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Mutations at residues 282, 286, and 293 of phage lambda integrase exert pathway-specific effects on synapsis and catalysis in recombination 下载免费PDF全文
Bankhead TM Etzel BJ Wolven F Bordenave S Boldt JL Larsen TA Segall AM 《Journal of bacteriology》2003,185(8):2653-2666
Bacteriophage lambda integrase (Int) catalyzes site-specific recombination between pairs of attachment (att) sites. The att sites contain weak Int-binding sites called core-type sites that are separated by a 7-bp overlap region, where cleavage and strand exchange occur. We have characterized a number of mutant Int proteins with substitutions at positions S282 (S282A, S282F, and S282T), S286 (S286A, S286L, and S286T), and R293 (R293E, R293K, and R293Q). We investigated the core- and arm-binding properties and cooperativity of the mutant proteins, their ability to catalyze cleavage, and their ability to form and resolve Holliday junctions. Our kinetic analyses have identified synapsis as the rate-limiting step in excisive recombination. The IntS282 and IntS286 mutants show defects in synapsis in the bent-L and excisive pathways, respectively, while the IntR293 mutants exhibit synapsis defects in both the excision and bent-L pathways. The results of our study support earlier findings that the catalytic domain also serves a role in binding to core-type sites, that the core contacts made by this domain are important for both synapsis and catalysis, and that Int contacts core-type sites differently among the four recombination pathways. We speculate that these residues are important for the proper positioning of the catalytic residues involved in the recombination reaction and that their positions differ in the distinct nucleoprotein architectures formed during each pathway. Finally, we found that not all catalytic events in excision follow synapsis: the attL site probably undergoes several rounds of cleavage and ligation before it synapses and exchanges DNA with attR. 相似文献
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Palmitoylation of p59fyn is reversible and sufficient for plasma membrane association. 总被引:6,自引:1,他引:5 下载免费PDF全文
Members of the Src family of protein tyrosine kinases are localized to subspecialized regions of the plasma membrane. Herein we show that the N-terminal SH4 region of the Src family member p59fyn (Fyn) is both necessary and sufficient for targeting of Fyn and heterologous proteins to the plasma membrane and detergent-insoluble subdomains. Attachment of the first 16 amino acids of Fyn to a normally cytosolic protein, beta-galactosidase, resulted in distinct plasma membrane localization of the chimeric protein. Mutation of the palmitoylation site (cysteine-3) within Fyn16-beta-galactosidase or wild-type Fyn abrogated plasma membrane localization, resulting in redistribution of the mutant proteins into intracellular membranes. Substitution of the SH4 motif within Fyn with heterologous sequences from other palmitoylated proteins (G alpha o and GAP43) revealed that the presence of palmitate is sufficient to direct plasma membrane localization independent of surrounding amino acid sequences and myristate. Palmitoylated Fyn chimeras were also enriched in the Triton X-100-resistant matrix, whereas nonpalmitoylated forms of these proteins were detected in the detergent-soluble fraction. The palmitate moiety on Fyn exhibited a half-life of 1.5-2 h. In contrast, the half-life of the polypeptide backbone was 8 h, indicating that palmitoylation is a reversible modification. These studies establish that the palmitoylated SH4 sequence of Fyn can be used to specifically target proteins to the plasma membrane in a reversible manner. 相似文献
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Shi Yu Tillmann Falck Anneleen Daemen Leon-Charles Tranchevent Johan AK Suykens Bart De Moor Yves Moreau 《BMC bioinformatics》2010,11(1):309
Background
This paper introduces the notion of optimizing different norms in the dual problem of support vector machines with multiple kernels. The selection of norms yields different extensions of multiple kernel learning (MKL) such as L ∞, L 1, and L 2 MKL. In particular, L 2 MKL is a novel method that leads to non-sparse optimal kernel coefficients, which is different from the sparse kernel coefficients optimized by the existing L ∞ MKL method. In real biomedical applications, L 2 MKL may have more advantages over sparse integration method for thoroughly combining complementary information in heterogeneous data sources. 相似文献6.
The Indian black berry (Syzygium cumini Skeels) has a great nutraceutical and medicinal properties. As in other fruit crops, the
fruit characteristics are important attributes for differentiation were also determined for different accessions of S. cumini. The fruit
weight, length, breadth, length: breadth ratio, pulp weight, pulp content, seed weight and pulp: seed ratio significantly varied in
different accessions. Molecular characterization was carried out using PCR based RAPD technique. Out of 80 RAPD primers, only
18 primers produced stable polymorphisms that were used to examine the phylogenetic relationship. A sum of 207 loci were
generated out of which 201 loci found polymorphic. The average genetic dissimilarity was 97 per cent among jamun accessions.
The phylogenetic relationship was also determined by principal coordinates analysis (PCoA) that explained 46.95 per cent
cumulative variance. The two-dimensional PCoA analysis showed grouping of the different accessions that were plotted into four
sub-plots, representing clustering of accessions. The UPGMA (r = 0.967) and NJ (r = 0.987) dendrogram constructed based on the
dissimilarity matrix revealed a good degree of fit with the cophenetic correlation value. The dendrogram grouped the accessions
into three main clusters according to their eco-geographical regions which given useful insight into their phylogenetic
relationships. 相似文献
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不同耕作措施对冬小麦-夏玉米复种连作系统土壤有机碳和水分利用效率的影响 总被引:2,自引:1,他引:1
在连续8年田间定位试验的基础上,分析了关中平原冬小麦 夏玉米复种连作系统2008—2009年连续两个生长季期间不同耕作措施(结合秸秆还田和不还田)对土壤有机碳和水分利用率的影响.结果表明: 相对于传统耕作,保护性耕作有利于土壤有机碳、水分利用效率和作物产量的提高,其中在“深松+秸秆还田”耕作模式下的增幅最高,土壤有机碳含量在0~30 cm土层增幅达到19.5%,水分利用效率和作物产量提高了16.9%和20.5%,而免耕模式则有效提高了0~10 cm土层有机碳含量.在该地区土壤和气候条件下,深松结合秸秆粉碎还田是最理想的耕作模式,最有利于土壤有机碳累积,并提高水分利用效率和作物产量. 相似文献
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K Michałek M Laszczyńska AK Ciechanowicz A Herosimczyk I Rotter M Oganowska 《Biotechnic & histochemistry》2014,89(5):342-347
Aquaporin 2 (AQP2) is a small, integral tetrameric plasma membrane protein that is expressed in mammalian kidneys. The specific constitution of this protein and its selective permeability to water means that AQP2 plays an important role in hypertonic urine production. Immunolocalization of AQP2 has been studied in humans, monkeys, sheep, dogs, rabbits, rats, mice and adult cattle. We analyzed the expression of AQP2 in kidneys of 7-month-old Polish-Friesian var. black and white male calves. AQP2 was localized in the principal cells of collecting ducts in medullary rays penetrating the renal cortex and in the collecting ducts of renal medulla. AQP2 was expressed most strongly in the apical plasma membrane, but expression was observed also in the intracellular vesicles and basolateral plasma membrane. Our study provides new information concerning the immunolocalization of AQP2 in calf kidneys. 相似文献
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The sequences of the 5' long-terminal repeat (LTR) and adjacent leader
regions of 27 full-length copia elements isolated from natural populations
of Drosophila melanogaster, D. simulans, and D. mauritiana are presented.
Phylogenetic analyses indicate that although D. melanogaster copia elements
are distinct from those of D. simulans and D. mauritiana, the elements of
these latter two species are not distinguishable from one another. LTRs and
adjacent 5' leader regions of elements isolated from D. simulans and D.
mauritiana are structurally similar to one another and carry substantial
deletional variation mapping to regions previously identified as being of
potential importance for copia expression.
相似文献