Sequential and structural homology between intracellular pathogenesis-related proteins and a group of latex proteins

The intracellular pathogenesis-related proteins have been identified in a broad range of flowering plants. Some display quite different patterns of expression, in many cases unrelated to the pathogenic response. Nevertheless, these proteins are all very similar and in most cases share more than 35% sequence identity. In this report we investigate the significance of a rather weak similarity between the intracellular pathogenesis-related (IPR or PR-10) proteins and a group of proteins identified in the latex of opium poppy and in Arabidopsis, among others. A sequence analysis held together with the recently published three-dimensional structure of Bet v 1, an IPR protein from birch pollen, strongly suggests sequential and structural homology between the two protein families.     

Control of directionality in the DNA strand-exchange reaction catalysed by the tyrosine recombinase TnpI

In DNA site-specific recombination catalysed by tyrosine recombinases, two pairs of DNA strands are sequentially exchanged between separate duplexes and the mechanisms that confer directionality to this theoretically reversible reaction remain unclear. The tyrosine recombinase TnpI acts at the internal resolution site (IRS) of the transposon Tn4430 to resolve intermolecular transposition products. Recombination is catalysed at the IRS core sites (IR1–IR2) and is regulated by adjacent TnpI-binding motifs (DR1 and DR2). These are dispensable accessory sequences that confer resolution selectivity to the reaction by stimulating synapsis between directly repeated IRSs. Here, we show that formation of the DR1–DR2-containing synapse imposes a specific order of activation of the TnpI catalytic subunits in the complex so that the IR1-bound subunits catalyse the first strand exchange and the IR2-bound subunits the second strand exchange. This ordered pathway was demonstrated for a complete recombination reaction using a TnpI catalytic mutant (TnpI-H234L) partially defective in DNA rejoining. The presence of the DR1- and DR2-bound TnpI subunits was also found to stabilize transient recombination intermediates, further displacing the reaction equilibrium towards product formation. Implication of TnpI/IRS accessory elements in the initial architecture of the synapse and subsequent conformational changes taking place during strand exchange is discussed.     

Crystal Structures of DNA-Whirly Complexes and Their Role in Arabidopsis Organelle Genome Repair

DNA double-strand breaks are highly detrimental to all organisms and need to be quickly and accurately repaired. Although several proteins are known to maintain plastid and mitochondrial genome stability in plants, little is known about the mechanisms of DNA repair in these organelles and the roles of specific proteins. Here, using ciprofloxacin as a DNA damaging agent specific to the organelles, we show that plastids and mitochondria can repair DNA double-strand breaks through an error-prone pathway similar to the microhomology-mediated break-induced replication observed in humans, yeast, and bacteria. This pathway is negatively regulated by the single-stranded DNA (ssDNA) binding proteins from the Whirly family, thus indicating that these proteins could contribute to the accurate repair of plant organelle genomes. To understand the role of Whirly proteins in this process, we solved the crystal structures of several Whirly-DNA complexes. These reveal a nonsequence-specific ssDNA binding mechanism in which DNA is stabilized between domains of adjacent subunits and rendered unavailable for duplex formation and/or protein interactions. Our results suggest a model in which the binding of Whirly proteins to ssDNA would favor accurate repair of DNA double-strand breaks over an error-prone microhomology-mediated break-induced replication repair pathway.     

The impact of herpes zoster and postherpetic neuralgia on health-related quality of life: a prospective study

Background

Vaccination against herpes zoster is being considered in many countries. We conducted a multicentre prospective study to describe the impact of herpes zoster and postherpetic neuralgia on health-related quality of life.

Methods

From October 2005 to July 2006, 261 outpatients aged 50 years or older with herpes zoster were recruited from the clinical practices of 83 physicians within 14 days after rash onset. The Zoster Brief Pain Inventory was used to measure severity of pain and interference with activities of daily living because of pain. The EuroQol EQ-5D assessment tool was used to measure quality of life. These outcomes were assessed at recruitment and on days 7, 14, 21, 30, 60, 90, 120, 150 and 180 following recruitment.

Results

Acute herpes zoster interfered in all health domains, especially sleep (64% of participants), enjoyment of life (58%) and general activities (53%). The median duration of pain was 32.5 days. The median duration of interference with activities of daily living because of pain varied between 27 and 30 days. Overall, 24% of the participants had postherpetic neuralgia (pain for more than 90 days after rash onset). Anxiety and depression, enjoyment of life, mood and sleep were most frequently affected during the postherpetic neuralgia period. The mean EQ-5D score was 0.59 at enrolment and remained at 0.67 at all follow-up points among participants who reported clinically significant pain.

Interpretation

These data support the need for preventive strategies and additional early intervention to reduce the burden of herpes zoster and postherpetic neuralgia.Herpes zoster, which is characterized by dermatomal pain and vesicular rash,^1,2 results from reactivation of the varicella-zoster virus.^3,4 The average lifetime risk of herpes zoster in developed countries is estimated to be about 30%^5–7 and increases with increasing life expectancy. The most common complication of herpes zoster, and one of the most challenging to treat, is postherpetic neuralgia, a painful condition often defined as pain persisting for more than 90 days after rash onset.⁸ According to this definition, postherpetic neuralgia is estimated to occur in 8%–27% of people with herpes zoster overall.^9–14 The risk of postherpetic neuralgia increases markedly with age.¹⁵The Shingles Prevention Study, a randomized double-blind placebo-controlled trial, showed that a live-attenuated varicella-zoster virus vaccine was safe and effective in preventing herpes zoster and postherpetic neuralgia among people 60 years of age and older.¹³ Given these promising results, policy-makers and clinicians are being asked to make recommendations regarding the use and funding of the herpes zoster vaccine. To do this, evidence on the burden of herpes zoster from the patient’s perspective is required. The only data available on the impact of herpes zoster on health-related quality of life comes from two short-term studies.^16,17 Clinical reports and cross-sectional surveys^18–20 have also suggested that postherpetic neuralgia can profoundly impair quality of life. However, no study followed a cohort of patients with newly diagnosed herpes zoster for a sufficient period to assess postherpetic neuralgia and describe the associated impact on quality of life.We undertook a multicentre prospective study to describe the impact of herpes zoster and postherpetic neuralgia on health-related quality of life.     

Genetic analysis of 103 candidate genes for coronary artery disease and associated phenotypes in a founder population reveals a new association between endothelin-1 and high-density lipoprotein cholesterol

Coronary artery disease (CAD) is a major health concern in both developed and developing countries. With a heritability estimated at ~50%, there is a strong rationale to better define the genetic contribution to CAD. This project involves the analysis of 884 individuals from 142 families (with average sibships of 5.7) as well as 558 case and control subjects from the Saguenay Lac St-Jean region of northeastern Quebec, with the use of 1,536 single-nucleotide polymorphisms (SNPs) in 103 candidate genes for CAD. By use of clusters of SNPs to generate multiallelic haplotypes at candidate loci for segregation studies within families, suggestive linkage for high-density lipoprotein (HDL) cholesterol is observed on chromosome 1p36.22. Furthermore, several associations that remain significant after Bonferroni correction are observed with lipoprotein-related traits as well as plasma concentrations of adiponectin. Of note, HDL cholesterol levels are associated with an amino acid substitution (lysine/asparagine) at codon 198 (rs5370) of endothelin-1 (EDN1) in a sex-specific manner, as well as with a SNP (rs2292318) located 7.7 kb upstream of lecithin cholesterol acyl-transferase (LCAT). Whereas the other observed associations are described in the current literature, these two are new. Using an independent validation sample of 806 individuals, we confirm the EDN1 association (P<.005), whereas the LCAT association was nonsignificant (P=.12).     

Identification and biochemical characterization of two novel UDP-2,3-diacetamido-2,3-dideoxy-alpha-D-glucuronic acid 2-epimerases from respiratory pathogens

For a long period lactate was considered as a dead-end product of glycolysis in many cells and its accumulation correlated with acidosis and cellular and tissue damage. At present, the role of lactate in several physiological processes has been investigated based on its properties as an energy source, a signalling molecule and as essential for tissue repair. It is noteworthy that lactate accumulation alters glycolytic flux independently from medium acidification, thereby this compound can regulate glucose metabolism within cells. PFK (6-phosphofructo-1-kinase) is the key regulatory glycolytic enzyme which is regulated by diverse molecules and signals. PFK activity is directly correlated with cellular glucose consumption. The present study shows the property of lactate to down-regulate PFK activity in a specific manner which is not dependent on acidification of the medium. Lactate reduces the affinity of the enzyme for its substrates, ATP and fructose 6-phosphate, as well as reducing the affinity for ATP at its allosteric inhibitory site at the enzyme. Moreover, we demonstrated that lactate inhibits PFK favouring the dissociation of enzyme active tetramers into less active dimers. This effect can be prevented by tetramer-stabilizing conditions such as the presence of fructose 2,6-bisphosphate, the binding of PFK to f-actin and phosphorylation of the enzyme by protein kinase A. In conclusion, our results support evidence that lactate regulates the glycolytic flux through modulating PFK due to its effects on the enzyme quaternary structure.     

Aberrant allele frequencies of the SNPs located in microRNA target sites are potentially associated with human cancers

MicroRNAs (miRNAs) are a class of noncoding small RNAs that regulate gene expression by base pairing with target mRNAs at the 3'-terminal untranslated regions (3'-UTRs), leading to mRNA cleavage or translational repression. Single-nucleotide polymorphisms (SNPs) located at miRNA-binding sites (miRNA-binding SNPs) are likely to affect the expression of the miRNA target and may contribute to the susceptibility of humans to common diseases. We herein performed a genome-wide analysis of SNPs located in the miRNA-binding sites of the 3'-UTR of various human genes. We found that miRNA-binding SNPs are negatively selected in respect to SNP distribution between the miRNA-binding 'seed' sequence and the entire 3'-UTR sequence. Furthermore, we comprehensively defined the expression of each miRNA-binding SNP in cancers versus normal tissues through mining EST databases. Interestingly, we found that some miRNA-binding SNPs exhibit significant different allele frequencies between the human cancer EST libraries and the dbSNP database. More importantly, using human cancer specimens against the dbSNP database for case-control association studies, we found that twelve miRNA-binding SNPs indeed display an aberrant allele frequency in human cancers. Hence, SNPs located in miRNA-binding sites affect miRNA target expression and function, and are potentially associated with cancers.     

Maternal immunity and mother-to-child transmission of HCV and HIV-1: challenges and recent advances

Human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) are two viral pathogens that establish chronic infections in their hosts and that are at present responsible for serious public health problems on a pandemic scale. HIV-1 and HCV can be transmitted from person to person by contact with bodily fluids. Both can also be transmitted from mother to child during the course of pregnancy and childbirth. There are currently no vaccines available to immunize against HIV-1 and HCV infection or to prevent mother-to-child transmission (MTCT), and accessible treatments have significant yet limited efficacy. However, important progresses have been made since the discovery of HCV and HIV-1 : (a) sensitive screening and detection methods have been perfected ; (b) risk factors for acquisition, replicative cycles, pathogenesis, and mechanisms of transmission have been better characterized ; (c) specific treatments, immunotherapy, and antiretroviral prophylaxis regimen were developed ; (d) immune correlates of protection are better understood ; and (e) vaccine design was undertaken. In addition, co-infection with HCV and HIV-1, which is common among high-risk groups including injection drug users, significantly increases the incidence of MTCT of both viruses. The mechanisms by which this facilitation occurs are still under investigation and may involve direct replicative facilitation, enhancement of placental transfer, and/or interference with host immune responses. Taken together, these developments could lead to the implementation of global scale strategies to prevent MTCT of HCV and HIV-1.     

Vestibular signal processing in a subject with somatosensory deafferentation: The case of sitting posture

Background  

The vestibular system of the inner ear provides information about head translation/rotation in space and about the orientation of the head with respect to the gravitoinertial vector. It also largely contributes to the control of posture through vestibulospinal pathways. Testing an individual severely deprived of somatosensory information below the nose, we investigated if equilibrium can be maintained while seated on the sole basis of this information.