Protein Ser/Thr phosphatases with kelch-like repeat domains

Area of Science:

• Biochemistry
• Molecular Biology
• Plant Science

Background:

• Protein Ser/Thr phosphatases are crucial enzymes involved in cellular regulation.
• The PPP family includes important phosphatases, but novel members with unique structures are continually being discovered.

Purpose of the Study:

• To identify and characterize novel protein phosphatases in plants.
• To investigate the evolutionary origins and structural features of these newly identified phosphatases.

Main Methods:

• Bioinformatic analysis of plant genomes.
• Sequence homology searches against known phosphatases.
• Analysis of protein domain structures and repeat motifs.

Main Results:

• Identified plant homologues of Plasmodium falciparum PfPPalpha phosphatase.
• Discovered large N-terminal domains with tandem kelch-like repeats in these plant phosphatases.
• Proposed a new classification: PPKLs (protein phosphatases with kelch-like repeat domains).
• Found four PPKL isoforms in Arabidopsis thaliana, with at least three being expressed.
• Determined PPKLs are ubiquitous in Viridiplantae.

Conclusions:

• PPKLs represent a novel group of plant protein phosphatases with unique N-terminal kelch-like repeat domains.
• These domains likely mediate protein-protein interactions via beta-propeller structures.
• The presence of PPKLs in both Viridiplantae and Apicomplexa supports endosymbiotic theories regarding Apicomplexa's origin from red algae.