The DEK protein--an abundant and ubiquitous constituent of mammalian chromatin

The protein DEK is an abundant and ubiquitous chromatin protein in multicellular organisms (not in yeast). It is expressed in more than a million copies/nucleus of rapidly proliferating mammalian cells. DEK has two DNA binding modules of which one includes a SAP box, a sequence motif that DEK shares with a number of other chromatin proteins. DEK has no apparent affinity to specific DNA sequences, but preferentially binds to superhelical and cruciform DNA, and induces positive supercoils into closed circular DNA. The available evidence strongly suggests that DEK could function as an architectural protein in chromatin comparable to the better known classic architectural chromatin proteins, the high-mobility group or HMG proteins.     

Attachment style in parents of children with chronic gastrointestinal disease

Attachment is a point of interest in psychosomatic research since it influences a wide array of biopsychosocial phenomena. Data from literature highlights the role of this concept in the context of Inflammatory Bowel disease (IBD), still, there is a lack of data regarding attachment among parents of children with chronic gastrointestinal diseases. The main hypothesis for the current study is that parents of children with IBD will have a more insecure attachment than parents of children with celiac disease (CD) and parents of healthy children. The second hypothesis is that insecure attachment among parents of sick children will be associated with lower parental quality of life (QoL). 46 parents of children with IBD, 42 parents of children with CD and 43 parents of healthy children completed the validated modification of the Brennan's Experiences in Close Relationship Inventory. Results were categorized as secure and insecure attachment. In order to assess parental QoL, the WHOQOL-BREF questionnaire was used. The Total QoL was calculated as a sum of all domain items. Secure attachment was found in 45.7% parents of children with IBD, in 35.7% parents of children with CD and in 32.6% parents of healthy children. Surprisingly, the lowest rate of secure attachment was found in parents of healthy children. However, significant differences among groups do not exist. For all groups of parents the attachment style is associated with Total QoL, although only among parents of children with IBD, the secure attachment independently and significantly predicts higher parental Total QoL. According to results, we might say that parental attachment style does not have a role that exclusively belongs in the context of paediatric chronic gastrointestinal diseases. However, parents of children with IBD who have insecure attachment represent target group for psychosocial support in order to improve their QoL.     

ArchbotLit—the archaeobotanical literature database: an update of the search engine for literature on archaeological remains of cultivated plants since 1981

Vegetation History and Archaeobotany - The online Archaeobotanical Literature Database (ArchbotLit) is an important tool for getting targeted access to archaeobotanical publications. It offers the...     

Functional domains of the ubiquitous chromatin protein DEK

DEK was originally described as a proto-oncogene protein and is now known to be a major component of metazoan chromatin. DEK is able to modify the structure of DNA by introducing supercoils. In order to find interaction partners and functional domains of DEK, we performed yeast two-hybrid screens and mutational analyses. Two-hybrid screening yielded C-terminal fragments of DEK, suggesting that DEK is able to multimerize. We could localize the domain to amino acids 270 to 350 and show that multimerization is dependent on phosphorylation by CK2 kinase in vitro. We also found two DNA binding domains of DEK, one on a fragment including amino acids 87 to 187 and containing the SAF-box DNA binding motif, which is located between amino acids 149 and 187. This region is sufficient to introduce supercoils into DNA. The second DNA binding domain is located between amino acids 270 and 350 and thus overlaps the multimerization domain. We show that the two DNA-interacting domains differ in their binding properties and in their abilities to respond to CK2 phosphorylation.     

Identification of Pseudomonas syringae type III effectors that can suppress programmed cell death in plants and yeast

The Pseudomonas syringae pv. tomato DC3000 type III secretion system (TTSS) is required for bacterial pathogenicity on plants and elicitation of the hypersensitive response (HR), a programmed cell death (PCD) that occurs on resistant plants. Cosmid pHIR11 enables non-pathogens to elicit an HR dependent upon the TTSS and the effector HopPsyA. We used pHIR11 to determine that effectors HopPtoE, avirulence AvrPphEPto, AvrPpiB1Pto, AvrPtoB, and HopPtoF could suppress a HopPsyA-dependent HR on tobacco and Arabidopsis. Mixed inoculum and Agrobacterium-mediated transient expression experiments confirmed that suppressor action occurred within plant cells. These suppressors, with the exception of AvrPpiB1Pto, inhibited the expression of the tobacco pathogenesis-related (PR) gene PR1a. DC3000 suppressor mutants elicited an enhanced HR consistent with these mutants lacking an HR suppressor. Additionally, HopPtoG was identified as a suppressor on the basis of an enhanced HR produced by a hopPtoG mutant. Remarkably, these proteins functioned to inhibit the ability of the pro-apoptotic protein, Bax to induce PCD in plants and yeast, indicating that these effectors function as anti-PCD proteins in a trans-kingdom manner. The high proportion of effectors that suppress PCD suggests that suppressing plant immunity is one of the primary roles for DC3000 effectors and a central requirement for P. syringae pathogenesis.     

MprF-mediated biosynthesis of lysylphosphatidylglycerol, an important determinant in staphylococcal defensin resistance

Frequently bacteria are exposed to membrane-damaging cationic antimicrobial molecules (CAMs) produced by the host's immune system (defensins, cathelicidins) or by competing microorganisms (bacteriocins). Staphylococcus aureus achieves CAM resistance by modifying anionic phosphatidylglycerol with positively charged L-lysine, resulting in repulsion of the peptides. Inactivation of the novel S. aureus gene, mprF, which is found in many bacterial pathogens, has resulted in the loss of lysylphosphatidylglycerol (L-PG), increased inactivation by CAM-containing neutrophils, and attenuated virulence. We demonstrate here that expression of mprF is sufficient to confer L-PG production in Escherichia coli, which indicates that MprF represents the L-PG synthase. L-PG biosynthesis was studied in vitro and found to be dependent on phosphatidylglycerol and lysyl-tRNA, two putative substrate molecules. Further addition of cadaverin, a competitive inhibitor of the lysyl-tRNA synthetases, or of RNase A abolished L-PG biosynthesis, thereby confirming the involvement of lysyl-tRNA. This study forms the basis for further detailed analyses of L-PG biosynthesis and its role in bacterial infections.     

Genes coding for hepatotoxic heptapeptides (microcystins) in the cyanobacterium Anabaena strain 90

The cluster of microcystin synthetase genes from Anabaena strain 90 was sequenced and characterized. The total size of the region is 55.4 kb, and the genes are organized in three putative operons. The first operon (mcyA-mcyB-mcyC) is transcribed in the opposite direction from the second operon (mcyG-mcyD-mcyJ-mcyE-mcyF-mcyI) and the third operon (mcyH). The genes mcyA, mcyB, and mcyC encode nonribosomal peptide synthetases (NRPS), while mcyD codes for a polyketide synthase (PKS), and mcyG and mcyE are mixed NRPS-PKS genes. The genes mcyJ, mcyF, and mcyI are similar to genes coding for a methyltransferase, an aspartate racemase, and a D-3-phosphoglycerate dehydrogenase, respectively. The region in the first module of mcyB coding for the adenylation domain was found to be 96% identical with the corresponding part of mcyC, suggesting a recent duplication of this fragment and a replacement in mcyB. In Anabaena strain 90, the order of the domains encoded by the genes in the two sets (from mcyG to mcyI and from mcyA to mcyC) is colinear with the hypothetical order of the enzymatic reactions for microcystin biosynthesis. The order of the microcystin synthetase genes in Anabaena strain 90 differs from the arrangement found in two other cyanobacterial species, Microcystis aeruginosa and Planktothrix agardhii. The average sequence match between the microcystin synthetase genes of Anabaena strain 90 and the corresponding genes of the other species is 74%. The identity of the individual proteins varies from 67 to 81%. The genes of microcystin biosynthesis from three major producers of this toxin are now known. This makes it possible to design probes and primers to identify the toxin producers in the environment.     

Localization and functional analysis of PepI, the immunity peptide of Pep5-producing Staphylococcus epidermidis strain 5

Pep5 is a cationic pore-forming lantibiotic produced by Staphylococcus epidermidis strain 5. The producer strain protects itself from the lethal action of its own bacteriocin through the 69-amino-acid immunity peptide PepI. The N-terminal segment of PepI contains a 20-amino-acid stretch of apolar residues, whereas the C terminus is very hydrophilic, with a net positive charge. We used green fluorescent protein (GFP)-PepI fusions to obtain information on its localization in vivo. PepI was found to occur outside the cytoplasm and to accumulate at the membrane-cell wall interface. The extracellular localization appeared essential for conferring immunity. We analyzed the functional role of the specific segments by constructing various mutant peptides, which were also fused to GFP. When the hydrophobic N-terminal segment of PepI was disrupted by introducing charged amino acids, the export of PepI was blocked and clones expressing such mutant peptides were Pep5 sensitive. When PepI was successively shortened at the C terminus, in contrast, its export properties remained unchanged whereas its ability to confer immunity was gradually reduced. The results show that the N-terminal part is required for the transport of PepI and that the C-terminal part is important for conferring the immunity phenotype. A concept based on target shielding is proposed for the PepI immunity mechanism.