Chemistry: molecular biology and microbiology – Plant cell or cell line – per se ; composition thereof;... – Plant cell or cell line – per se – contains exogenous or...
Reexamination Certificate
2000-11-29
2003-10-14
Bui, Phuong T. (Department: 1638)
Chemistry: molecular biology and microbiology
Plant cell or cell line, per se ; composition thereof;...
Plant cell or cell line, per se, contains exogenous or...
C800S295000, C536S023100, C536S023600, C536S023200, C435S320100
Reexamination Certificate
active
06632669
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to plant growth and development and more specifically to identification of novel plant kinases and methods of identifying compounds that modulate the activity of such kinases in plants.
2. Description of the Related Art
Phosphorylation by protein kinases is one of the most common and important regulatory mechanisms in signal transmission. Plant genomes encode many protein kinases. Some of the plant kinases are homologues of kinases found in animals and fungi, while others have novel structures. Kinases comprise the largest known protein group, a super family of enzymes with widely varied functions and specificities. Kinases covalently modify proteins and peptides by the attachment of a phosphate group to one or more sites on the substrate protein.
Many of the known protein kinases use adenosine triphosphate (ATP) as the phosphate donor and place the gamma phosphate from the ATP onto an acceptor amino acid. The amino acids that can act as acceptors of the gamma phosphate group are Serine (Ser), Theronine (Thr), Tyrosine (Tyr), or Histidine (His). The majority of protein kinases known can be categorized as either Ser/Thr kinases or Tyr kinases. The Histidine kinases, originally identified in bacterial two-component systems, have recently been found as part of signaling pathways in plants and fungi.
Protein kinases can be further subdivided into families based on the amino acid sequences surrounding or inserted into the kinase catalytic domain. The function of these sequences surrounding the catalytic domain have been shown to allow regulation of the kinase as it recognizes its target substrate protein (Hardie, G and Hanks, S. (1995) The Protein Kinase Facts Books, Vol I:7-20 Academic Press, San Diego, Calif.).
The primary structure of the kinase catalytic domain is conserved and can be further subdivided into 11 subdomains. Each of these 11 subdomains contains sequence motifs that are highly conserved or invariant (Hardie, G and Hanks, S. (1995) The Protein Kinase Facts Books, Vol I:7-20 Academic Press, San Diego, Calif.). One such motif found in kinases identified to date is an invariable domain comprising asparagine, phenylalanine and glycine residues (DFG domain) surrounded by several conserved residues (Hunter T., (1997) Philos Trans R Soc Lond B Biol Sci. 353(1368):583-605, Hunter T. (1995) Cell. 80(2):225-36; van der Geer P, et al. (1994) Annu Rev Cell Biol. 10:251-337).
Studies have shown that kinases are key regulators of many cellular functions, such as: cell proliferation, cell differentiation, signal transduction, transcriptional regulation, cell motility, and cell division. Few, if any physiological processes exist in eukaryotes that are not dependent on phosphorylation.
Of particular importance in intracellular signaling are the mitogen-activated protein kinases (MAPKs). MAPKs are also members of the Ser/Thr family of protein kinases. MAPKs play a central role in the transduction of diverse extracellular stimuli, including signals that regulate development and differentiation, into intracellular responses in yeast and animals cells via phosphorylation cascades. Homologues of the MAPKs found in animals and yeast have been found in plants. Previous studies have suggested the involvement of MAP kinase cascades in the regulation of auxin signaling. In vitro phosphorylation of a bacterially produced Arabidopsis MAP kinase by a tobacco cell extract is three to four-fold more effective after treatment of protoplasts with the synthetic auxin 2,4-D, as compared to extracts from auxin-starved cultures (Mizoguchi et al. (1994) Plant J. 5:111-122). The importance of MAP kinase phosphorylation has also been demonstrated by over-expression in maize protoplasts of the catalytic domain of the tobacco MAPKK kinase NPK1, which blocks transcription from the auxin-responsive GH3 promoter (Kovtun et al. (1998) Nature 395:716-720). A role for protein phosphorylation in auxin transport has also been inferred from the discovery that the Arabidopsis gene ROOTS CURL IN NPA 1 (RCN1) encodes a regulatory subunit of protein phosphatase 2A (Garbers et al. (1996) EMBO J. 15:2115-2124).
Plant growth and development are governed by complex interactions between environmental signals and internal factors. Light regulates many developmental processes throughout the plant life cycle, from seed germination to floral induction (Chory,
J. Trends Genet.,
9:167, 1993; McNellis and Deng,
Plant Cell,
7:1749, 1995), and causes profound morphological changes in young seedlings. In the presence of light, hypocotyl growth is inhibited, cotyledons expand, leaves develop, chloroplasts differentiate, chlorophylls are produced, and many light-inducible genes are coordinately expressed. It has been suggested that plant hormones, which are known to affect the division, elongation, and differentiation of cells, are directly involved in the response of plants to light signals (P. J. Davies,
Plant Hormones: Physiology, Biochemistry and Molecular Biology
, pp 1-836, 1995; Greef and Freddericq,
Photomorphogenesis, pp
401-427, 1983). The interactions between phototransduction pathways and plant hormones however are not well understood.
Auxin is one of the classical plant hormones and regulates many aspects of plant development, including cell division, cell elongation and cell differentiation in both the root and the shoot of plants (M. Estelle,
Bioessays
14:439-44, 1992 and L. Hobbie et al.,
Plant Mol. Biol.
26:1499-519, 1994). For example, apical dominance as well as lateral root growth are under auxin control, and manipulation of auxin signaling can be used to affect growth of both the shoot and the root system.
From its point of synthesis at the plant apex (Davies, P. J. (1995) The plant hormones: Their nature, occurrence, and functions. In Plant Hormones: Physiology, Biochemistry and Molecular Biology, P. J. Davies, ed. (Netherlands: Kluwer Academic Publishers), pp. 1-12), the phytohormone auxin is directionally transported through the plant body to effect an astonishing variety of morphological processes. Auxin is required early in development to establish the bilateral axis of the developing embryo Hadfi et al. (1998) Development 125:879-887). Later, auxin participates in vascular element patterning and differentiation (Aloni, R. (1995). Biochemistry and Molecular Biology, P. J. Davies, ed. (Netherlands: Kluwer Academic Publishers), pp. 531-545), lateral organ outgrowth in the root and shoot (Okada et al. (1 991) Plant Cell 3:677-684; Celenza et al. (1995) Genes Dev. 9:2131-2142), and local growth responses to external stimuli such as light and gravity (Kaufman et al. (1995). Hormones and the orientation of growth. In Plant Hormones: Physiology, Biochemistry and Molecular Biology, P. J. Davies, ed. (Netherlands: Kluwer Academic), pp. 547-570).
While an understanding of the mechanisms of auxin action at the molecular level is preliminary, genetic and biochemical approaches have begun to reveal discrete aspects of auxin transport, signaling and response. Two related Arabidopsis proteins, PINFORMED (PIN) and ETHYLENE INSENSITIVE ROOT 1 (EIR1)/AGRAVITROPIC1 (AGR1)/PIN2, which share homology with bacterial membrane transporters, function as auxin efflux carriers in the shoot and root, respectively (Chen et al. (1998) Proc. Natl. Acad. Sci. USA 95:15112-15117; Gälweiler et al. (1998) Science 282:2226-2230; Luschnig et al. (1998) Genes Dev. 12:2175-2187; Müller et al. (1998) EMBO J. 17:6903-6911). The auxin influx carrier AUXIN INSENSITIVE 1 (AUX1), which shares homology with plant and fungal amino acid permeases, functions in root gravitropism (Bennett et al. (1996) Science 273:948-950; Marchant et al. (1999) EMBO J. 18:2066-2073). TRANSPORT INHIBITOR RESPONSE 3 (TIR3) has been implicated in auxin transport in both the root and the shoot. tir3 mutants have fewer binding sites than wild type for the auxin transport inhibitor NPA (naphthylphthalamic acid), suggesting that the TIR3 gene product either encodes or regulates
Chory Joanne
Christensen Susan K.
Weigel Detlef
Baum Stuart F.
Bui Phuong T.
Knobbe Martens Olson & Bear LLP
The Salk Institute for Biological Studies
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