Protein Ser/Thr/Tyr phosphorylation in the Archaea

Abstract

The third domain of life, the Archaea (formerly Archaebacteria), is populated by a physiologically diverse set of microorganisms, many of which reside at the ecological extremes of our global environment. Although ostensibly prokaryotic in morphology, the Archaea share much closer evolutionary ties with the Eukarya than with the superficially more similar Bacteria. Initial genomic, proteomic, and biochemical analyses have revealed the presence of "eukaryotic" protein kinases and phosphatases and an intriguing set of serine-, threonine-, and tyrosine-phosphorylated proteins in the Archaea that may offer new insights into this important regulatory mechanism.

Keywords: Archaea; Archaebacteria; Evolution; Protein Kinases; Protein Phosphatase; Protein Phosphorylation.

FIGURE 1.

PPP tree. Shown is a dendrogram constructed using the sequences of assorted eukaryal (blue) and bacterial (green) PPP family protein phosphatases along with the three verified PPP family protein-serine/threonine phosphatases (red): PP1-arch1 from S. solfataricus (S. solf.) (14), PP1-arch2 from M. thermophila (M. therm.) TM-1 (15), and PyPP1 from P. abyssi TAG11 (16). PP, protein phosphatase; M. aerug., Microcystis aeruginosa.

FIGURE 2.

Known and deuced ePKs encoded by the genome of S. solfataricus P2. Shown are schematic diagrams of the known and deduced ePKs encoded by the genome of S. solfataricus (38). The identity of the ORF is given on the right along with the protein name, if any. The name of the most closely related protein kinase subfamily, as deduced from the sequence of the putative catalytic domains, is shown in parentheses using the classification scheme of Leonard et al. (3). The predicted catalytic, transmembrane, (TM), and tetratricopeptide repeat (TPR) domains are colored green, blue, and yellow, respectively. Other prospective features include winged helix-turn-helix (wHTH; red), leucine zipper (orange), methyltransferase-like (MTS; purple), and heavy metal-associated (HMA) domains.