Escherichia coli expression and purification of four antimicrobial peptides fused to a family 3 carbohydrate-binding module (CBM) from Clostridium thermocellum

Antimicrobial peptides (AMPs) are molecules that act in a wide range of physiological defensive mechanisms developed to counteract bacteria, fungi, parasites and viruses. Several hundreds of AMPs have been identified and characterized. These molecules are presently gaining increasing importance, as a consequence of their remarkable resistance to microorganism adaptation. Carbohydrate-binding modules (CBMs) are non-catalytic domains that anchor glycoside hydrolases into complex carbohydrates. Clostridium thermocellum produces a multi-enzyme complex of cellulases and hemicellulases, termed the cellulosome, which is organized by the scaffoldin protein CipA. Binding of the cellulosome to the plant cell wall results from the action of CipA family 3 CBM (CBM3), which presents a high affinity for crystalline cellulose. Here CipA family 3 CBM was fused to four different AMPs using recombinant DNA technology and the fusion recombinant proteins were expressed at high levels in Escherichia coli cells. CBM3 does not present antibacterial activity and does not bind to the bacterial surface. However, the four recombinant proteins retained the ability to bind cellulose, suggesting that CBM3 is a good candidate polypeptide to direct the binding of AMPs into cellulosic supports. A comprehensive characterization of the antimicrobial activity of the recombinant fusion proteins is currently under evaluation.Instituto de Tecnologia Química e Biológica,Fundação para a Ciência e a Tecnologia (FCT

Burden, coping, physical symptoms and psychological morbidity in caregivers of functionally dependent family members

Objectives: this study assessed burden, coping, physical symptoms and psychological morbidity in caregivers of functionally dependent family members. Methods: fifty family caregivers completed self-reported measures of burden, physical symptoms, psychological morbidity and coping strategies. Results: there was a significant negative correlation between coping strategies and the different clinical variables, as well as a significant positive correlation between coping strategies and duration of care. It appears that the stronger bond between caregiver and family member leads to a poorer use of adaptive coping strategies. It also appears that the deterioration of the relationship between them and the lower perceived self-efficacy are more prominente in caregivers of family members with cognitive impairment, indicating that caregivers with family members without cognitive impairment face fewer difficulties. Conclusion: these results emphasize the need for interventions to include coping strategies, since they are important in reducing caregivers’ burden, psychological morbidity and physical symptoms

Association of HFE common mutations with Parkinson's disease, Alzheimer's disease and mild cognitive impairment in a Portuguese cohort

Background: Pathological brain iron deposition has been implicated as a source of neurotoxic reactive oxygen species in Alzheimer (AD) and Parkinson diseases (PD). Iron metabolism is associated with the gene hemochromatosis (HFE Human genome nomenclature committee ID: 4886), and mutations in HFE are a cause of the iron mismetabolism disease, hemochromatosis. Several reports have tested the association of HFE variants with neurodegenerative diseases, such as AD and PD with conflicting results.Methods: Genotypes were analysed for the two most common variants of HFE in a series of 130 AD, 55 Mild Cognitive Impairment (MCI) and 132 PD patients. Additionally, a series of 115 healthy age-matched controls was also screened.Results: A statistically significant association was found in the PD group when compared to controls, showing that the presence of the C282Y variant allele may confer higher risk for developing the disease.Conclusion: Taken together these results suggest that the common variants in HFE may be a risk factor for PD, but not for AD in the Portuguese population

Disease-related cortical thinning in presymptomatic granulin mutation carriers

Mutations in the granulin gene (GRN) cause familial frontotemporal dementia. Understanding the structural brain changes in presymptomatic GRN carriers would enforce the use of neuroimaging biomarkers for early diagnosis and monitoring. We studied 100 presymptomatic GRN mutation carriers and 94 noncarriers from the Genetic Frontotemporal dementia initiative (GENFI), with MRI structural images. We analyzed 3T MRI structural images using the FreeSurfer pipeline to calculate the whole brain cortical thickness (CTh) for each subject. We also perform a vertex-wise general linear model to assess differences between groups in the relationship between CTh and diverse covariables as gender, age, the estimated years to onset and education. We also explored differences according to TMEM106B genotype, a possible disease modifier. Whole brain CTh did not differ between carriers and noncarriers. Both groups showed age-related cortical thinning. The group-by-age interaction analysis showed that this age-related cortical thinning was significantly greater in GRN carriers in the left superior frontal cortex. TMEM106B did not significantly influence the age-related cortical thinning. Our results validate and expand previous findings suggesting a

Social cognition impairment in genetic frontotemporal dementia within the GENFI cohort

A key symptom of frontotemporal dementia (FTD) is difficulty interacting socially with others. Social cognition problems in FTD include impaired emotion processing and theory of mind difficulties, and whilst these have been studied extensively in sporadic FTD, few studies have investigated them in familial FTD. Facial Emotion Recognition (FER) and Faux Pas (FP) recognition tests were used to study social cognition within the Genetic Frontotemporal Dementia Initiative (GENFI), a large familial FTD cohort of C9orf72, GRN, and MAPT mutation carriers. 627 participants undertook at least one of the tasks, and were separated into mutation-negative healthy controls, presymptomatic mutation carriers (split into early and late groups) and symptomatic mutation carriers. Groups were compared using a linear regression model with bootstrapping, adjusting for age, sex, education, and for the FP recognition test, language. Neural correlates of social cognition deficits were explored using a voxel-based morphometry (VBM) study. All three of the symptomatic genetic groups were impaired on both tasks with no significant difference between them. However, prior to onset, only the late presymptomatic C9orf72 mutation carriers on the FER test were impaired compared to the control group, with a subanalysis showing differences particularly in fear and sadness. The VBM analysis revealed that impaired social cognition was mainly associated with a left hemisphere predominant network of regions involving particularly the striatum, orbitofrontal cortex and insula, and to a lesser extent the inferomedial temporal lobe and other areas of the frontal lobe. In conclusion, theory of mind and emotion processing abilities are impaired in familial FTD, with early changes occurring prior to symptom onset in C9orf72 presymptomatic mutation carriers. Future work should investigate how performance changes over time, in order to gain a clearer insight into social cognitive impairment over the course of the disease

Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes

Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson’s disease (PD) and Alzheimer’s disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues

T7 Endonuclease I Mediates Error Correction in Artificial Gene Synthesis

International audienceno abstrac

Development of a gene synthesis platform for the efficient large scale production of small genes encoding animal toxins

International audienceBackgroundGene synthesis is becoming an important tool in many fields of recombinant DNA technology, including recombinant protein production. De novo gene synthesis is quickly replacing the classical cloning and mutagenesis procedures and allows generating nucleic acids for which no template is available. In addition, when coupled with efficient gene design algorithms that optimize codon usage, it leads to high levels of recombinant protein expression.ResultsHere, we describe the development of an optimized gene synthesis platform that was applied to the large scale production of small genes encoding venom peptides. This improved gene synthesis method uses a PCR-based protocol to assemble synthetic DNA from pools of overlapping oligonucleotides and was developed to synthesise multiples genes simultaneously. This technology incorporates an accurate, automated and cost effective ligation independent cloning step to directly integrate the synthetic genes into an effective Escherichia coli expression vector. The robustness of this technology to generate large libraries of dozens to thousands of synthetic nucleic acids was demonstrated through the parallel and simultaneous synthesis of 96 genes encoding animal toxins.ConclusionsAn automated platform was developed for the large-scale synthesis of small genes encoding eukaryotic toxins. Large scale recombinant expression of synthetic genes encoding eukaryotic toxins will allow exploring the extraordinary potency and pharmacological diversity of animal venoms, an increasingly valuable but unexplored source of lead molecules for drug discovery