Annealing of ssDNA and compaction of dsDNA by the HIV-1 nucleocapsid and Gag proteins visualized using nanofluidic channels

The nucleocapsid protein NC is a crucial component in the human immunodeficiency virus type 1 life cycle. It functions both in its processed mature form and as part of the polyprotein Gag that plays a key role in the formation of new viruses. NC can protect nucleic acids (NAs) from degradation by compacting them to a dense coil. Moreover, through its NA chaperone activity, NC can also promote the most stable conformation of NAs. Here, we explore the balance between these activities for NC and Gag by confining DNA-protein complexes in nanochannels. The chaperone activity is visualized as concatemerization and circularization of long DNA via annealing of short single-stranded DNA overhangs. The first ten amino acids of NC are important for the chaperone activity that is almost completely absent for Gag. Gag condenses DNA more efficiently than mature NC, suggesting that additional residues of Gag are involved. Importantly, this is the first single DNA molecule study of full-length Gag and we reveal important differences to the truncated Δ-p6 Gag that has been used before. In addition, the study also highlights how nanochannels can be used to study reactions on ends of long single DNA molecules, which is not trivial with competing single DNA molecule techniques

The nucleic acid chaperone activity of the HIV-1 Gag polyprotein is boosted by its cellular partner RPL7: a kinetic study

10.1093/nar/gkaa659Nucleic Acids Researc

Systemic down-regulation of delta-9 desaturase promotes muscle oxidative metabolism and accelerates muscle function recovery following nerve injury.

The progressive deterioration of the neuromuscular axis is typically observed in degenerative conditions of the lower motor neurons, such as amyotrophic lateral sclerosis (ALS). Neurodegeneration in this disease is associated with systemic metabolic perturbations, including hypermetabolism and dyslipidemia. Our previous gene profiling studies on ALS muscle revealed down-regulation of delta-9 desaturase, or SCD1, which is the rate-limiting enzyme in the synthesis of monounsaturated fatty acids. Interestingly, knocking out SCD1 gene is known to induce hypermetabolism and stimulate fatty acid beta-oxidation. Here we investigated whether SCD1 deficiency can affect muscle function and its restoration in response to injury. The genetic ablation of SCD1 was not detrimental per se to muscle function. On the contrary, muscles in SCD1 knockout mice shifted toward a more oxidative metabolism, and enhanced the expression of synaptic genes. Repressing SCD1 expression or reducing SCD-dependent enzymatic activity accelerated the recovery of muscle function after inducing sciatic nerve crush. Overall, these findings provide evidence for a new role of SCD1 in modulating the restorative potential of skeletal muscles

Blood Cell Palmitoleate-Palmitate Ratio Is an Independent Prognostic Factor for Amyotrophic Lateral Sclerosis.

Growing evidence supports a link between fatty acid metabolism and amyotrophic lateral sclerosis (ALS). Here we determined the fatty acid composition of blood lipids to identify markers of disease progression and survival. We enrolled 117 patients from two clinical centers and 48 of these were age and gender matched with healthy volunteers. We extracted total lipids from serum and blood cells, and separated fatty acid methyl esters by gas chromatography. We measured circulating biochemical parameters indicative of the metabolic status. Association between fatty acid composition and clinical readouts was studied, including ALS functional rating scale-revised (ALSFRS-R), survival, disease duration, site of onset and body mass index. Palmitoleate (16:1) and oleate (18:1) levels, and stearoyl-CoA desaturase indices (16:1/16:0 and 18:1/18:0) significantly increased in blood cells from ALS patients compared to healthy controls. Palmitoleate levels and 16:1/16:0 ratio in blood cells, but not body mass index or leptin concentrations, negatively correlated with ALSFRS-R decline over a six-month period (p<0.05). Multivariate Cox analysis, with age, body mass index, site of onset and ALSFRS-R as covariables, showed that blood cell 16:1/16:0 ratio was an independent prognostic factor for survival (hazard ratio=0.1 per unit of ratio, 95% confidence interval=0.01-0.57, p=0.009). In patients with high 16:1/16:0 ratio, survival at blood collection was extended by 10 months, as compared to patients with low ratio. The 16:1/16:0 index is an easy-to-handle parameter that predicts survival of ALS patients independently of body mass index. It therefore deserves further validation in larger cohorts for being used to assess disease outcome and effects of disease-modifying drugs

Blood cell 16:1/16:0 ratio correlates with disease progression and affects survival of ALS patients.

<p>Correlation between 16:1/16:0 and 18:0/18:1 ratios and disease duration (A, E) at blood collection or ALSFRS-R slope (B, F), determined as the decline of the score over a period of six months starting at the point of blood collection. Correlation coefficients (r) and <i>p</i>-values are indicated. n.s., non-significant <i>p</i>-value (Spearman test, n = 111). Based on the median ratio of the population, ALSFRS-R decline is shown in patients with low or high 16:1/16:0 ratio (C), and in patients with low or high 18:1/18:0 ratio (G). *<i>p</i><0.05 (Mann-Withney test). (D, H) Kaplan-Meier curves of survival in the subgroups of patients as above. Survival was the interval between the point of blood collection and death. <i>P</i>-values are indicated (Gehan-Breslow-Wilcoxon test, n = 117).</p

SCD indices are higher in ALS patients than in control subjects.

<p>(A) Palmitoleate to palmitate ratio (16:1/16:0) in serum and blood cells from ALS patients (ALS) and control subjects (CT). (B) Oleate to stearate ratio (18:1/18:0) in serum and blood cells from ALS patients (ALS) and control subjects (CT). *<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001 (Mann-Withney test, n = 48).</p

Analysis of the survival of ALS patients using multivariate Cox proportional hazards model.

<p>Analysis of the survival of ALS patients using multivariate Cox proportional hazards model.</p