The solution structure of the amino-terminal domain of human DNA polymerase ε subunit B is homologous to C-domains of AAA+ proteins

DNA polymerases α, δ and ε are large multisubunit complexes that replicate the bulk of the DNA in the eukaryotic cell. In addition to the homologous catalytic subunits, these enzymes possess structurally related B subunits, characterized by a carboxyterminal calcineurin-like and an aminoproximal oligonucleotide/oligosaccharide binding-fold domain. The B subunits also share homology with the exonuclease subunit of archaeal DNA polymerases D. Here, we describe a novel domain specific to the N-terminus of the B subunit of eukaryotic DNA polymerases ε. The N-terminal domain of human DNA polymerases ε (Dpoe2NT) expressed in Escherichia coli was characterized. Circular dichroism studies demonstrated that Dpoe2NT forms a stable, predominantly α-helical structure. The solution structure of Dpoe2NT revealed a domain that consists of a left-handed superhelical bundle. Four helices are arranged in two hairpins and the connecting loops contain short β-strand segments that form a short parallel sheet. DALI searches demonstrated a striking structural similarity of the Dpoe2NT with the α-helical subdomains of ATPase associated with various cellular activity (AAA+) proteins (the C-domain). Like C-domains, Dpoe2NT is rich in charged amino acids. The biased distribution of the charged residues is reflected by a polarization and a considerable dipole moment across the Dpoe2NT. Dpoe2NT represents the first C-domain fold not associated with an AAA+ protein

Prosthetic Valve Candida Endocarditis: A Case Report with 18F-FDG-PET/CT as Part of the Diagnostic Workup

Diagnosis of Candida spp. infective endocarditis (IE) is challenging, and diagnostic delays are common. We describe two patients with Candida spp. prosthetic valve endocarditis (PVE) and 18fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) as a part of diagnostic workup. We also refer to 5 other cases we found from the published literature. These cases highlight that 18F-FDG-PET/CT can improve diagnostic accuracy in prosthetic valve Candida endocarditis

Biotic stress accelerates formation of climate-relevant aerosols in boreal forests

Boreal forests are a major source of climate-relevant biogenic secondary organic aerosols (SOAs) and will be greatly influenced by increasing temperature. Global warming is predicted to not only increase emissions of reactive biogenic volatile organic compounds (BVOCs) from vegetation directly but also induce large-scale insect outbreaks, which significantly increase emissions of reactive BVOCs. Thus, climate change factors could substantially accelerate the formation of biogenic SOAs in the troposphere. In this study, we have combined results from field and laboratory experiments, satellite observations and global-scale modelling in order to evaluate the effects of insect herbivory and large-scale outbreaks on SOA formation and the Earth's climate. Field measurements demonstrated 11-fold and 20-fold increases in monoterpene and sesquiterpene emissions respectively from damaged trees during a pine sawfly (Neodiprion sertifer) outbreak in eastern Finland. Laboratory chamber experiments showed that feeding by pine weevils (Hylobius abietis) increased VOC emissions from Scots pine and Norway spruce seedlings by 10-50 fold, resulting in 200-1000-fold increases in SOA masses formed via ozonolysis. The influence of insect damage on aerosol concentrations in boreal forests was studied with a global chemical transport model GLOMAP and MODIS satellite observations. Global-scale modelling was performed using a 10-fold increase in monoterpene emission rates and assuming 10% of the boreal forest area was experiencing outbreak. Results showed a clear increase in total particulate mass (local max. 480 %) and cloud condensation nuclei concentrations (45 %). Satellite observations indicated a 2-fold increase in aerosol optical depth over western Canada's pine forests in August during a bark beetle outbreak. These results suggest that more frequent insect outbreaks in a warming climate could result in substantial increase in biogenic SOA formation in the boreal zone and, thus, affect both aerosol direct and indirect forcing of climate at regional scales. The effect of insect outbreaks on VOC emissions and SOA formation should be considered in future climate predictions.Peer reviewe

Prosthetic Valve Candida Endocarditis: A Case Report with 18F-FDG-PET/CT as Part of the Diagnostic Workup

Diagnosis of Candida spp. infective endocarditis (IE) is challenging, and diagnostic delays are common. We describe two patients with Candida spp. prosthetic valve endocarditis (PVE) and 18fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) as a part of diagnostic workup. We also refer to 5 other cases we found from the published literature. These cases highlight that 18F-FDG-PET/CT can improve diagnostic accuracy in prosthetic valve Candida endocarditis

Organization of the multifunctional enzyme type 1: interaction between N- and C-terminal domains is required for the hydratase-1/isomerase activity.

Rat peroxisomal multifunctional enzyme type 1 (perMFE-1) is a monomeric protein of beta-oxidation. We have defined five functional domains (A, B, C, D and E) in the perMFE-1 based on comparison of the amino acid sequence with homologous proteins from databases and structural data of the hydratase-1/isomerases (H1/I) and (3 S )-hydroxyacyl-CoA dehydrogenases (HAD). Domain A (residues 1-190) comprises the H1/I fold and catalyses both 2-enoyl-CoA hydratase-1 and Delta(3)-Delta(2)-enoyl-CoA isomerase reactions. Domain B (residues 191-280) links domain A to the (3 S )-dehydrogenase region, which includes both domain C (residues 281-474) and domain D (residues 480-583). Domains C and D carry features of the dinucleotide-binding and the dimerization domains of monofunctional HADs respectively. Domain E (residues 584-722) has sequence similarity to domain D of the perMFE-1, which suggests that it has evolved via partial gene duplication. Experiments with engineered perMFE-1 variants demonstrate that the H1/I competence of domain A requires stabilizing interactions with domains D and E. The variant His-perMFE (residues 288-479)Delta, in which the domain C is deleted, is stable and has hydratase-1 activity. It is proposed that the extreme C-terminal domain E in perMFE-1 serves the following three functions: (i) participation in the folding of the N-terminus into a functionally competent H1/I fold, (ii) stabilization of the dehydrogenation domains by interaction with the domain D and (iii) the targeting of the perMFE-1 to peroxisomes via its C-terminal tripeptide

Interaction between the C-terminal region of human myelin basic protein and calmodulin: analysis of complex formation and solution structure-5

Ion volumes and molecular weights (in kDa) of the standard proteins used to calibrate the column. The positions of the collected fractions from the complex sample are indicated below the graph. The absorbances have been multiplied by 1000 for clarity. B. Electrophoretic analysis of the fractions obtained from the complex sample on a 16.5-% Tris-tricine peptide gel. The samples are as follows: 1, the CaM-peptide mixture injected into the column; 2, fraction 10; 3, fraction 11; 4, fraction 12; 5, CaM; 6, peptide. The positions of molecular weight markers (in kDa) are indicated on the left, and the positions of CaM and the peptide are indicated on right. Note how the peak fraction (lane 3) contains both CaM and the peptide. A weak low-molecular-weight shadow is also seen in the CaM sample (lane 5), but the peptide stains intensely dark with silver and can unequivocally be detected based on its colour. The faint band above CaM is most likely another conformation of CaM.<p><b>Copyright information:</b></p><p>Taken from "Interaction between the C-terminal region of human myelin basic protein and calmodulin: analysis of complex formation and solution structure"</p><p>http://www.biomedcentral.com/1472-6807/8/10</p><p>BMC Structural Biology 2008;8():10-10.</p><p>Published online 19 Feb 2008</p><p>PMCID:PMC2288786.</p><p></p