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1.
The CLE family of plant polypeptide signaling molecules 总被引:4,自引:0,他引:4
Polypeptide ligands have long been recognized as primary signaling molecules in diverse physiological processes in animal systems. Recent studies in plants have provided major breakthroughs with the discovery that small polypeptides are also involved in many plant biological processes, indicating that the use of polypeptides as signaling molecules in cell-to-cell communication is evolutionarily conserved. The CLAVATA3 (CLV3)/ENDOSPERM SURROUNDING REGION (ESR)-related (CLE) proteins are currently the best understood family of small polypeptides in plants. The recent isolation of MCLV3 from Arabidopsis and TDIF from a Zinnia cell culture system indicates that biologically active CLE polypeptides are produced by post-translational proteolysis and modification, similar to peptide hormone production in animals and yeast. Here, we review exciting discoveries involving the identification of the CLE proteins and their functions in various aspects of plant development, including restriction of stem cell accumulation by CLV3 and inhibition of xylem differentiation by TDIF. 相似文献
2.
D.T.A. Lamport 《Cellular and molecular life sciences : CMLS》2001,58(10):1363-1385
This review of the living cell wall [1] and its protein components is in two parts. The first is anecdotal. A personal account
spanning over 40 years research may perhaps be an antidote to one stereotypical view of scientists as detached and humorless.
The second part deals with the meaning of function, particularly as it applies to hydroxyproline-rich glycoproteins. Function
is a difficult word to define objectively. However, with help from such luminaries as Humpty Dumpty: "A word means what I
want it to mean, neither more nor less," and Wittgenstein: "Giving examples of usage ... is the only way to talk about meaning,"
it is possible to construct a ziggurat representing increasingly complex levels of organization from molecular structure to
ecology. Forty years ago I suggested that hydroxyproline-rich structural proteins played a key role in cell wall functioning.
But because the bulk of the wall is carbohydrate, there has been an understandable resistance to paradigm change. Expansins,
paradoxically, contribute greatly to this resistance because their modus operandi as cell-wall-loosening proteins is based
on the idea that they break hydrogen bonds between polysaccharide chains allowing slippage. However, this view is not consistent
with the recent discovery [Grobe et al. (1999) Eur. J. Biochem 263: 33-40] that β-expansins may be proteases, as it implies that the extensin network is not a straightjacket but a substrate for expansin
in muro. Such a direct role for extensins in both negative and positive regulation of cell expansion and elongation may constitute
a major morphogenetic mechanism operating at all levels of plant growth and development. 相似文献
3.
J. Willems 《Cellular and molecular life sciences : CMLS》1964,20(1):11-11
Summary Oriented overgrowth (epitaxy) of the needle-like crystals of pentachlorophenol on the surface of the cell walls of parenchyma is described. By means of this epitaxy it is possible to obtain an insight into the orientation of the cellulose microfibrils on the wall surface of plant cells. 相似文献
4.
Synthetic genes for the elucidation of glycosylation codes for arabinogalactan-proteins and other hydroxyproline-rich glycoproteins 总被引:5,自引:0,他引:5
Hydroxyproline-rich glycoproteins (HRGPs) are ubiquitous architectural components of the growing plant cell wall, accounting
for as much as 10-20% of the dry weight. HRGPs are implicated in all aspects of plant growth and development, including responses
to stress. The HRGP superfamily contains three major groups which represent a continuum of peptide periodicity and hydroxyproline-O-glycosylation.
These groups range from the highly periodic and lightly arabinosylated repetitive proline-rich proteins (PRPs), through the
crosslinked extensins which are periodic and highly arabinosylated, to the arabinogalactan-proteins (AGPs) which are the most
highly glycosylated and least periodic. The repetitive units are small, often only four- to six-residue-glycosylated modules
viewed hypothetically as functional motifs, or glycomodules. The Hyp contiguity hypothesis predicts that Hyp arabinosylation
increases with Hyp contiguity and that clustered noncontiguous Hyp residues are sites of arabinogalactan polysaccharide addition
in the AGPs and gums. Recent results involving glycosylation site mapping of endogenous HRGPs and HRGP design using synthetic
genes have corroborated the hypothesis. The uses of synthetic genes in HRGP glycosylation site mapping and structural/functional
analysis are also discussed. 相似文献
5.
The chloroplast is the hallmark organelle of plants. It performs photosynthesis and is therefore required for photoautotrophic
plant growth. The chloroplast is the most prominent member of a family of related organelles termed plastids which are ubiquitous
in plant cells. Biogenesis of the chloroplast from undifferentiated proplastids is induced by light. The generally accepted
endosymbiont hypothesis states that chloroplasts have arisen from an internalized cyanobacterial ancestor. Although chloroplasts
have maintained remnants of the ancestral genome (plastome), the vast majority of the genes encoding chloroplast proteins
have been transferred to the nucleus. This poses two major challenges to the plant cell during chloroplast biogenesis: First,
light and developmental signals must be interpreted to coordinately express genetic information contained in two distinct
compartments. This is to ensure supply and stoichiometry of abundant chloroplast components. Second, developing chloroplasts
must efficiently import nuclear encoded and cytosolically synthesized proteins. A subset of proteins, including such encoded
by the plastome, must further be sorted to the thylakoid compartments for assembly into the photosynthetic apparatus.
Received 1 September 2000; received after revision 27 October 2000; accepted 1 November 2000 相似文献
6.
Immunological evidence suggests that plants, like vertebrates, contain natriuretic peptides (NPs) and that rat atrial NP
(rANP) binds specifically to plant membranes and promotes concentration and conformation-dependent stomatal opening. Stomatal
opening and specific increases in cGMP levels were also observed in response to immunoreactive plant NP (irPNP). Here we report
that both 1 μM rANP and irPNP (100 ng total protein/100 μL) significantly increase radial water movements out of the xylem
of shoots of Tradescantia multiflora. Enhanced radial water movements are also observed in response to the cell permeant cGMP analogue 8-Br-cGMP (100 nM). The
water channel inhibitor mercuric chloride (HgCl2) significantly inhibits radial water movements at concentrations of 50 μM, while the presence of 10 μM 2-hydroxyethylmercaptoethanol
(ME) prevents the inhibitory effect of the mercurial. The guanylate cyclase inhibitor LY 83583 at a concentration of 20 μM
and sodium azide (NaN3) at concentrations of ≥ 1 μM both also reduce radial water movements. We therefore conclude that the regulation of radial
water movement out of the xylem involves modulation of cGMP levels, water channels and respiration-dependent processes. In
addition, we propose that NPs have a critical role to play in radial water movements out of the xylem and speculate that as
in vertebrates, NP effects might, at least in part, be mediated via the regulation of guanylate cyclases and water channels.
Received 15 June 1998; received after revision 7 August 1998; accepted 26 August 1998 相似文献
7.
This review presents plant-specific characteristics of the Golgi apparatus and discusses their impact on retention of membrane proteins in the Golgi or the trans-Golgi network (TGN). The plant Golgi consists of distinct stacks of cisternae that actively move throughout the cytoplasm. The Golgi apparatus is a very dynamic compartment and the site for maturation of N-linked glycans. It is also a factory for complex carbohydrates that are part of the cell wall. The TGN is believed to be the site from where vacuolar proteins are sorted by receptors towards each type of vacuole. To maintain the structure and specific features of the Golgi, resident proteins ought to be maintained in the proper Golgi cisternae or in the TGN. Two families of membrane proteins will be taken as examples for Golgi/TGN retention: (i) the enzymes involved in N-glycosylation processes and (ii) a vacuolar sorting receptor. Although the number of available plant proteins localized in Golgi/TGN is low, the basis of retention appears to be shared over all kingdoms and may result from pure retention and recycling mechanisms. In this review, we will summarize the characteristics of a plant Golgi and will discuss especially their consequences on on the study of this highly dynamic structure. We then choose membrane proteins with a single transmembrane domain to illustrate the signals and mechanisms involved in plants to localize and maintain proteins in the Golgi and the TGN. 相似文献
8.
Hydroxyproline-rich glycoproteins in plant reproductive tissues: structure, functions and regulation 总被引:10,自引:0,他引:10
H. Wu B. de Graaf C. Mariani A.Y. Cheung 《Cellular and molecular life sciences : CMLS》2001,58(10):1418-1429
The plant reproductive process of pollination involves a series of interactions between the male gametophyte (the pollen
grain or pollen tube) and extracellular matrix (ECM) molecules secreted by different cell types along the pollen tube growth
pathway in the female organ, the pistil. These interactions are believed to signal and regulate the pollen tube growth process
to effect successful delivery of the sperm cells to the ovules where fertilization takes place. Hydroxyproline-rich glycoproteins
secreted by plant cells are believed to play a broad range of functions, ranging from providing structural integrity to mediating
cell-cell interactions and communication. The pistil and pollen tube ECM is enriched in these highly glycosylated proteins.
Our discussions here will focus on a number of these proteins for which most information has been available, from Nicotiana tabacum, its self-incompatible relative N. alata, and Zea mays. In addition, the regulation of the synthesis and glyco-modification of one of these proteins, TTS (transmitting tissue-specific)
protein from N. tabacum will be discussed in the light of how differential glycosylation may be used to regulate molecular interactions within the
ECM. 相似文献
9.
10.
MAP kinases in plant signal transduction 总被引:10,自引:0,他引:10
Mitogen-activated protein kinase (MAPK) pathways are modules involved in the transduction of extracellular signals to intracellular
targets in all eukaryotes. Distinct MAPK pathways are regulated by different extracellular stimuli and are implicated in a
wide variety of biological processes. In plants there is evidence for MAPKs playing a role in the signaling of abiotic stresses,
pathogens and plant hormones. The large number and divergence of plant MAPKs indicates that this ancient mechanism of bioinformatics
is extensively used in plants and may provide a new molecular handle on old questions. 相似文献
11.
Alejandra A. Covarrubias Cesar L. Cuevas-Velazquez Paulette S. Romero-Pérez David F. Rendón-Luna Caspar C. C. Chater 《Cellular and molecular life sciences : CMLS》2017,74(17):3119-3147
Plants are sessile organisms. This intriguing nature provokes the question of how they survive despite the continual perturbations caused by their constantly changing environment. The large amount of knowledge accumulated to date demonstrates the fascinating dynamic and plastic mechanisms, which underpin the diverse strategies selected in plants in response to the fluctuating environment. This phenotypic plasticity requires an efficient integration of external cues to their growth and developmental programs that can only be achieved through the dynamic and interactive coordination of various signaling networks. Given the versatility of intrinsic structural disorder within proteins, this feature appears as one of the leading characters of such complex functional circuits, critical for plant adaptation and survival in their wild habitats. In this review, we present information of those intrinsically disordered proteins (IDPs) from plants for which their high level of predicted structural disorder has been correlated with a particular function, or where there is experimental evidence linking this structural feature with its protein function. Using examples of plant IDPs involved in the control of cell cycle, metabolism, hormonal signaling and regulation of gene expression, development and responses to stress, we demonstrate the critical importance of IDPs throughout the life of the plant. 相似文献
12.
Antifungal proteins: targets,mechanisms and prospective applications 总被引:15,自引:2,他引:13
All organisms have evolved several defence systems in order to protect themselves against bacteria, fungi and viruses. Higher organisms have developed a complex network of humoral and cellular responses, called adaptive immunity. A second defence system, innate immunity, was discovered in the early 1980s, consisting of small cationic peptides with a broad antimicrobial spectrum. These proteins act immediately at sites of infection or inflammation. The production of proteins with antimicrobial activity was not limited to higher organisms but was also found in insects, plants and microorganisms. During the last 2decades a broad range of proteins with very different structural features have been isolated and characterised from differing organisms ranging from bacteria to human beings. Over 500cationic membrane-acting proteins with antimicrobial and antifungal activities have been identified to date. Apart from these proteins, a very large number of antifungal proteins active on the fungal cell wall, on enzymes of the cell wall synthesis machinery, the plasma membrane and on intracellular targets have been characterised.Received 17 June 2003; received after revision 4 August 2003; accepted 18 August 2003 相似文献
13.
Sagane Y Hosp J Zech K Thompson EM 《Cellular and molecular life sciences : CMLS》2011,68(9):1611-1622
Oriented cellulose deposition is critical to plant patterning and models suggest microtubules constrain cellulose synthase
movements through the plasma membrane. Though widespread in plants, urochordates are the only animals that synthesize cellulose.
We characterized the distinctive cellulose microfibril scaffold of the larvacean house and its interaction with house structural
proteins (oikosins). Targeted disruption of cytoskeletal elements, secretory pathways, and plasma membrane organization, suggested
a working model for templating extracellular cellulose microfibrils from animal cells that shows both convergence and differences
to plant models. Specialized cortical F-actin arrays template microfibril orientation and glycosylphosphatidylinositol-anchored
proteins in lipid rafts may act as scaffolding proteins in microfibril elongation. Microtubules deliver and maintain cellulose
synthase complexes to specific cell membrane sites rather than orienting their movement through the membrane. Oikosins are
incorporated into house compartments directly above their corresponding cellular field of expression and interact with the
cellulose scaffold to a variable extent. 相似文献
14.
V. Bellotti P. Mangione M. Stoppini 《Cellular and molecular life sciences : CMLS》1999,55(6-7):977-991
The physiological metabolism of proteins guarantees that different cellular compartments contain the appropriate concentration
of proteins to perform their biological functions and, after a variable period of wear and tear, mediates their natural catabolism.
The equilibrium between protein synthesis and catabolism ensures an effective turnover, but hereditary or acquired abnormalities
of protein structure can provoke a premature loss of biological function, an accelerated catabolism and diseases caused by
the loss of an irreplaceable function. In certain proteins, abnormal structure and metabolism are associated with a strong
tendency to self-aggregation into a polymeric fibrillar structure, and in these cases the disease is not principally caused
by the loss of an irreplaceable function but by the action of this new biological entity. Amyloid fibrils are an apparently
inert, insoluble, mainly extracellular protein polymer that kills the cell without tissue necrosis but by activation of the
apoptotic mechanism. We analyzed the data reported so far on the structural and functional properties of four prototypic proteins
with well-known biological functions (lysozyme, transthyretin, β2-microglobulin and apolipoprotein AI) that are able to create
amyloid fibrils under certain conditions, with the perspective of evaluating whether the achievement of biological function
favors or inhibits the process of fibril formation. Furthermore, studying the biological functions carried out by amyloid
fibrils reveals new types of protein-protein interactions in the transmission of messages to cells and may provide new ideas
for effective therapeutic strategies.
Received 9 November 1998; received after revision 15 January 1999; accepted 15 January 1999 相似文献
15.
H. N. Poinar R. R. Melzer G. O. Poinar Jr. 《Cellular and molecular life sciences : CMLS》1996,52(4):387-390
Hymenaea protera leaflet fossils entombed in amber, dated at 30 to 40 million years (mine strata and exomethylene dating) were observed by both light and transmission electron microscopy. Ultrastructure preservation in these leaflets shows the presence of chloroplasts with thylakoid membranes, cell walls, mitochondria with associated endoplasmic reticulum, nuclei, and xylem tissue. Tissues show varying degrees of degradation; however, natural resin, which has perfused the cells, seems to maintain the structural integrity of the membranes and walls. We conclude that preservation of amber entombed organisms results from dehydration and slow fixative properties leaving the ultrastructure in excellent condition. These findings parallel reports on the exceptional preservation of amino acids and of DNA in amber-entombed organisms. 相似文献
16.
The BAG (Bcl-2 associated athanogene) family is a multifunctional group of proteins that perform diverse functions ranging from apoptosis to tumorigenesis.
An evolutionarily conserved group, these proteins are distinguished by a common conserved region known as the BAG domain.
BAG genes have been found in yeasts, plants, and animals, and are believed to function as adapter proteins forming complexes
with signaling molecules and molecular chaperones. In humans, a role for BAG proteins has been suggested in carcinogenesis,
HIV infection, and Parkinson’s disease. These proteins are therefore potential therapeutic targets, and their expression in
cells may serve as a predictive tool for such diseases. In plants, the Arabidopsis thaliana genome contains seven homologs of the BAG family, including four with domain organization similar to animal BAGs. Three members
contain a calmodulin-binding domain possibly reflecting differences between plant and animal programmed cell death. This review
summarizes current understanding of BAG proteins in both animals and plants.
Received 21 November 2007; received after revision 17 December 2007; accepted 2 January 2008 相似文献
17.
Protein folding and degradation in bacteria: to degrade or not to degrade? That is the question 总被引:11,自引:0,他引:11
In Escherichia coli protein quality control is carried out by a protein network, comprising chaperones and proteases. Central to this network
are two protein families, the AAA+ and the Hsp70 family. The major Hsp70 chaperone, DnaK, efficiently prevents protein aggregation
and supports the refolding of damaged proteins. In a special case, DnaK, together with the assistance of the AAA+ protein
ClpB, can also refold aggregated proteins. Other Hsp70 systems have more specialized functions in the cell, for instance HscA
appears to be involved in the assembly of Fe/S proteins. In contrast to ClpB, many AAA+ proteins associate with a peptidase
to form proteolytic machines which remove irreversibly damaged proteins from the cellular pool. The AAA+ component of these
proteolytic machines drives protein degradation. They are required not only for recognition of the substrate but also for
substrate unfolding and translocation into the proteolytic chamber. In many cases, specific adaptor proteins modify the substrate
binding properties of AAA+ proteins. While chaperones and proteases do not appear to directly cooperate with each other, both
systems appear to be necessary for proper functioning of the cell and can, at least in part, substitute for one another.
RID="*"
ID="*"Corresponding author. 相似文献
18.
Are elicitins cryptograms in plant-Oomycete communications? 总被引:13,自引:0,他引:13
Ponchet M Panabières F Milat M-L Mikes V Montillet JL Suty L Triantaphylides C Tirilly Y Blein JP 《Cellular and molecular life sciences : CMLS》1999,56(11-12):1020-1047
Stimulation of plant natural defenses is an important challenge in phytoprotection prospects. In that context, elicitins, which are small proteins secreted by Phytophthora and Pythium species, have been shown to induce a hypersensitive-like reaction in tobacco plants. Moreover, these plants become resistant to their pathogens, and thus this interaction constitutes an excellent model to investigate the signaling pathways leading to plant resistance. However, most plants are not reactive to elicitins, although they possess the functional signaling pathways involved in tobacco responses to elicitin. The understanding of factors involved in this reactivity is needed to develop agronomic applications. In this review, it is proposed that elicitins could interact with regulating cell wall proteins before they reach the plasma membrane. Consequently, the plant reactivity or nonreactivity status could result from the equilibrium reached during this interaction. The possibility of overexpressing the elicitins directly from genomic DNA in Pichia pastoris allows site-directed mutagenesis experiments and structure/function studies. The recent discovery of the sterol carrier activity of elicitins brings a new insight on their molecular activity. This constitutes a crucial property, since the formation of a sterol-elicitin complex is required to trigger the biological responses of tobacco cells and plants. Only the elicitins loaded with a sterol are able to bind to their plasmalemma receptor, which is assumed to be an allosteric calcium channel. Moreover, Phytophthora and Pythium do not synthesize the sterols required for their growth and their fructification, and elicitins may act as shuttles trapping the sterols from the host plants. Sequence analysis of elicitin genes from several Phytophthora species sheds unexpected light on the phylogenetic relationships among the genus, and suggests that the expression of elicitins is under tight regulatory control. Finally, general involvement of these lipid transfer proteins in the biology of Pythiaceae, and in plant defense responses, is discussed. A possible scheme for the coevolution between Phytophthora and tobacco plants is approached. 相似文献
19.
B Walles U Gr?schel-Stewart P Kannisto C Owman N O Sj?berg K Unsicker 《Experientia》1990,46(7):682-683
Actin- and myosin-like immunoreactivity is found in cells located in the theca externa of the follicle wall of the human ovary, and corresponding to previously observed myoid cells. The immunocytochemical observation provides direct structural evidence that non-vascular contractile cells are also present in the follicle wall in humans. As expected, perifollicular blood vessels showed a positive immunoreaction for actin and myosin in their smooth muscle walls. 相似文献
20.
Summary Electron micrographs were made of the cellulose part of the cell walls of pollen tubes ofPetunia hybrida, grown in selfed self-sterile plants and on agar plates. In sterile plants the tubes showed denser membranes but the orientation of the cellulose strands is the same as in cells germinated on agar. 相似文献