Structural and temporal regulation of centromeric chromatinThis paper is one of a selection of papers published in this Special Issue, entitled 29th Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2009 ◽  
Vol 87 (1) ◽  
pp. 255-264 ◽  
Author(s):  
Barbara G. Mellone

Normal inheritance of genetic material requires that chromosomes segregate faithfully during mitosis and meiosis. The kinetochore is a unique structure that attaches chromosomes to the microtubule spindle, monitors proper chromosome attachment to the spindle through the mitotic checkpoint, and couples spindle and motor protein forces to move chromosomes during prometaphase and anaphase. The centromere is a specialized chromosomal site that is the structural and functional foundation for kinetochore formation, and is characterized by a unique type of chromatin that needs to be reconstituted after each replication cycle. In this review, recent progress in understanding the structural nature of this chromatin and how it is specifically maintained through cell division are discussed.

2006 ◽  
Vol 84 (4) ◽  
pp. 505-507 ◽  
Author(s):  
Emily Bernstein ◽  
Sandra B. Hake

Changes in the overall structure of chromatin are essential for the proper regulation of cellular processes, including gene activation and silencing, DNA repair, chromosome segregation during mitosis and meiosis, X chromosome inactivation in female mammals, and chromatin compaction during apoptosis. Such alterations of the chromatin template occur through at least 3 interrelated mechanisms: post-translational modifications of histones, ATP-dependent chromatin remodeling, and the incorporation (or replacement) of specialized histone variants into chromatin. Of these mechanisms, the exchange of variants into and out of chromatin is the least well understood. However, the exchange of conventional histones for variant histones has distinct and profound consequences within the cell. This review focuses on the growing number of mammalian histone variants, their particular biological functions and unique features, and how they may affect the structure of the nucleosome. We propose that a given nucleosome might not consist of heterotypic variants, but rather, that only specific histone variants come together to form a homotypic nucleosome, a hypothesis that we refer to as the nucleosome code. Such nucleosomes might in turn participate in marking specific chromatin domains that may contribute to epigenetic inheritance.


2007 ◽  
Vol 85 (2) ◽  
pp. 203-208 ◽  
Author(s):  
Hongmei Dong ◽  
Xiaohu Xu ◽  
Mohong Deng ◽  
Xiaojun Yu ◽  
Hu Zhao ◽  
...  

The aim of the study was to prepare an active recombinant human perforin by comparing 5 candidate segments of human perforin. Full-length perforin, MAC1 (28–349 aa), MAC2 (166–369 aa), C-100, and N-60 of human perforin were selected as candidate active segments and designated, respectively, HP1, HP2, HP3, HP4, and HP5. The target genes were amplified by PCR and the products were individually subcloned into pGEM-T. The genes for HP1, HP2, HP3, and HP5 were subcloned into pET-DsbA, whereas pET-41a (+) was used as the expression vector of HP4. The fusion proteins were expressed in Escherichia coli BL21pLysS(DE3) and purified using nickel nitrilotriacetic acid (NTA) agarose affinity chromatography. The hemolysis microassay was used as an activity assay of fusion protein. From this study, we obtained the recombinant plasmids pGEM-T-HP1, -HP2, -HP3, -HP4 and -HP5, consisting of 1600, 960, 600, 300bp, and 180, respectively. From these recombinant plasmids, expression plasmids were successfully constructed and expressed in E. coli BL21pLysS(DE3). The resultant fusion proteins, affinity purified using Ni–NTA, were ~80, 58, 45, 44, and 30 kDa, respectively. The recombinant proteins were assayed for activity on hemolysis. HP2 and HP5 were the only recombinant proteins that were active in hemolysis, and the hemolytic function was concentration dependent. These results demonstrate that active recombinant forms of perforin can be synthesized in a prokaryote model. The recombinant N-60 and MAC1 (28–349 aa) of human perforin have the function of forming pores. Our study provides the experimental basis for further investigation on the application of perforin.


2020 ◽  
Vol 10 (2) ◽  
pp. 92
Author(s):  
Rosmaina Rosmaina ◽  
Dedi Mulyadi ◽  
Rita Elfianis ◽  
Zulfahmi Zulfahmi

Chili is an important horticultural plant in Indonesia. This research aims to carry out RAPD analysis on Mutant M2 of chili pepper (Capsicum annuum L.). Six M2 genotypes of chili irradiated by gamma ray and control plants were amplified by 16 random primers. The amplification results of M2 chili with 16 primers produced 118 loci, with fragment sizes ranging from 150-2000 bp. The number of polymorphic loci was 96 loci and the percentage of polymorphic loci was 83.23%. The DNA fragment polymorphism produced in this research was relatively high and it showed that the gamma ray mutagen applied produced high chili genetic diversity. The value of genetic similarity between control plants and mutant plants ranged from 0.7474 to 0.4874. UPGMA dendogram classified seven genotypes tested into three groups, the first group consisted of mutants R2U6 and R2U17, the second group was mutants R1U14 and R1U17, and the third group was mutants R2U8, mutants R2U2 and control plants. The finding of this research can be used as a basic selection of genetic material for chili’s breeding in the future.


1999 ◽  
Vol 181 (23) ◽  
pp. 7291-7297 ◽  
Author(s):  
Anne Breüner ◽  
Lone Brøndsted ◽  
Karin Hammer

ABSTRACT In this work, the phage-encoded proteins involved in site-specific excision of the prophage genome of the temperate lactococcal bacteriophage TP901-1 were identified. The phage integrase is required for the process, and a low but significant frequency of excision is observed when the integrase is the only phage protein present. However, 100% excision is observed when the phage protein Orf7 is provided as well as the integrase. Thus, Orf7 is the TP901-1 excisionase, and it is the first excisionase identified that is used during excisive recombination catalyzed by an integrase belonging to the family of extended resolvases. Orf7 is a basic protein of 64 amino acids, and the corresponding gene (orf7) is the third gene in the early lytic operon. This location of an excisionase gene of a temperate bacteriophage has never been described before. The experiments are based on in vivo excision of specifically designed excision vectors carrying the TP901-1 attP site which are integrated intoattB on the chromosome of Lactococcus lactis. Excision of the vectors was investigated in the presence of different TP901-1 genes. In order to detect very low frequencies of excision, a method for positive selection of loss of genetic material based upon the upp gene (encoding uracil phosphoribosyltransferase) was designed, since upp mutants are resistant to fluorouracil. By using this system, frequencies of excision on the order of 10−5 per cell could easily be measured. The described selection principle may be of general use for many organisms and also for types of deletion events other than excision.


2006 ◽  
Vol 84 (3) ◽  
pp. 282-290 ◽  
Author(s):  
Dominique Legrand ◽  
Elisabeth Elass ◽  
Mathieu Carpentier ◽  
Joël Mazurier

The antimicrobial activities of lactoferrin (Lf) depend on its capacity to bind iron and on its direct interaction with the surface of microorganisms. Its protective effect also extends to the regulation of the host response to infections. Depending on the immune status of an individual, Lf can have anti-inflammatory properties that downregulate the immune response and prevent septic shock and damage to tissues. It also acts as a promoter of the activation, differentiation, and (or) proliferation of immune cells. Although most of the anti-inflammatory activities are correlated with the neutralization of proinflammatory molecules by Lf, the promoting activity seems to be related to a direct effect of Lf on immune cells. Although the mechanisms that govern these activities are not clearly defined, and probably differ from cell to cell, several cellular targets and possible mechanisms of action are highlighted. The majority of the molecular targets at the surface of cells are multiligand receptors but, interestingly, most of them have been reported as signaling, endocytosis, and nuclear-targeting molecules. This review focuses on the known and putative mechanisms that allow the immunoregulating effect of Lf in its interactions with immune cells.


2010 ◽  
Vol 88 (2) ◽  
pp. 269-290 ◽  
Author(s):  
Sarah Rauscher ◽  
Régis Pomès

Protein disorder is abundant in proteomes throughout all kingdoms of life and serves many biologically important roles. Disordered states of proteins are challenging to study experimentally due to their structural heterogeneity and tendency to aggregate. Computer simulations, which are not impeded by these properties, have recently emerged as a useful tool to characterize the conformational ensembles of intrinsically disordered proteins. In this review, we provide a survey of computational studies of protein disorder with an emphasis on the interdisciplinary nature of these studies. The application of simulation techniques to the study of disordered states is described in the context of experimental and bioinformatics approaches. Experimental data can be incorporated into simulations, and simulations can provide predictions for experiment. In this way, simulations have been integrated into the existing methodologies for the study of disordered state ensembles. We provide recent examples of simulations of disordered states from the literature and our own work. Throughout the review, we emphasize important predictions and biophysical understanding made possible through the use of simulations. This review is intended as both an overview and a guide for structural biologists and theoretical biophysicists seeking accurate, atomic-level descriptions of disordered state ensembles.


2010 ◽  
Vol 6 (3) ◽  
pp. 251-258 ◽  
Author(s):  
M. Simsek ◽  
A.B. Kuden

2020 ◽  
Vol 17 ◽  
pp. 00125
Author(s):  
Vladimir Molianov ◽  
Oleg Vinogradov ◽  
Natalya Ivanayskaya

In the modern changing climate, selective breeding has been essential for increasing production and ensuring stable yields. Potato varieties with different ripening periods are suitable for the conditions of the Middle Volga region. High-yielding varieties resistant to mechanical damage and diseases, varieties with increased heat resistance and a complex of other important features are being created. The emergence of new directions has complicated the solution of breeding programs and required the orgaization of an intermediate stage in this work: the identification and use of special parent forms - carriers of useful qualities. This is a basic, but necessary task when involving a variety of genetic material in the selection process. Research on the topic was carried out in 2017–2019 in the Samara region (RF) in a special shielded area of AGROSTAR LLC in cooperation with experts of the potato farm of VNIIKH FGBNU, MAG LLC (Kinel), Agrocenter Korenevo LLC, and with the participation of experts of Bavaria-Saat GmbH, Germany.


2011 ◽  
Vol 89 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Tamara L. Caterino ◽  
Jeffrey J. Hayes

Linker histones are multifunctional proteins that are involved in a myriad of processes ranging from stabilizing the folding and condensation of chromatin to playing a direct role in regulating gene expression. However, how this class of enigmatic proteins binds in chromatin and accomplishes these functions remains unclear. Here we review data regarding the H1 structure and function in chromatin, with special emphasis on the C-terminal domain (CTD), which typically encompasses approximately half of the mass of the linker histone and includes a large excess of positively charged residues. Owing to its amino acid composition, the CTD was previously proposed to function in chromatin as an unstructured polycation. However, structural studies have shown that the CTD adopts detectable secondary structure when interacting with DNA and macromolecular crowding agents. We describe classic and recent experiments defining the function of this domain in chromatin folding and emerging data indicating that the function of this protein may be linked to intrinsic disorder.


2010 ◽  
Vol 88 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Caroline A. Ewens ◽  
Patrik Kloppsteck ◽  
Andreas Förster ◽  
Xiaodong Zhang ◽  
Paul S. Freemont

p97, also known as VCP (valosin-containing protein), is a hexameric AAA+ ATPase that participates in a variety of cellular processes. It is believed that p97 mediates these processes through the binding of various adaptor proteins. Many factors govern adaptor binding and the regulatory mechanisms are not yet well understood. Sites of phosphorylation and acetylation on p97 have been identified and such post-translational modifications may be involved in regulating p97 function. Phosphorylation and, to a lesser extent, acetylation of p97 have been shown to modify its properties — for example, by modulating adaptor binding and directing subcellular localization. These modifications have been implicated in a number of p97-mediated processes, including misfolded protein degradation, membrane fusion, and transcription factor activation. This review describes the known phosphorylation and acetylation sites on p97 and discusses their possible structural and functional implications.


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