Impact of acute partial-body cryostimulation on cognitive performance, cerebral oxygenation, and cardiac autonomic activity

We assessed the effects of a 3-min partial-body cryostimulation (PBC) exposure -where the whole body is exposed to extreme cold, except the head- on cognitive inhibition performance and the possible implications of parasympathetic cardiac control and cerebral oxygenation. In a randomized controlled counterbalanced cross-over design, eighteen healthy young adults (nine males and nine females) completed a cognitive Stroop task before and after one single session of PBC (3-min exposure at -150ºC cold air) and a control condition (3 minutes at room temperature, 20ºC). During the cognitive task, heart rate variability (HRV) and cerebral oxygenation of the prefrontal cortex were measured using heart rate monitoring and near-infrared spectroscopy methods. We also recorded the cerebral oxygenation during the PBC session. Stroop performance after PBC exposure was enhanced (562.0 ± 40.2 ms) compared to pre-PBC (602.0 ± 56.4 ms; P < 0.042) in males only, accompanied by an increase (P < 0.05) in HRV indices of parasympathetic tone, in greater proportion in males compared to females. During PBC, cerebral oxygenation decreased in a similar proportion in males and females but the cerebral extraction (deoxyhemoglobin: ΔHHb) remained higher after exposure in males, only. These data demonstrate that a single PBC session enhances the cognitive inhibition performance on a Stroop task in males, partly mediated by a greater parasympathetic cardiac control and greater cerebral oxygenation. The effects of PBC on cognitive function seem different in females, possibly explained by a different sensitivity to cold stimulation

Decoding the Folding of Burkholderia glumae Lipase: Folding Intermediates En Route to Kinetic Stability

The lipase produced by Burkholderia glumae folds spontaneously into an inactive near-native state and requires a periplasmic chaperone to reach its final active and secretion-competent fold. The B. glumae lipase-specific foldase (Lif) is classified as a member of the steric-chaperone family of which the propeptides of α-lytic protease and subtilisin are the best known representatives. Steric chaperones play a key role in conferring kinetic stability to proteins. However, until present there was no solid experimental evidence that Lif-dependent lipases are kinetically trapped enzymes. By combining thermal denaturation studies with proteolytic resistance experiments and the description of distinct folding intermediates, we demonstrate that the native lipase has a kinetically stable conformation. We show that a newly discovered molten globule-like conformation has distinct properties that clearly differ from those of the near-native intermediate state. The folding fingerprint of Lif-dependent lipases is put in the context of the protease-prodomain system and the comparison reveals clear differences that render the lipase-Lif systems unique. Limited proteolysis unveils structural differences between the near-native intermediate and the native conformation and sets the stage to shed light onto the nature of the kinetic barrier

Structure of the Pseudomonas aeruginosa XcpT pseudopilin, a major component of the type II secretion system.

The bacterial type II protein secretion (T2S) and type IV piliation (T4P) systems share several common features. In particular, it is well established that the T2S system requires the function of a pilus-like structure, called pseudopilus, which is built upon assembly of pilin-like subunits, called pseudopilins. Pilins and pseudopilins have a hydrophobic N-terminal region, which precedes an extended hydrophilic C-terminal region. In the case of pilins, it was shown that oligomerisation and formation of helical fibers, takes place through interaction between the hydrophobic domains. XcpT, is the most abundant protein of the Pseudomonas aeruginosa T2S, and was proposed to be the main component in the pseudopilus. In this study we present the high-resolution NMR structure of the hydrophilic domain of XcpT (XcpTp). XcpTp is lacking the C-terminal disulfide bridged &quot;D&quot; domain found in type IV pilins and likely involved in receptor binding. This is in agreement with the idea that the XcpT-containing pseudopilus is required for protein secretion and not for bacterial attachment. Interestingly, by solving the 3D structure of XcpTp we revealed that the previously called alphabeta-loop pilin region is in fact highly conserved among major type II pseudopilins and constitutes a specific consensus motif for identifying major pseudopilins, which belong to this family