Arabidopsis RAB geranylgeranyl transferase β-subunit mutant is constitutively photomorphogenic, and has shoot growth and gravitropic defects

Hála, Michal; Soukupová, Hana; Synek, Lukáš; Žárský, Viktor

doi:10.1111/j.1365-313x.2010.04172.x

Cited by 26 publications

(53 citation statements)

References 77 publications

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“…3B). This altered migration is consistent with that seen in previous studies of plant and human Rab GTPases (37,63).…”

Section: Rgta1/2 and Rgtb1/2 Encoded By Two Pairs Of Paralogoussupporting

confidence: 92%

“…In the Arabidopsis genome, genes encoding two putative ␣ subunits, RGTA1 and RGTA2, and two putative ␤ subunits, RGTB1 and RGTB2, of Rab-GGT were annotated (36). rgtb1 mutants show a series of defects in shoot morphology, shoot gravitropism, tip growth of root hairs and pollen tubes, and light response (37,38). rgtb2 mutants are broadly indistinguishable from wild-type plants under normal conditions but are also defective in tip growth (38).…”

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confidence: 99%

“…Indirect evidence that RGTB1 is a bona fide Rab-GGT subunit comes from studies of rgtb1 mutants; specifically, the level of prenylated RABA2A is reduced in rgtb1 mutants, and rgtb1 total extracts cannot efficiently prenylate recombinant RABA2A in vitro (37). However, the biochemical activity of the other putative subunits and possible target specificity differences among different ␣⅐␤ combinations remain unknown.…”

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confidence: 99%

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Arabidopsis Rab Geranylgeranyltransferases Demonstrate Redundancy and Broad Substrate Specificity in Vitro

Shi

Zeng

Kunkel

et al. 2016

Journal of Biological Chemistry

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Posttranslational lipid modifications mediate the membrane attachment of Rab GTPases, facilitating their function in regulating intracellular vesicular trafficking. In Arabidopsis, most Rab GTPases have two C-terminal cysteines and potentially can be double-geranylgeranylated by heterodimeric Rab geranylgeranyltransferases (Rab-GGTs). Genes encoding two putative ␣ subunits and two putative ␤ subunits of Rab-GGTs have been annotated in the Arabidopsis thaliana genome, but little is known about Rab-GGT activity in Arabidopsis. In this study, we demonstrate that four different heterodimers can be formed between putative Arabidopsis Rab-GGT ␣ subunits RGTA1/ RGTA2 and ␤ subunits RGTB1/RGTB2, but only RGTA1⅐ RGTB1 and RGTA1⅐RGTB2 exhibit bona fide Rab-GGT activity, and they are biochemically redundant in vitro. We hypothesize that RGTA2 function might be disrupted by a 12-amino acid insertion in a conserved motif. We present evidence that Arabidopsis Rab-GGTs may have preference for prenylation of C-terminal cysteines in particular positions. We also demonstrate that Arabidopsis Rab-GGTs can not only prenylate a great variety of Rab GTPases in the presence of Rab escort protein but, unlike Rab-GGT in yeast and mammals, can also prenylate certain non-Rab GTPases independently of Rab escort protein. Our findings may help to explain some of the phenotypes of Arabidopsis protein prenyltransferase mutants.Small GTPases serve as molecular switches that shuttle between active GTP-bound and inactive GDP-bound forms, providing transient signals to downstream effectors (1, 2). In plants, many membrane-localized small GTPases are important regulators of vesicular trafficking (1). They are typically anchored to membranes via posttranslational lipid modifications (3).Rab GTPases constitute the largest family of the Ras superfamily of small GTPases (3-5). They are involved in regulating trafficking processes, such as vesicle formation, transport, membrane targeting, and docking (1, 5). The diversity and specific localization of Rab GTPases not only determine membrane identity, but also reflect the complexity of vesicle trafficking (1, 6).Phylogenetic analysis suggests that the 57 Arabidopsis Rabencoding sequences fall into just eight subfamilies (3, 6), in contrast to ϳ40 Rab subfamilies in mammals (7). Accordingly, the size of each Arabidopsis Rab subfamily is expanded. The distinct composition of the Arabidopsis Rab GTPase family suggests plant-specific functions (1, 6). Of these 57 members, 54 include two cysteines that are near the C terminus and are candidate prenylation sites (Table 1). At least one of the non-prenylated Rabs, RABF1/ARA6, is N-myristoylated and palmitoylated (8).Protein prenylation irreversibly adds one 15-carbon isoprenoid (farnesylation), one 20-carbon isoprenoid (geranylgeranylation), or two 20-carbon isoprenoids (double geranylgeranylation) to one or two C-terminal cysteine residues of target proteins, by forming thioether bonds (9, 10). These three types of prenylation are respectively catalyzed by thre...

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“…3B). This altered migration is consistent with that seen in previous studies of plant and human Rab GTPases (37,63).…”

Section: Rgta1/2 and Rgtb1/2 Encoded By Two Pairs Of Paralogoussupporting

confidence: 92%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Arabidopsis Rab Geranylgeranyltransferases Demonstrate Redundancy and Broad Substrate Specificity in Vitro

Shi

Zeng

Kunkel

et al. 2016

Journal of Biological Chemistry

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“…BRs control gravitropic bending in hypocotyls/shoots (Meudt, 1987;Park, 1998;Philosoph-Hadas et al, 2005;Nakamoto et al, 2006;Hála et al, 2010;Arteca and Arteca, 2011). BR acts synergistically with auxin during hypocotyl gravitropism of partially deetiolated bean (Phaseolus vulgaris; Meudt, 1987).…”

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confidence: 99%

Hypocotyl Directional Growth in Arabidopsis: A Complex Trait

et al. 2012

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The growth direction of the Arabidopsis (Arabidopsis thaliana) etiolated-seedling hypocotyl is a complex trait that is controlled by extrinsic signals such as gravity and touch as well as intrinsic signals such as hormones (brassinosteroid [BR], auxin, cytokinin, ethylene) and nutrient status (glucose [Glc], sucrose). We used a genetic approach to identify the signaling elements and their relationship underlying hypocotyl growth direction. BR randomizes etiolated-seedling growth by inhibiting negative gravitropism of the hypocotyls via modulating auxin homeostasis for which we designate as reset, not to be confused with the gravity set point angle. Cytokinin signaling antagonizes this BR reset of gravity sensing and/or tropism by affecting ethylene biosynthesis/signaling. Glc also antagonizes BR reset but acts independently of cytokinin and ethylene signaling pathways via inhibiting BR-regulated gene expression quantitatively and spatially, by altering protein degradation, and by antagonizing BR-induced changes in microtubule organization and cell patterning associated with hypocotyl agravitropism. This BR reset is reduced in the presence of the microtubule organization inhibitor oryzalin, suggesting a central role for cytoskeleton reorganization. A unifying and hierarchical model of Glc and hormone signaling interplay is proposed. The biological significance of BR-mediated changes in hypocotyl graviresponse lies in the fact that BR signaling sensitizes the dark-grown seedling hypocotyl to the presence of obstacles, overriding gravitropism, to enable efficient circumnavigation through soil.

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“…Duplication of 946 the rggta has been noted exclusively for Arabidopsis 947 thaliana but not for other plants (Hala et al 2010). …”

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confidence: 99%

Structure, regulation and cellular functions of Rab geranylgeranyl transferase and its cellular partner Rab Escort Protein

Gutkowska

Świeżewska

2012

Molecular Membrane Biology

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Arabidopsis RAB geranylgeranyl transferase β-subunit mutant is constitutively photomorphogenic, and has shoot growth and gravitropic defects

Cited by 26 publications

References 77 publications

Arabidopsis Rab Geranylgeranyltransferases Demonstrate Redundancy and Broad Substrate Specificity in Vitro

Arabidopsis Rab Geranylgeranyltransferases Demonstrate Redundancy and Broad Substrate Specificity in Vitro

Hypocotyl Directional Growth in Arabidopsis: A Complex Trait

Structure, regulation and cellular functions of Rab geranylgeranyl transferase and its cellular partner Rab Escort Protein

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