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排序方式: 共有162条查询结果,搜索用时 31 毫秒
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Nataliya Kovalchuk Ming Li Finni Wittek Nicolas Reid Rohan Singh Neil Shirley Ainur Ismagul Serik Eliby Alex Johnson † rew S. Milligan ‡ Maria Hrmova Peter Langridge Sergiy Lopato 《Plant biotechnology journal》2010,8(1):47-64
Engineering of plant protection in cereals requires well characterized tissue-specific and wounding/pathogen-inducible promoters for targeted expression of pathogen responsive and resistance genes. We describe the isolation of seven wheat and rice defensin genes expressed in early developing grain and during grain germination, two developmental stages that are particularly vulnerable to pathogens and insects. Comparison of three-dimensional (3D) models of these rice and wheat PRPI defensins indicated variations in spatial architectures that could reflect their functional diversities. Wheat and rice were stably transformed with promoter–GUS fusion constructs and the spatial and temporal activities of four promoters were studied using whole-mount and histological assays. PRPI promoters were active before and at anthesis in both transgenic wheat and rice with activity mainly in the ovary. In rice, GUS activity was also observed in vascular tissue of the lemma, palea and anthers. After fertilization, GUS was strongly expressed in the outer cell layers of the pericarp and in the main vascular bundle of the grain. During, and a short time after, seed germination, wheat promoters were active in transgenic rice embryos, roots and/or coleoptiles. All wheat and rice promoters were strongly induced by wounding in leaf, stem and grain of transgenic rice plants. These results suggest that PRPI promoters will be useful for specific targeting and accumulation of proteins conferring resistance to pathogens in vulnerable tissues of developing and germinating grain. 相似文献
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The mammalian defensin molecule is a short, highly cationic peptide cytotoxic to both microbial and mammalian cells which
is cleaved from a precursor including a signal peptide and a highly anionic propiece. A phylogenetic analysis of 28 complete
sequences from five mammalian species (mouse, rat, guinea pig, rabbit, and human) showed species-specific clusters of sequences,
indicating that the genes duplicated after divergence of these species. Comparison of rates of synonymous and nonsynonymous
nucleotide substitution suggested that gene duplication has often been followed by a period in which diversification of the
mature defensins at the amino acid level has been selectively favored. In some comparisons, it appeared that amino acid differences
in this region have appeared in a nonrandom fashion so as to change the pattern of residue charges. Because it has been hypothesized
that the negative charge in the propiece serves to balance the positive charge in the mature defensin and thus to prevent
cytotoxicity prior to cleavage, we used a maximum likelihood method of reconstructing ancestral states in order to test whether
this balance has been maintained over evolutionary time in spite of rapid diversification of the mature defensin at the amino
acid level. Reconstructed ancestral sequences always maintained a charge balance between mature defensin and propiece, and
changes in the net positive charge of the mature defensin were balanced by corresponding changes in the propiece. The results
support the hypothesis that, in the evolution of these proteins, amino acid changes have occurred in a coordinated fashion
so as to preserve an adaptive phenotype.
Received: 23 October 1996 / Accepted: 7 January 1997 相似文献
25.
In addition to their role in sperm maturation, recent evidence has indicated that epididymal proteins have a role in male
reproductive tract innate immunity. Herein we demonstrate that human and macaque epididymal protein isoforms in the SPAG (sperm
associated antigen) 11 family, full length SPAG11C, K and L exhibit potent antibacterial activity against E. coli. Analysis of activities of the N- and C-terminal domains revealed that the human N-terminal peptide is bactericidal, while
the C-terminal domains that contain the defensin-like 6 cysteine array in SPAG11C and partial arrays in SPAG11K and SPAG11L,
lack antibacterial activity. The N-terminal peptide does not appear to contain all the determinants of activity since full-length
human SPAG11C is more active than the isolated N-terminal peptide and since sulfhydryl reduction and alkylation, which would
affect primarily the C-terminal peptides, completely abolished activities of the whole proteins. These results suggest that
the structure conferred by the disulfide bonds in human SPAG11C contributes to the antibacterial activity of the whole molecule.
The activities of the N-terminal peptide and of full length human SPAG11C were somewhat reduced in increasing NaCl concentrations.
In contrast, the antibacterial activities of full length macaque SPAG11C, K and L were unaffected by the presence of NaCl
suggesting a mechanism in the macaque that is less dependent upon electrostatic interactions. SPAG11C, K and L disrupted E. coli membranes but had no effect on erythrocyte membranes. Inhibition of E. coli RNA, DNA and protein synthesis by nonlethal concentrations of SPAG11 isoforms indicated an additional mechanism of bacterial
killing.
Abbreviation: SPAG11, sperm associated antigen 11; CFUs, colony forming units; NPN, N-phenyl-1-napthylamine; diSC3-5, 3,5-dipropylthiadicarbocyanine
iodide; IAA, iodoacetamide; BME, β-mercaptoethanol 相似文献
26.
Solution structure of the plant defensin VrD1 from mung bean and its possible role in insecticidal activity against bruchids 总被引:1,自引:0,他引:1
Vigna radiata plant defensin 1 (VrD1) is the first reported plant defensin exhibiting insecticidal activity. We report herein the nuclear magnetic resonance solution structure of VrD1 and the implication on its insecticidal activity. The root-mean-square deviation values are 0.51 +/- 0.35 and 1.23 +/- 0.29 A for backbone and all heavy atoms, respectively. The VrD1 structure comprises a triple-stranded antiparallel beta-sheet, an alpha-helix, and a 3(10) helix stabilized by four disulfide bonds, forming a typical cysteine-stabilized alphabeta motif. Among plant defensins of known structure, VrD1 is the first to contain a 3(10) helix. Glu26 is highly conserved among defensins; VrD1 contains an arginine at this position, which may induce a shift in the orientation of Trp10, thereby promoting the formation of this 3(10) helix. Moreover, VrD1 inhibits Tenebrio molitor alpha-amylase. Alpha-amylase has an essential role in the digestion of plant starch in the insect gut, and expression of the common bean alpha-amylase inhibitor 1 in transgenic pea imparts complete resistance against bruchids. These results imply that VrD1 insecticidal activity has its basis in the inhibition of a polysaccharide hydrolase. Sequence and structural comparisons between two groups of plant defensins having different specificity toward insect alpha-amylase reveal that the loop between beta2 and beta3 is the probable binding site for the alpha-amylase. Computational docking experiments were used to study VrD1-alpha-amylase interactions, and these results provide information that may be used to improve the insecticidal activity of VrD1. 相似文献
27.
Mirouze M Sels J Richard O Czernic P Loubet S Jacquier A François IE Cammue BP Lebrun M Berthomieu P Marquès L 《The Plant journal : for cell and molecular biology》2006,47(3):329-342
The metal tolerance of metal hyper-accumulating plants is a poorly understood mechanism. In order to unravel the molecular basis of zinc (Zn) tolerance in the Zn hyper-accumulating plant Arabidopsis halleri ssp. halleri, we carried out a functional screening of an A. halleri cDNA library in the yeast Saccharomyces cerevisiae to search for genes conferring Zn tolerance to yeast cells. The screening revealed four A. halleri defensin genes (AhPDFs), which induced Zn but not cadmium (Cd) tolerance in yeast. The expression of AhPDF1.1 under the control of the 35S promoter in A. thaliana made the transgenic plants more tolerant to Zn than wild-type plants, but did not change the tolerance to Cd, copper (Cu), cobalt (Co), iron (Fe) or sodium (Na). Thus, AhPDF1.1 is able to confer Zn tolerance both to yeast and plants. In A. halleri, defensins are constitutively accumulated at a higher level in shoots than in A. thaliana. A. halleri defensin pools are Zn-responsive, both at the mRNA and protein levels. In A. thaliana, some but not all defensin genes are induced by ZnCl2 treatment, and these genes are not induced by NaCl treatment. Defensins, found in a very large number of organisms, are known to be involved in the innate immune system but have never been found to play any role in metal physiology. Our results support the proposition that defensins could be involved in Zn tolerance in A. halleri, and that a role for plant defensins in metal physiology should be considered. 相似文献
28.
Luciano Neves de Medeiros Renata Angeli Carolina G. Sarzedas Ana Paula Valente Eleonora Kurtenbach 《生物化学与生物物理学报:生物膜》2010,1798(2):105-113
Plant defensins are cysteine-rich cationic peptides, components of the innate immune system. The antifungal sensitivity of certain exemplars was correlated to the level of complex glycosphingolipids in the membrane of fungi strains. Psd1 is a 46 amino acid residue defensin isolated from pea seeds which exhibit antifungal activity. Its structure is characterized by the so-called cysteine-stabilized α/β motif linked by three loops as determined by two-dimensional NMR. In the present work we explored the measurement of heteronuclear Nuclear Overhauser Effects, R1 and R2 15N relaxation ratios, and chemical shift to probe the backbone dynamics of Psd1 and its interaction with membrane mimetic systems with phosphatidylcholine (PC) or dodecylphosphocholine (DPC) with glucosylceramide (CMH) isolated from Fusarium solani. The calculated R2 values predicted a slow motion around the highly conserved among Gly12 residue and also in the region of the Turn3 His36-Trp38. The results showed that Psd1 interacts with vesicles of PC or PC:CMH in slightly different forms. The interaction was monitored by chemical shift perturbation and relaxation properties. Using this approach we could map the loops as the binding site of Psd1 with the membrane. The major binding epitope showed conformation exchange properties in the μs-ms timescale supporting the conformation selection as the binding mechanism. Moreover, the peptide corresponding to part of Loop1 (pepLoop1: Gly12 to Ser19) is also able to interact with DPC micelles acquiring a stable structure and in the presence of DPC:CMH the peptide changes to an extended conformation, exhibiting NOE mainly with the carbohydrate and ceramide parts of CMH. 相似文献
29.
Xiangyun Lu Qiaolin Che Yi Lv Meijuan Wang Zekuan Lu Feifei Feng Jingze Liu Haining Yu 《Protein science : a publication of the Protein Society》2010,19(3):392-397
A novel defensin‐like antimicrobial peptide named longicornsin was isolated from the salivary glands of the hard tick, Haemaphysalis longicornis, using a 10‐kDa cut‐off Centriprep filter and reversed‐phase high‐performance liquid chromatography (RP‐HPLC). Its amino acid sequence was determined as DFGCGQGMIFMCQRRCMRLYPGSTGFCRGFRCMCDTHIPLRPPFMVG by Edman degradation. The cDNA encoding longicornsin was cloned by cDNA library screening. The predicted protein from the cDNA sequence was composed of 78 amino acids including a mature longicornsin. It showed similarity with defensin‐like peptides from other ticks by BLAST search. Different from most other tick defensin‐like peptides, longicornsin had a C‐terminal extension. Purified longicornsin exerted potent antimicrobial activities against bacteria and fungi. Interestingly, it even showed strong antimicrobial ability against drug‐resistant microorganisms and Helicobacter pylori. The results of this study indicated that longicornsin is a potential candidate for novel antimicrobial drug design. 相似文献
30.