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Phenotypic analysis of five Acinetobacter calcoaceticus mutants lacking extracellular lipase, which were generated via insertion mutagenesis, revealed four lipolytic enzymes. Biochemical tests classified four mutants as export mutants, while the additional mutant, designated AAC302, exhibited showed mutation 0.84 kbp upstream of lipA, although it displayed the LipA- phenotype. DNA sequencing of the region revealed an open reading frame that encodes a protein required for the production of extracellular lipase. It is suggested that this protein acts as a lipase-specific chaperone.

The photocycle of the AppA BLUF domain by ultrafast fluorescence, femtosecond transient absorption, and nanosecond flash-photolysis spectroscopy is investigated. Time-resolved fluorescence experiments have shown that the decay of excited AppA-bound flavin adenine dinucleotide (FAD) is highly multiexponential.

NMR spectroscopy has investigated that the formation of a negative charge is prohibited at position 46 upon formation of pB in the absence of the carboxylic group near the chromophore in the E46Q mutant, which prevents the partial unfolding of the mutant.

31P nuclear magnetic resonance spectra of the spectra phototrophic bacterium (Rhodopseudomonas sphaeroides reveal the presence of inorganic phosphate, sugar phosphates and two non-identified P,P¹-diesterified pyrophosphate compounds. Due to the presence of paramagnetic cations the resonances of these compounds can only be detected after repeated washing of the bacterial cells with a buffer, containing EDTA plus excess Mg2+. Washing with Mg2+-free EDTA buffer deteriorates the structural integrity of the membranes of Rps. sphaeroides. This is indicated by the appearance of an extra resonance peak in the spectra of these cells in a region where the phospholipids absorb and by a fivefold increase in proton permeability of the cytoplasmic membrane of Rps. sphaeroides under these conditions. Upon illumination of the cell suspension in the NMR tube the generation of a transmembrane pH gradient can be inferred from the shift in the resonances of extracellular and intracellular inorganic phosphate. Intracellular inorganic phosphate shows one homogeneous resonance peak upon illumination. This demonstrates that the mixing system, which has been developed for this application, functions efficiently. The magnitude of the light-dependent pH difference is 0.8 at an external pH 6. The width at half height of the internal inorganic phosphate peak is essentially independents of internal pH from pH 5-8, remains unchanged upon addition of uncoupler and is inversely proportional to the number of EDTA washings applied. These observations indicate that the inorganic phosphate NMR peak width is predominantly determined by the presence of a residual amount of paramagnetic cations, rather than by a broad distributions of internal pH values over the cells. Ionophores have an effect on the light-dependent pH-gradient in accordance with the cemiosnotic theory; valinomycin increases, and carbonylcyanide p-trifluoromenthoxyphenylhydrazone decreases, the magnitude of this gradient. [ABSTRACT FROM AUTHOR]