Acetolactate synthases regulatory subunit and catalytic subunit genes VdILVs are involved in BCAA biosynthesis, microscletotial and conidial formation and virulence in Verticillium dahliae

Reversible phosphorylation of proteins is a post-translational modification that regulates all aspect of life through the antagonistic action of kinases and phosphatases. Protein kinases are well characterized, but protein phosphatases have been relatively neglected. Protein phosphatase 1 (PP1) catalyzes the dephosphorylation of a major fraction of phospho-serines and phospho-threonines in cells and thereby controls a broad range of cellular processes. In this review, I will discuss how phosphatases were discovered, how the view that they were unselective emerged and how recent findings have revealed their exquisite selectivity. Unlike kinases, PP1 phosphatases are obligatory heteromers composed of a catalytic subunit bound to one (or two) non-catalytic subunit(s). Based on an in-depth study of two holophosphatases, I propose the following: selective dephosphorylation depends on the assembly of two components, the catalytic subunit and the non-catalytic subunit, which serves as a high-affinity substrate receptor. Because functional complementation of the two modules is required to produce a selective holophosphatase, one can consider that they are split enzymes. The non-catalytic subunit was often referred to as a regulatory subunit, but it is, in fact, an essential component of the holoenzyme. In this model, a phosphatase and its array of mostly orphan substrate receptors constitute the split protein phosphatase system. The set of potentially generalizable principles outlined in this review may facilitate the study of these poorly understood enzymes and the identification of their physiological substrates.

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Different Regulation Modes of Calcineurin Regulatory Subunit on Its Catalytic Subunit with RII Peptide and Tau as Substrates

Protein and Peptide Letters ◽

10.2174/092986609787316243 ◽

2009 ◽

Vol 16 (2) ◽

pp. 168-172

Author(s):

Da-yu Yu ◽

Nan Qiao ◽

Ping Liu ◽

Qun Wei

Keyword(s):

Catalytic Subunit ◽

Regulatory Subunit

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Positive and Negative Regulation of Phosphoinositide 3-Kinase-Dependent Signaling Pathways by Three Different Gene Products of the p85α Regulatory Subunit

Molecular and Cellular Biology ◽

10.1128/mcb.20.21.8035-8046.2000 ◽

2000 ◽

Vol 20 (21) ◽

pp. 8035-8046 ◽

Cited By ~ 109

Author(s):

Kohjiro Ueki ◽

Petra Algenstaedt ◽

Franck Mauvais-Jarvis ◽

C. Ronald Kahn

Keyword(s):

Glucose Transport ◽

Kinase Activity ◽

Glycogen Synthesis ◽

Catalytic Subunit ◽

Regulatory Subunit ◽

Regulatory Subunits ◽

Irs Proteins ◽

Terminal Structure ◽

Stimulation Of ◽

In Cells

ABSTRACT Phosphoinositide (PI) 3-kinase is a key mediator of insulin-dependent metabolic actions, including stimulation of glucose transport and glycogen synthesis. The gene for the p85α regulatory subunit yields three splicing variants, p85α, AS53/p55α, and p50α. All three have (i) a C-terminal structure consisting of two Src homology 2 domains flanking the p110 catalytic subunit-binding domain and (ii) a unique N-terminal region of 304, 34, and 6 amino acids, respectively. To determine if these regulatory subunits differ in their effects on enzyme activity and signal transduction from insulin receptor substrate (IRS) proteins under physiological conditions, we expressed each regulatory subunit in fully differentiated L6 myotubes using adenovirus-mediated gene transfer with or without coexpression of the p110α catalytic subunit. PI 3-kinase activity associated with p50α was greater than that associated with p85α or AS53. Increasing the level of p85α or AS53, but not p50α, inhibited both phosphotyrosine-associated and p110-associated PI 3-kinase activities. Expression of a p85α mutant lacking the p110-binding site (Δp85) also inhibited phosphotyrosine-associated PI 3-kinase activity but not p110-associated activity. Insulin stimulation of two kinases downstream from PI-3 kinase, Akt and p70 S6 kinase (p70S6K), was decreased in cells expressing p85α or AS53 but not in cells expressing p50α. Similar inhibition of PI 3-kinase, Akt, and p70S6K was observed, even when p110α was coexpressed with p85α or AS53. Expression of p110α alone dramatically increased glucose transport but decreased glycogen synthase activity. This effect was reduced when p110α was coexpressed with any of the three regulatory subunits. Thus, the three different isoforms of regulatory subunit can relay the signal from IRS proteins to the p110 catalytic subunit with different efficiencies. They also negatively modulate the PI 3-kinase catalytic activity but to different extents, dependent on the unique N-terminal structure of each isoform. These data also suggest the existence of a mechanism by which regulatory subunits modulate the PI 3-kinase-mediated signals, independent of the kinase activity, possibly through subcellular localization of the catalytic subunit or interaction with additional signaling molecules.

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Roles of the catalytic subunit of cAMP-dependent protein kinase A in virulence and development of the soilborne plant pathogen Verticillium dahliae

Fungal Genetics and Biology ◽

10.1016/j.fgb.2010.01.007 ◽

2010 ◽

Vol 47 (5) ◽

pp. 406-415 ◽

Cited By ~ 65

Author(s):

Aliki Tzima ◽

Epaminondas J. Paplomatas ◽

Payungsak Rauyaree ◽

Seogchan Kang

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Verticillium Dahliae ◽

Plant Pathogen ◽

Catalytic Subunit ◽

Dependent Protein Kinase ◽

Soilborne Plant Pathogen ◽

Camp Dependent Protein Kinase ◽

Dependent Protein ◽

Kinase A

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High Glucose Exposure Promotes Activation of Protein Phosphatase 2A in Rodent Islets and INS-1 832/13 β-Cells by Increasing the Posttranslational Carboxylmethylation of Its Catalytic Subunit

Endocrinology ◽

10.1210/en.2013-1773 ◽

2014 ◽

Vol 155 (2) ◽

pp. 380-391 ◽

Cited By ~ 16

Author(s):

Daleep K. Arora ◽

Baker Machhadieh ◽

Andrea Matti ◽

Brian E. Wadzinski ◽

Sasanka Ramanadham ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Protein Phosphatase ◽

Protein Phosphatase 2A ◽

Hormone Secretion ◽

Catalytic Subunit ◽

Regulatory Subunit ◽

Cellular Functions ◽

Phosphatase 2A ◽

Normal Rat

Existing evidence implicates regulatory roles for protein phosphatase 2A (PP2A) in a variety of cellular functions, including cytoskeletal remodeling, hormone secretion, and apoptosis. We report here activation of PP2A in normal rat islets and insulin-secreting INS-1 832/13 cells under the duress of hyperglycemic (HG) conditions. Small interfering RNA-mediated knockdown of the catalytic subunit of PP2A (PP2Ac) markedly attenuated glucose-induced activation of PP2A. HG, but not nonmetabolizable 3-O-methyl glucose or mannitol (osmotic control), significantly stimulated the methylation of PP2Ac at its C-terminal Leu-309, suggesting a novel role for this posttranslational modification in glucose-induced activation of PP2A. Moreover, knockdown of the cytosolic leucine carboxymethyl transferase 1 (LCMT1), which carboxymethylates PP2Ac, significantly attenuated PP2A activation under HG conditions. In addition, HG conditions, but not 3-O-methyl glucose or mannitol, markedly increased the expression of LCMT1. Furthermore, HG conditions significantly increased the expression of B55α, a regulatory subunit of PP2A, which has been implicated in islet dysfunction under conditions of oxidative stress and diabetes. Thapsigargin, a known inducer of endoplasmic reticulum stress, failed to exert any discernible effects on the carboxymethylation of PP2Ac, expression of LCMT1 and B55α, or PP2A activity, suggesting no clear role for endoplasmic reticulum stress in HG-induced activation of PP2A. Based on these findings, we conclude that exposure of the islet β-cell to HG leads to accelerated PP2A signaling pathway, leading to loss in glucose-induced insulin secretion.

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Candida albicans Lacking the Gene Encoding the Regulatory Subunit of Protein Kinase A Displays a Defect in Hyphal Formation and an Altered Localization of the Catalytic Subunit

Eukaryotic Cell ◽

10.1128/ec.3.1.190-199.2004 ◽

2004 ◽

Vol 3 (1) ◽

pp. 190-199 ◽

Cited By ~ 57

Author(s):

Alejandro Cassola ◽

Marc Parrot ◽

Susana Silberstein ◽

Beatrice B. Magee ◽

Susana Passeron ◽

...

Keyword(s):

Candida Albicans ◽

Protein Kinase ◽

Fusion Protein ◽

Protein Kinase A ◽

Double Mutant ◽

Catalytic Subunit ◽

Regulatory Subunit ◽

Wild Type ◽

Gfp Fusion Protein ◽

Kinase A

ABSTRACT The fungal pathogen Candida albicans switches from a yeast-like to a filamentous mode of growth in response to a variety of environmental conditions. We examined the morphogenetic behavior of C. albicans yeast cells lacking the BCY1 gene, which encodes the regulatory subunit of protein kinase A. We cloned the BCY1 gene and generated a bcy1 tpk2 double mutant strain because a homozygous bcy1 mutant in a wild-type genetic background could not be obtained. In the bcy1 tpk2 mutant, protein kinase A activity (due to the presence of the TPK1 gene) was cyclic AMP independent, indicating that the cells harbored an unregulated phosphotransferase activity. This mutant has constitutive protein kinase A activity and displayed a defective germinative phenotype in N-acetylglucosamine and in serum-containing medium. The subcellular localization of a Tpk1-green fluorescent protein (GFP) fusion protein was examined in wild-type, tpk2 null, and bcy1 tpk2 double mutant strains. The fusion protein was observed to be predominantly nuclear in wild-type and tpk2 strains. This was not the case in the bcy1 tpk2 double mutant, where it appeared dispersed throughout the cell. Coimmunoprecipitation of Bcy1p with the Tpk1-GFP fusion protein demonstrated the interaction of these proteins inside the cell. These results suggest that one of the roles of Bcy1p is to tether the protein kinase A catalytic subunit to the nucleus.

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Methylated C-terminal leucine residue of PP2A catalytic subunit is important for binding of regulatory Bα subunit

Biochemical Journal ◽

10.1042/bj3390241 ◽

1999 ◽

Vol 339 (2) ◽

pp. 241-246 ◽

Cited By ~ 77

Author(s):

Jeffrey C. BRYANT ◽

Ryan S. WESTPHAL ◽

Brian E. WADZINSKI

Keyword(s):

Catalytic Subunit ◽

Regulatory Subunit ◽

Post Translational Modification ◽

Regulatory Subunits ◽

Leucine Residue ◽

Cell Extracts ◽

C Subunit ◽

Phosphatase 2A ◽

A Subunit

Methylation of the C-terminal leucine residue (Leu309) of protein serine/threonine phosphatase 2A catalytic subunit (PP2AC) is known to regulate catalytic activity in vitro, but the functional consequence(s) of this post-translational modification in the context of the cell remain unclear. Alkali-induced demethylation of PP2AC in purified PP2A heterotrimer (ABαC), but not in purified PP2A heterodimer (AC), indicated that a larger fraction of PP2AC is carboxymethylated in ABαC than in AC. To explore the role of Leu309 in PP2A holoenzyme assembly, epitope-tagged PP2A catalytic subunit (HA-PP2A) and a mutant of HA-PP2A containing an alanine residue in place of Leu309 (HA-PP2A-L309A) were transiently expressed in COS cells. Both recombinant proteins exhibited serine/threonine phosphatase activity when immunoisolated from COS cell extracts. HA-PP2A, but not HA-PP2A-L309A, was carboxymethylated in vitro. A chromatographic analysis of cell extracts indicated that most endogenous PP2AC and HA-PP2A were co-eluted with the A and Bα regulatory subunits of PP2A, whereas most HA-PP2A-L309A seemed to elute with the A subunit as a smaller complex or, alternatively, as free catalytic (C) subunit. The A subunit co-immunoisolated with both tagged proteins; however, substantially less Bα subunit co-immunoisolated with HA-PP2A-L309A than with HA-PP2A. These results demonstrate that the reversibly methylated C-terminal leucine residue of PP2AC is important for Bα regulatory subunit binding. Furthermore, the results provide evidence for an interrelationship between PP2AC carboxymethylation and PP2A holoenzyme assembly.

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