB/PRK and PKC families evolved. The pleckstrin homology domain was lost in the PKC and PRK families and kept in the PKB family. PKB homologs have now been found in a variety of multicellular animals with Hydra being the phylogenetically earliest representative. Members of the PRK/PKC family, on the other hand, are also present in fungi. The precursor for these kinases must have contained N-terminal regulatory domains that were retained in fungal PRKs but subsequently partitioned between kinases of the PKC and PRK groups in metazoans.

Molecular Cloning and Expression of Starfish Protein Kinase C Isoforms

“…Furthermore, it is likely from the phylogenetic tree that atypical PKC was first formed by evolution from the common prototype of the AGC protein kinase family, and novel and conventional PKCs next. The relationships among mammalian PKC isoforms and PRKs 28) and that between conventional and novel PKCs and other protein kinase family have been discussed by other investigators as well, [29][30][31] and are consistent with the phylogeny of the protein kinase catalytic domains shown in Fig. 5.…”

Apoptosis in pre-Bilaterians: Hydra as a model

“…An insulin receptor homolog was cloned [63] and three insulin genes have now been identified (Steele, personal communication). It was shown that protein kinase B in Hydra has all the characterisitics to be regulated by PI(3)kinase signalling [64] and that the PI(3) kinase inhibitor wortmannin induces massive apoptosis in Hydra [65]. When a Hydra FoxO-GFP fusion protein is expressed ectopically in Hydra epithelial cells, it is partially translocated into the nucleus due to the GFP-tag [57,66].…”

A Rho-Binding Protein Kinase C-Like Activity Is Required for the Function of Protein Kinase N in Drosophila Development

“…In fact, evolutionary studies indicate that Pkns and PKCs have a common evolutionary ancestor (Herold et al 2002). In yeast, a single PKN/PKClike molecule exists that has domains similar to the ACC domains of Pkn and to the C1 and C2 domains of PKCs.…”