Lipoprotein DolP supports proper folding of BamA in the bacterial outer membrane promoting fitness upon envelope stress.

In Proteobacteria, integral outer membrane proteins (OMPs) are crucial for the maintenance of the envelope permeability barrier to some antibiotics and detergents. In Enterobacteria, envelope stress caused by unfolded OMPs activates the sigmaE (σE) transcriptional response. σE upregulates OMP biogenesis factors, including the ß-barrel assembly machinery (BAM) that catalyses OMP folding. Here we report that DolP (formerly YraP), a σE-upregulated and poorly understood outer membrane lipoprotein, is crucial for fitness in cells that undergo envelope stress. We demonstrate that DolP interacts with the BAM complex by associating with outer membrane-assembled BamA. We provide evidence that DolP is important for proper folding of BamA that overaccumulates in the outer membrane, thus supporting OMP biogenesis and envelope integrity. Notably, mid-cell recruitment of DolP had been linked to regulation of septal peptidoglycan remodelling by an unknown mechanism. We now reveal that, during envelope stress, DolP loses its association with the mid-cell, thereby suggesting a mechanistic link between envelope stress caused by impaired OMP biogenesis and the regulation of a late step of cell division.

Transmembrane Coordination of Preprotein Recognition and Motor Coupling by the Mitochondrial Presequence Receptor Tim50.

Mitochondrial preproteins contain amino-terminal presequences directing them to the presequence translocase of the mitochondrial inner membrane (TIM23 complex). Depending on additional downstream import signals, TIM23 either inserts preproteins into the inner membrane or translocates them into the matrix. Matrix import requires the coupling of the presequence translocase-associated motor (PAM) to TIM23. The molecular mechanisms coordinating preprotein recognition by TIM23 in the intermembrane space (IMS) with PAM activation in the matrix are unknown. Here we show that subsequent to presequence recognition in the IMS, the Tim50 matrix domain facilitates the recruitment of the coupling factor Pam17. Next, the IMS domain of Tim50 promotes PAM recruitment to TIM23. Finally, the Tim50 transmembrane segment stimulates the matrix-directed import-driving force exerted by PAM. We propose that recognition of preprotein segments in the IMS and transfer of signal information across the inner membrane by Tim50 determine import motor activation.

Mitochondrial presequence import: Multiple regulatory knobs fine-tune mitochondrial biogenesis and homeostasis.

Mitochondria are pivotal organelles for cellular signaling and metabolism, and their dysfunction leads to severe cellular stress. About 60-70% of the mitochondrial proteome consists of preproteins synthesized in the cytosol with an amino-terminal cleavable presequence targeting signal. The TIM23 complex transports presequence signals towards the mitochondrial matrix. Ultimately, the mature protein segments are either transported into the matrix or sorted to the inner membrane. To ensure accurate preprotein import into distinct mitochondrial sub-compartments, the TIM23 machinery adopts specific functional conformations and interacts with different partner complexes. Regulatory subunits modulate the translocase dynamics, tailoring the import reaction to the incoming preprotein. The mitochondrial membrane potential and the ATP generated via oxidative phosphorylation are key energy sources in driving the presequence import pathway. Thus, mitochondrial dysfunctions have rapid repercussions on biogenesis. Cellular mechanisms exploit the presequence import pathway to monitor mitochondrial dysfunctions and mount transcriptional and proteostatic responses to restore functionality.

Use of a neuro-variational inversion for retrieving oceanic and atmospheric constituents from satellite ocean colour sensor: application to absorbing aerosols.

This paper presents a new development of the NeuroVaria method. NeuroVaria computes relevant atmospheric and oceanic parameters by minimizing the difference between the observed satellite reflectances and those computed from radiative transfer simulations modelled by artificial neural networks. Aerosol optical properties are computed using the Junge size distribution allowing taking into account highly absorbing aerosols. The major improvement to the method has been to implement an iterative cost function formulation that makes the minimization more efficient. This implementation of NeuroVaria has been applied to sea-viewing wide field-of-view sensor (SeaWiFS) imagery. A comparison with in situ measurements and the standard SeaWiFS results for cases without absorbing aerosols shows that this version of NeuroVaria remains consistent with the former. Finally, the processing of SeaWiFS images of a plume of absorbing aerosols off the US East coast demonstrate the ability of this improved version of NeuroVaria to deal with absorbing aerosols.

A home blood pressure monitoring study comparing the antihypertensive efficacy of two angiotensin II receptor antagonist fixed combinations.

BACKGROUND: The objective of this prospective, randomized, open-label, blinded-endpoint study was to compare the antihypertensive efficacy of valsartan 80 mg v irbesartan 150 mg when combined with hydrochlorothiazide (HCTZ) 12.5 mg. METHODS: Untreated or uncontrolled hypertensive adults (n = 800) were enrolled by primary care physicians. After a 5-week open-label lead-in phase in which all patients received 12.5 mg HCTZ once daily, subjects whose blood pressure (BP) remained uncontrolled were randomized (n = 464) to valsartan/HCTZ (80/12.5 mg) or irbesartan/HCTZ (150/12.5 mg) for 8 weeks. Home BP monitoring (HBPM) was performed in the morning and in the evening for 5 days, at baseline, and after 8 weeks. Office BP measurements were obtained at baseline and after 8 weeks. RESULTS: Irbesartan/HCTZ produced greater reductions in average systolic BP (SBP) and diastolic BP (DBP) measured by HBPM than valsartan/HCTZ (SBP: -13.0 v -10.6 mm Hg, P = .0094; DBP: -9.5 v -7.4 mm Hg, P = .0007). These differences were more pronounced in the morning (trough) than in the evening. Office BP measurements also showed greater reductions in trough seated SBP and DBP with irbesartan/HCTZ compared with valsartan/HCTZ. Normalization rates observed with HBPM (SBP <135 mm Hg and DBP <85 mm Hg) were significantly greater with irbesartan/HCTZ than with valsartan/HCTZ (50.2 v 33.2%; P = .0003). The overall safety was similar in the two groups. CONCLUSIONS: The superior BP-lowering potency of the fixed combination irbesartan/HCTZ (150/12.5 mg) over valsartan/HCTZ (80/12.5 mg), evidenced independently from the investigators by HBPM, supports the use of this technique in trials with prospective, randomized, open-label, blinded-endpoint designs.