F-Actin Organization and Pollen Tube Tip Growth in Arabidopsis Are Dependent on the Gametophyte-Specific Armadillo Repeat Protein ARO1

AbstractPollen tube elongation is characterized by a highly-polarized tip growth process dependent on an efficient vesicular transport system and largely mobilized by actin cytoskeleton. Pollen tubes are an ideal model system to study exocytosis, endocytosis, membrane recycling, and signaling network coordinating cellular processes, structural organization and vesicular trafficking activities required for tip growth. Proteomic analysis was applied to identifyNicotiana tabacumDifferentially Abundant Proteins (DAPs) after in vitro pollen tube treatment with membrane trafficking inhibitors Brefeldin A, Ikarugamycin and Wortmannin. Among roughly 360 proteins separated in two-dimensional gel electrophoresis, a total of 40 spots visibly changing between treated and control samples were identified by MALDI-TOF MS and LC–ESI–MS/MS analysis. The identified proteins were classified according to biological processes, and most proteins were related to pollen tube energy metabolism, including ammino acid synthesis and lipid metabolism, structural features of pollen tube growth as well modification and actin cytoskeleton organization, stress response, and protein degradation. In-depth analysis of proteins corresponding to energy-related pathways revealed the male gametophyte to be a reliable model of energy reservoir and dynamics.

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The Pollen Tube Oscillator: Towards a Molecular Mechanism of Tip Growth?

Fertilization in Higher Plants ◽

10.1007/978-3-642-59969-9_22 ◽

1999 ◽

pp. 317-336 ◽

Cited By ~ 6

Author(s):

J. A. Feijó

Keyword(s):

Pollen Tube ◽

Molecular Mechanism ◽

Tip Growth

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δ-Catenin/NPRAP (neural plakophilin-related armadillo repeat protein) interacts with and activates sphingosine kinase 1

Biochemical Journal ◽

10.1042/bj20040141 ◽

2004 ◽

Vol 382 (2) ◽

pp. 717-723 ◽

Cited By ~ 39

Author(s):

Toshitada FUJITA ◽

Taro OKADA ◽

Shun HAYASHI ◽

Saleem JAHANGEER ◽

Noriko MIWA ◽

...

Keyword(s):

Cell Motility ◽

Hippocampal Neurons ◽

Mdck Cells ◽

Specific Inhibitor ◽

Sphingosine Kinase ◽

Dependent Manner ◽

Repeat Protein ◽

Sphingosine 1 Phosphate ◽

Key Enzyme ◽

Armadillo Repeat

Sphingosine kinase (SPHK) is a key enzyme catalysing the formation of sphingosine 1-phosphate (SPP), a lipid messenger that is implicated in the regulation of a wide variety of important cellular events acting through intracellular, as well as extracellular, mechanisms. However, the molecular mechanism of intracellular actions of SPP remains unclear. Here, we have identified δ-catenin/NPRAP (neural plakophilin-related armadillo repeat protein) as a potential binding partner for SPHK1 by yeast two-hybrid screening. From co-immunoprecipitation analyses, the C-terminal portion of δ-catenin/NPRAP containing the seventh to tenth armadillo repeats was found to be required for interaction with SPHK1. Endogenous δ-catenin/NPRAP was co-localized with endogenous SPHK1 and transfected δ-catenin/NPRAP was co-localized with transfected SPHK1 in dissociated rat hippocampal neurons. MDCK (Madin–Darby canine kidney) cells stably expressing δ-catenin/NPRAP contained elevated levels of intracellular SPP. In a purified system δ-catenin/NPRAP stimulated SPHK1 in a dose-dependent manner. Furthermore, δ-catenin/NPRAP-induced increased cell motility in MDCK cells was completely inhibited by dimethylsphingosine, a specific inhibitor of SPHK1. These results strongly suggest that at least some of δ-catenin/NPRAP functions, including increased cell motility, are mediated by an SPHK–SPP signalling pathway.

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Ca2+-Activated Reactive Oxygen Species Production by Arabidopsis RbohH and RbohJ Is Essential for Proper Pollen Tube Tip Growth

The Plant Cell ◽

10.1105/tpc.113.120642 ◽

2014 ◽

Vol 26 (3) ◽

pp. 1069-1080 ◽

Cited By ~ 130

Author(s):

Hidetaka Kaya ◽

Ryo Nakajima ◽

Megumi Iwano ◽

Masahiro M. Kanaoka ◽

Sachie Kimura ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Pollen Tube ◽

Reactive Oxygen Species Production ◽

Tip Growth ◽

Reactive Oxygen ◽

Oxygen Species ◽

Species Production

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Signaling in Pollen Tube Growth: Beyond the Tip of the Polarity Iceberg

Plants ◽

10.3390/plants8060156 ◽

2019 ◽

Vol 8 (6) ◽

pp. 156 ◽

Cited By ~ 4

Author(s):

Nolan Scheible ◽

Andrew McCubbin

Keyword(s):

Pollen Tube ◽

Signaling Pathways ◽

Pollen Tube Growth ◽

Tip Growth ◽

Holistic Approach ◽

Pollen Tubes ◽

Small Gtpase ◽

Tube Growth ◽

Concerted Action ◽

Current State

The coordinated growth of pollen tubes through floral tissues to deliver the sperm cells to the egg and facilitate fertilization is a highly regulated process critical to the Angiosperm life cycle. Studies suggest that the concerted action of a variety of signaling pathways underlies the rapid polarized tip growth exhibited by pollen tubes. Ca2+ and small GTPase-mediated pathways have emerged as major players in the regulation of pollen tube growth. Evidence suggests that these two signaling pathways not only integrate with one another but also with a variety of other important signaling events. As we continue to elucidate the mechanisms involved in pollen tube growth, there is a growing importance in taking a holistic approach to studying these pathways in order to truly understand how tip growth in pollen tubes is orchestrated and maintained. This review considers our current state of knowledge of Ca2+-mediated and GTPase signaling pathways in pollen tubes, how they may intersect with one another, and other signaling pathways involved. There will be a particular focus on recent reports that have extended our understanding in these areas.

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A Gain-of-Function Mutation of Arabidopsis Lipid Transfer Protein 5 Disturbs Pollen Tube Tip Growth and Fertilization

The Plant Cell ◽

10.1105/tpc.109.070854 ◽

2009 ◽

Vol 21 (12) ◽

pp. 3902-3914 ◽

Cited By ~ 70

Author(s):

Keun Chae ◽

Chris A. Kieslich ◽

Dimitrios Morikis ◽

Seung-Chul Kim ◽

Elizabeth M. Lord

Keyword(s):

Pollen Tube ◽

Tip Growth ◽

Lipid Transfer Protein ◽

Lipid Transfer ◽

Gain Of Function ◽

Transfer Protein

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Chlamydomonas ARMC2/PF27 is an obligate cargo adapter for IFT of radial spokes

10.1101/2021.10.31.466660 ◽

2021 ◽

Author(s):

Karl F Lechtreck ◽

Yi Liu ◽

Jin Dai ◽

Rama Alkhofash ◽

Jack Butler ◽

...

Keyword(s):

Lung Function ◽

Male Infertility ◽

Cell Body ◽

Intraflagellar Transport ◽

Proximal Region ◽

Repeat Protein ◽

Radial Spokes ◽

Armadillo Repeat ◽

Dynein Arms

Intraflagellar transport (IFT) carries proteins into flagella but how IFT trains interact with the large number of diverse proteins required to assemble flagella remains largely unknown. Here, we show that IFT of radial spokes in Chlamydomonas requires ARMC2/PF27, a conserved armadillo repeat protein associated with male infertility and reduced lung function. Chlamydomonas ARMC2 was highly enriched in growing flagella and tagged ARMC2 and the spoke protein RSP3 comigrated on anterograde trains. In contrast, a cargo and an adapter of inner and outer dynein arms moved independently of ARMC2, indicating that unrelated cargoes distribute stochastically onto the IFT trains. After concomitant unloading at the flagellar tip, RSP3 attached to the axoneme whereas ARMC2 diffused back to the cell body. In armc2/pf27 mutants, IFT of radial spokes was abolished and the presence of radial spokes was limited to the proximal region of flagella. We conclude that ARMC2 is a cargo adapter required for IFT of radial spokes to ensure their assembly along flagella. ARMC2 belongs to a growing class of cargo-specific adapters that enable flagellar transport of preassembled axonemal substructures by IFT.

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Peptide binding affinity redistributes preassembled repeat protein fragments

Biological Chemistry ◽

10.1515/hsz-2018-0355 ◽

2019 ◽

Vol 400 (3) ◽

pp. 395-404

Author(s):

Erich Michel ◽

Andreas Plückthun ◽

Oliver Zerbe

Keyword(s):

Protein Complexes ◽

Population Analysis ◽

Variable Number ◽

Protein Fragments ◽

Repeat Protein ◽

Target Peptide ◽

Repeat Proteins ◽

Armadillo Repeat ◽

Conformational Rearrangements ◽

Peptide Binding Affinity

Abstract Designed armadillo repeat proteins (dArmRPs) are modular peptide binders composed of N- and C-terminal capping repeats Y and A and a variable number of internal modules M that each specifically recognize two amino acids of the target peptide. Complementary fragments of dArmRPs obtained by splitting the protein between helices H1 and H2 of an internal module show conditional and specific assembly only in the presence of a target peptide (Michel, E., Plückthun, A., and Zerbe, O. (2018). Peptide-guided assembly of repeat protein fragments. Angew. Chem. Int. Ed. 57, 4576–4579). Here, we investigate dArmRP fragments that already spontaneously assemble with high affinity, e.g. those obtained from splits between entire modules or between helices H2 and H3. We find that the interaction of the peptide with the assembled fragments induces distal conformational rearrangements that suggest an induced fit on a global protein level. A population analysis of an equimolar mixture of an N-terminal and three C-terminal fragments with various affinities for the target peptide revealed predominant assembly of the weakest peptide binder. However, adding a target peptide to this mixture altered the population of the protein complexes such that the combination with the highest affinity for the peptide increased and becomes predominant when adding excess of peptide, highlighting the feasibility of peptide-induced enrichment of best binders from inter-modular fragment mixtures.

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Pollination Sub-Systems Distinguished by Pollen Tube Arrest after Incompatible Interspecific Crosses in Rhododendron (Ericaceae)

Journal of Cell Science ◽

10.1242/jcs.53.1.255 ◽

1982 ◽

Vol 53 (1) ◽

pp. 255-277

Author(s):

ELIZABETH G. WILLIAMS ◽

BRUCE R. KNOX ◽

JOHN L. ROUSE

Keyword(s):

Pollen Tube ◽

Tip Growth ◽

Interspecific Cross ◽

Embryo Sac ◽

Epifluorescence Microscopy ◽

Interspecific Crosses ◽

Abnormal Behaviour ◽

Callose Deposition ◽

Variable Diameter ◽

Stigmatic Exudate

The cytology of compatible and interspecific incompatible pollinations has been followed in selected species of the genus Rhododendron (Ericaceae). Pollinated pistils were fixed, cleared, stained in decolourized aniline blue, and observed by epifluorescence microscopy. Ten different abnormalities of arrested pollen tube tips have been detected, including burst, tapered, swollen, coiled, spiralling, spiky and variable diameter syndromes. A series of five errors of callose deposition in incompatible tubes has also been defined. Six different regions in the pistil for expression of pollen tube arrest have been found, including the stigmatic exudate, the mucilage of the upper and lower style canal, the ovary loculus, the micropyle. There may also be abnormal behaviour after entry into the embryo sac. Both the site of pollen tube arrest within the pistil, and the error syndrome of tip growth and callose deposition anomalies, are characteristic of each interspecific cross. These results are discussed in relation to the genetic control of reproduction.

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