Identification and characterization of AtI-2, an Arabidopsis homologue of an ancient protein phosphatase 1 (PP1) regulatory subunit

TY - JOUR

T1 - Identification and characterization of AtI-2, an Arabidopsis homologue of an ancient protein phosphatase 1 (PP1) regulatory subunit

AU - Templeton, George W.

AU - Nimick, Mhairi

AU - Morrice, Nicholas

AU - Campbell, David

AU - Goudreault, Marilyn

AU - Gingras, Anne-Claude

AU - Takemiya, Atsushi

AU - Shimazaki, Ken-ichiro

AU - Moorhead, Greg B. G.

PY - 2011/4/1

Y1 - 2011/4/1

N2 - PP1 (protein phosphatase 1) is among the most conserved enzymes known, with one or more isoforms present in all sequenced eukaryotic genomes. PP1 dephosphorylates specific serine/threonine phosphoproteins as defined by associated regulatory or targeting subunits. In the present study we performed a PP1-binding screen to find putative PP1 interactors in Arabidopsis thaliana and uncovered a homologue of the ancient PP1 interactor, I-2 (inhibitor-2). Bioinformatic analysis revealed remarkable conservation of three regions of plant I-2 that play key roles in binding to PP1 and regulating its function. The sequence-related properties of plant I-2 were compared across eukaryotes, indicating a lack of I-2 in some species and the emergence points from key motifs during the evolution of this ancient regulator. Biochemical characterization of AtI-2 (Arabidopsis I-2) revealed its ability to inhibit all plant PP1 isoforms and inhibitory dependence requiring the primary interaction motif known as RVXF. Arabidopsis I-2 was shown to be a phosphoprotein in vivo that was enriched in the nucleus. TAP (tandem affinity purification)-tag experiments with plant I-2 showed in vivo association with several Arabidopsis PP1 isoforms and identified other potential I-2 binding proteins.

AB - PP1 (protein phosphatase 1) is among the most conserved enzymes known, with one or more isoforms present in all sequenced eukaryotic genomes. PP1 dephosphorylates specific serine/threonine phosphoproteins as defined by associated regulatory or targeting subunits. In the present study we performed a PP1-binding screen to find putative PP1 interactors in Arabidopsis thaliana and uncovered a homologue of the ancient PP1 interactor, I-2 (inhibitor-2). Bioinformatic analysis revealed remarkable conservation of three regions of plant I-2 that play key roles in binding to PP1 and regulating its function. The sequence-related properties of plant I-2 were compared across eukaryotes, indicating a lack of I-2 in some species and the emergence points from key motifs during the evolution of this ancient regulator. Biochemical characterization of AtI-2 (Arabidopsis I-2) revealed its ability to inhibit all plant PP1 isoforms and inhibitory dependence requiring the primary interaction motif known as RVXF. Arabidopsis I-2 was shown to be a phosphoprotein in vivo that was enriched in the nucleus. TAP (tandem affinity purification)-tag experiments with plant I-2 showed in vivo association with several Arabidopsis PP1 isoforms and identified other potential I-2 binding proteins.

U2 - 10.1042/BJ20101035

DO - 10.1042/BJ20101035

M3 - Article

C2 - 21222654

SN - 0264-6021

VL - 435

SP - 73

EP - 83

JO - Biochemical Journal

JF - Biochemical Journal

ER -