排序方式: 共有193条查询结果,搜索用时 31 毫秒
161.
Monika Piro Tomasz Maecki Magda Portas Izabela Magierowska Damian Trojanowski David Sherratt Jolanta Zakrzewska‐Czerwiska Katarzyna Ginda Dagmara Jakimowicz 《Molecular microbiology》2019,111(1):204-220
Although mycobacteria are rod shaped and divide by simple binary fission, their cell cycle exhibits unusual features: unequal cell division producing daughter cells that elongate with different velocities, as well as asymmetric chromosome segregation and positioning throughout the cell cycle. As in other bacteria, mycobacterial chromosomes are segregated by pair of proteins, ParA and ParB. ParA is an ATPase that interacts with nucleoprotein ParB complexes – segrosomes and non‐specifically binds the nucleoid. Uniquely in mycobacteria, ParA interacts with a polar protein DivIVA (Wag31), responsible for asymmetric cell elongation, however the biological role of this interaction remained unknown. We hypothesised that this interaction plays a critical role in coordinating chromosome segregation with cell elongation. Using a set of ParA mutants, we determined that disruption of ParA‐DNA binding enhanced the interaction between ParA and DivIVA, indicating a competition between the nucleoid and DivIVA for ParA binding. Having identified the ParA mutation that disrupts its recruitment to DivIVA, we found that it led to inefficient segrosomes separation and increased the cell elongation rate. Our results suggest that ParA modulates DivIVA activity. Thus, we demonstrate that the ParA‐DivIVA interaction facilitates chromosome segregation and modulates cell elongation. 相似文献
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163.
Grégory Baronian Katarzyna Ginda Laurence Berry Martin Cohen-Gonsaud Jolanta Zakrzewska-Czerwińska Dagmara Jakimowicz Virginie Molle 《PloS one》2015,10(3)
Here, we present for the first time that Mycobacterium tuberculosis ParB is phosphorylated by several mycobacterial Ser/Thr protein kinases in vitro. ParB and ParA are the key components of bacterial chromosome segregation apparatus. ParB is a cytosolic conserved protein that binds specifically to centromere-like DNA parS sequences and interacts with ParA, a weak ATPase required for its proper localization. Mass spectrometry identified the presence of ten phosphate groups, thus indicating that ParB is phosphorylated on eight threonines, Thr32, Thr41, Thr53, Thr110, Thr195, and Thr254, Thr300, Thr303 as well as on two serines, Ser5 and Ser239. The phosphorylation sites were further substituted either by alanine to prevent phosphorylation or aspartate to mimic constitutive phosphorylation. Electrophoretic mobility shift assays revealed a drastic inhibition of DNA-binding by ParB phosphomimetic mutant compared to wild type. In addition, bacterial two-hybrid experiments showed a loss of ParA-ParB interaction with the phosphomimetic mutant, indicating that phosphorylation is regulating the recruitment of the partitioning complex. Moreover, fluorescence microscopy experiments performed in the surrogate Mycobacterium smegmatis ΔparB strain revealed that in contrast to wild type Mtb ParB, which formed subpolar foci similar to M. smegmatis ParB, phoshomimetic Mtb ParB was delocalized. Thus, our findings highlight a novel regulatory role of the different isoforms of ParB representing a molecular switch in localization and functioning of partitioning protein in Mycobacterium tuberculosis. 相似文献
164.
Harper J Armstead I Thomas A James C Gasior D Bisaga M Roberts L King I King J 《Annals of botany》2011,107(8):1313-1321
Background and Aims
To address the issues associated with food security, environmental change and bioenergy in the context of crop plants, the production, identification and evaluation of novel plant phenotypes is fundamental. One of the major routes to this end will be wide hybridization and introgression breeding. The transfer of chromosomes and chromosome segments between related species (chromosome engineering or alien introgression) also provides an important resource for determining the genetic control of target traits. However, the realization of the full potential of chromosome engineering has previously been hampered by the inability to identify and characterize interspecific introgressions accurately.Methods
Seven monosomic substitution lines have been generated comprising Festuca pratensis as the donor species and Lolium perenne as the recipient. Each of the seven lines has a different L. perenne chromosome replaced by the homoeologous F. pratensis chromosome (13 L. perenne + 1 F. pratensis chromosome). Molecular markers and genomic in situ hybridization (GISH) were used to assign the F. pratensis chromosomes introgressed in each of the monosomic substitutions to a specific linkage group. Cytological observations were also carried out on metaphase I of meiosis in each of the substitution lines.Results
A significant level of synteny was found at the macro-level between L. perenne and F. pratensis. The observations at metaphase I revealed the presence of a low level of interspecific chromosomal translocations between these species.Discussion
The isolation of the seven monosomic substitution lines provides a resource for dissecting the genetic control of important traits and for gene isolation. Parallels between the L. perenne/F. pratensis system and the Pooideae cereals such as wheat, barley, rye, oats and the model grass Brachypodium distachyon present opportunities for a comparison across the species in terms of genotype and phenotype. 相似文献165.
Anita Hryncewicz-Gwó?d? Tomasz Jagielski Katarzyna Kalinowska Dagmara Baczyńska Ewa Plomer-Niezgoda Jacek Bielecki 《Mycopathologia》2012,174(5-6):383-388
Trichophyton rubrum is the most significant agent of dermatomycoses worldwide, primarily causing tinea pedis and tinea unguium. PCR analysis of tandemly repetitive subelements (TRS) within the rDNA nontranscribed spacer region is a major tool for molecular typing of T. rubrum. The aim of this study was to investigate the stability of TRS PCR patterns by analyzing isogenic strains of T. rubrum. Twenty-seven groups of isogenic T. rubrum strains were examined, each composed of an original clinical isolate and its 3 subcultures, maintained on a drug-free medium, a medium containing fluconazole and itraconazole. TRS typing was performed for the original strains and their subcultures grown after 12 passages, at 4-week intervals, on respective media. To add more objectivity to the results, TRS typing for each of the isogenic strain was performed three times, using DNA isolated from three different colonies. Among 27 groups of isogenic strains, all but one were exclusively composed of strains with identical TRS-1 and TRS-2 PCR patterns. In one group, 3 isolates from the last, twelfth passage had identical TRS-1 PCR profiles (type 1), yet different TRS-2 PCR profiles, as compared with the original strain (type I vs. type II). The mechanism underlying the genotype switch was a deletion of a single repeat unit in the TRS-2 locus, as evidenced by sequence analysis. In the interpretation of TRS typing results, microevolutionary events need to be taken into account, urging drawing epidemiological conclusions with caution and in conjunction with other genotyping data and traditional contact tracing information. 相似文献
166.
Chattopadhyay S Tchesnokova V McVeigh A Kisiela DI Dori K Navarro A Sokurenko EV Savarino SJ 《The Journal of biological chemistry》2012,287(9):6150-6158
Class 5 fimbriae of enterotoxigenic Escherichia coli (ETEC) comprise eight serologically discrete colonization factors that mediate small intestinal adhesion. Their differentiation has been attributed to the pressure imposed by host adaptive immunity. We sequenced the major pilin and minor adhesin subunit genes of a geographically diverse population of ETEC elaborating CFA/I (n = 31), CS17 (n = 20), and CS2 (n = 18) and elucidated the functional effect of microevolutionary processes. Between the fimbrial types, the pairwise nucleotide diversity for the pilin or adhesin genes ranged from 35-43%. Within each fimbrial type, there were 17 non-synonymous and 1 synonymous point mutations among all pilin or adhesin gene copies, implying that each fimbrial type was acquired by ETEC strains very recently, consistent with a recent origin of this E. coli pathotype. The 17 non-synonymous allelic differences occurred in the CFA/I pilin gene cfaB (two changes) and adhesin gene cfaE (three changes), and CS17 adhesin gene csbD (12 changes). All but one amino acid change in the adhesins clustered around the predicted ligand-binding pocket. Functionally, these changes conferred an increase in cell adhesion in a flow chamber assay. In contrast, the two mutations in the non-adhesive CfaB subunit localized to the intersubunit interface and significantly reduced fimbrial adhesion in this assay. In conclusion, naturally occurring mutations in the ETEC adhesive and non-adhesive subunits altered function, were acquired under positive selection, and are predicted to impact bacteria-host interactions. 相似文献
167.
Streptomycetes are antibiotic-producing filamentous microorganisms that have a mycelial life style. In many ways streptomycetes are the odd ones out in terms of cell division. While the basic components of the cell division machinery are similar to those found in rod-shaped bacteria such as Escherichia coli and Bacillus subtilis, many aspects of the control of cell division and its co-ordination with chromosome segregation are remarkably different. The rather astonishing fact that cell division is not essential for growth makes these bacteria unique. The fundamental difference between the cross-walls produced during normal growth and sporulation septa formed in aerial hyphae, and the role of the divisome in their formation are discussed. We then take a closer look at the way septum site localization is regulated in the long and multinucleoid Streptomyces hyphae, with particular focus on actinomycete-specific proteins and the role of nucleoid segregation and condensation. 相似文献
168.
A Radwanska M Litwin D Nowak D Baczynska Y Wegrowski FX Maquart M Malicka-Blaszkiewicz 《Experimental cell research》2012,318(18):2312-2323
Cell migration is a multistep process initiated by extracellular matrix components that leads to cytoskeletal changes and formation of different protrusive structures at the cell periphery. Lumican, a small extracellular matrix leucine-rich proteoglycan, has been shown to inhibit human melanoma cell migration by binding to α2β1 integrin and affecting actin cytoskeleton organization. The aim of this study was to determine the effect of lumican overexpression on the migration ability of human colon adenocarcinoma LS180 cells. The cells stably transfected with plasmid containing lumican cDNA were characterized by the increased chemotactic migration measured on Transwell filters. Lumican-overexpressing cells presented the elevated filamentous to monomeric actin ratio and gelsolin up-regulation. This was accompanied by a distinct cytoskeletal actin rearrangement and gelsolin subcellular relocation, as observed under laser scaning confocal microscope. Moreover, LS180 cells overexpressing lumican tend to form podosome-like structures as indicated by vinculin redistribution and its colocalization with gelsolin and actin at the submembrane region of the cells. In conclusion, the elevated level of lumican secretion to extracellular space leads to actin cytoskeletal remodeling followed by an increase in migration capacity of human colon LS180 cells. These data suggest that lumican expression and its presence in ECM has an impact on colon cancer cells motility and may modulate invasiveness of colon cancer. 相似文献
169.
Measurement of hematological and serum biochemical normal values of captive housed Chlorocebus aethiops sabaeus monkeys and correlation with the age
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170.
Synthesis,binding affinities and metabolic stability of dimeric dermorphin analogs modified with β3‐homo‐amino acids
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Oliwia Frączak Anika Lasota Dagmara Tymecka Piotr Kosson Adriana Muchowska Aleksandra Misicka Aleksandra Olma 《Journal of peptide science》2016,22(4):222-227
In this study, proteinogenic amino acids residues of dimeric dermorphin pentapeptides were replaced by the corresponding β3‐homo‐amino acids. The potency and selectivity of hybrid α/β dimeric dermorphin pentapeptides were evaluated by competetive receptor binding assay in the rat brain using [3H]DAMGO (a μ ligand) and [3H]DELT (a δ ligand). Tha analog containing β3‐homo‐Tyr in place of Tyr (Tyr‐d ‐Ala‐Phe‐Gly‐β3‐homo‐Tyr‐NH‐)2 showed good μ receptor affinity and selectivity (IC50 = 0.302, IC50 ratio μ/δ = 68) and enzymatic stability in human plasma. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. 相似文献