A novel subfamily of monomeric inorganic pyrophosphatases in photosynthetic eukaryotes

Abstract

Two sPPases (soluble inorganic pyrophosphatases, EC 3.6.1.1) have been isolated from the microalga Chlamydomonas reinhardtii. Both are monomeric proteins of organellar localization, the chloroplastic sPPase I [Cr (Ch. reinhardtii)-sPPase I, 30 kDa] is a major isoform and slightly larger protein than the mitochondrial sPPase II (Cr-sPPase II, 24 kDa). They are members of sPPase family I and are encoded by two different cDNAs, as demonstrated by peptide mass fingerprint analysis. Molecular phylogenetic analyses indicated that Cr-sPPase I is closely related to other eukaryotic sPPases, whereas Cr-sPPase II resembles its prokaryotic counterparts. Chloroplastic sPPase I may have replaced a cyanobacterial ancestor very early during plastid evolution. Cr-sPPase II orthologues are found in members of the green photosynthetic lineage, but not in animals or fungi. These two sPPases from photosynthetic eukaryotes are novel monomeric family I sPPases with different molecular phylogenies and cellular localizations.

Inorganic Pyrophosphatase Defects Lead to Cell Cycle Arrest and Autophagic Cell Death through NAD+ Depletion in Fermenting Yeast

“…Proteins were separated by SDS-PAGE using standard procedures. Proteins were then transferred to nitrocellulose filters and probed with antibodies raised against the sPPase PPA I from the microalga Chlamydomonas reinhardtii (14) or a commercial anti-GFP antibody (Clontech, catalog number 632460). Proteins were visualized on x-ray films using horseradish peroxi-dase-coupled secondary antibodies and a chemiluminescence kit (Millipore, catalog number WBKLS0100).…”

“…Thus, cytosolic levels of this protein have been shown to be increased in several proteomics studies dealing with cancer tissues from different origins, such as lung and colon (12,13). In addition, plants have a very intricate PP i metabolism: they possess a number of structurally and catalytically diverse PP i -utilizing proteins like the membrane-bound H ϩ -PPases, several PP i -dependent glycolytic enzymes, and multiple sPPase isoforms (2,3,14). It has been observed that photosynthetic carbon assimilation and plant metabolism in general are greatly affected by changes in the levels of soluble PPases (15)(16)(17).…”

Triphosphate Tunnel Metalloenzyme Function in Senescence Highlights a Biological Diversification of This Protein Superfamily

“…While yeast and animals possess mitochondrial PPases (Lundin et al, 1991;Curbo et al, 2006), so far no mitochondrial PPase has been identified in plants. But generally PPases remove pyrophosphate (PP i ) that is created as a byproduct of anabolic processes such as nucleic acid, protein, and carbohydrate synthesis (Gómez-García et al, 2006). Removal of PP i is necessary to prevent the inhibition of thermodynamically unfavorable reactions (Maeshima 2000).…”

Roles of the vacuolar H⁺-PPase in seed storage oil mobilization and plant development

“…However, the Arabidopsis genome possesses six sPPase genes: AtPPa1 through AtPPa6, which correspond to At1g01050, At2g18230, At2g46860, At3g53620, At4g01480, and At5g09650, respectively (Meyer et al 2012, Ferjani et al 2014. These homologs are subdivided into prokaryotic (AtPPa1 to AtPPa5) and eukaryotic types (AtPPa6) (Rojas-Beltrán et al 1999, Gómez-García et al 2006. Despite being soluble, these enzymes share common features with the vacuolar H + -PPase, such as their requirement for Mg 2+ for activity.…”