Incorporating clickers into an enzymology course improves student performance.

Here, we describe how poor exam results of undergraduate students enrolled in an enzymology course at the University of Bordeaux were improved through the introduction of 'clickers' as an audience response system. By using clickers only in a small-group tutorial element of a large theoretical course, we observed an improvement in exam scores that resulted in a lower failure rate for the course. Furthermore, students of all abilities were found to benefit from their use.

Human F1F0 ATP synthase, mitochondrial ultrastructure and OXPHOS impairment: a (super-)complex matter?

Mitochondrial morphogenesis is a key process of cell physiology. It is essential for the proper function of this double membrane-delimited organelle, as it ensures the packing of the inner membrane in a very ordered pattern called cristae. In yeast, the mitochondrial ATP synthase is able to form dimers that can assemble into oligomers.

ATP synthase oligomerization: from the enzyme models to the mitochondrial morphology.

Mitochondrial F(1)F(o) ATP synthase is an enzymatic complex involved in the aerobic synthesis of ATP. It is well known that several enzymes are organized in supramolecular complexes in the inner mitochondrial membrane. The ATP synthase supramolecular assembly is mediated through two interfaces.

Rotor architecture in the yeast and bovine F1-c-ring complexes of F-ATP synthase.

The F(1)F(O)-ATP synthase is a rotary molecular nanomotor. F(1) is a chemical motor driven by ATP hydrolysis while F(O) is an electrical motor driven by the proton flow. The two stepping motors are mechanically coupled through a common rotary shaft.

Supramolecular organization of the yeast F1Fo-ATP synthase.

Background Information: The yeast mitochondrial F(1)F(o)-ATP synthase is a large complex of 600 kDa that uses the proton electrochemical gradient generated by the respiratory chain to catalyse ATP synthesis from ADP and P(i). For a large range of organisms, it has been shown that mitochondrial ATP synthase adopts oligomeric structures. Moreover, several studies have suggested that a link exists between ATP synthase and mitochondrial morphology.

A rivet model for channel formation by aerolysin-like pore-forming toxins.

The bacterial toxin aerolysin kills cells by forming heptameric channels, of unknown structure, in the plasma membrane. Using disulfide trapping and cysteine scanning mutagenesis coupled to thiol-specific labeling on lipid bilayers, we identify a loop that lines the channel. This loop has an alternating pattern of charged and uncharged residues, suggesting that the transmembrane region has a beta-barrel configuration, as observed for Staphylococcal alpha-toxin.

Flucytosine-fluconazole cross-resistance in purine-cytosine permease-deficient Candida lusitaniae clinical isolates: indirect evidence of a fluconazole uptake transporter.

An unusual interaction between flucytosine and fluconazole was observed when a collection of 60 Candida lusitaniae clinical isolates was screened for cross-resistance. Among eight isolates resistant to flucytosine (MIC >/= 128 micro g/ml) and susceptible to fluconazole (0.5 < MIC < 2 micro g/ml), four became flucytosine-fluconazole cross resistant when both antifungals were used simultaneously.

Is there a relationship between the supramolecular organization of the mitochondrial ATP synthase and the formation of cristae?

Blue native polyacrylamide gel electrophoresis (BN-PAGE) analyses of detergent mitochondrial extracts have provided evidence that the yeast ATP synthase could form dimers. Cross-linking experiments performed on a modified version of the i-subunit of this enzyme indicate the existence of such ATP synthase dimers in the yeast inner mitochondrial membrane. We also show that the first transmembrane segment of the eukaryotic b-subunit (bTM1), like the two supernumerary subunits e and g, is required for dimerization/oligomerization of ATP synthases.

Conversion of a transmembrane to a water-soluble protein complex by a single point mutation.

Proteins exist in one of two generally incompatible states: either membrane associated or soluble. Pore-forming proteins are exceptional because they are synthesized as a water-soluble molecule but end up being located in the membrane -- that is, they are nonconstitutive membrane proteins. Here we report the pronounced effect of the single point mutation Y221G of the pore-forming toxin aerolysin.

Two ATP synthases can be linked through subunits i in the inner mitochondrial membrane of Saccharomyces cerevisiae.

Cross-linking experiments showed that the supernumerary subunit i is close to the interface between two ATP synthases. These data were used to demonstrate the presence of ATP synthase dimers in the inner mitochondrial membrane of Saccharomyces cerevisiae. A cysteine residue was introduced into the inter-membrane space located C-terminal part of subunit i.

The ATP synthase is involved in generating mitochondrial cristae morphology.

The inner membrane of the mitochondrion folds inwards, forming the cristae. This folding allows a greater amount of membrane to be packed into the mitochondrion. The data in this study demonstrate that subunits e and g of the mitochondrial ATP synthase are involved in generating mitochondrial cristae morphology.

In the absence of the first membrane-spanning segment of subunit 4(b), the yeast ATP synthase is functional but does not dimerize or oligomerize.

The N-terminal portion of the mitochondrial b-subunit is anchored in the inner mitochondrial membrane by two hydrophobic segments. We investigated the role of the first membrane-spanning segment, which is absent in prokaryotic and chloroplastic enzymes. In the absence of the first membrane-spanning segment of the yeast subunit (subunit 4), a strong decrease in the amount of subunit g was found.