The sulfolipid sulfoquinovosyldiacylglycerol is present in the photosynthetic membranes of plants and many photosynthetic bacteria. A novel gene, sqdX, essential for sulfolipid biosynthesis in the cyanobacterium Synechococcus sp. strain PCC7942 is proposed to encode the cyanobacterial sulfolipid synthase catalyzing the last reaction of the pathway.

The photosynthetic reaction center is one of the most complicated molecular complexes. Transducing photon energy to a transmembrane electrochemical potential difference for protons, it is the direct or indirect energy source for virtually all life. We show here that it operates in a simple, battery-like manner, with a maximum potential of 0.20 V. Intriguingly this is only one fifth of the energ...

Regulation of photosynthetic light harvesting in the thylakoids is one of the major key factors affecting the efficiency of photosynthesis. Thylakoid membrane is negatively charged and influences both the structure and the function of the primarily photosynthetic reactions through its electrical double layer (EDL). Further, there is a heterogeneous organization of soluble ions (K+, Mg2+, Cl-) a...

1. Two dyes, bromocresol purple and ethyl red, were tested for their ability to register solution and membrane changes resulting from the illumination of suspensions of isolated chloroplasts. 2. Bromocresol purple can measure the external (suspension) pH both rapidly and accurately if the following precautions are observed: (a) since bromocresol purple stimulates electron flow to oxygen, either...

We have investigated the structure of the photosynthetic membrane in a mutant of barley known to lack a chlorophyll-binding protein. This protein is thought to channel excitation energy to photosystem II, and is known as the "light-harvesting chlorophyll-protein complex." Extensive stacking of thylakoids into grana occurs in both mutant and wild-type chloroplasts. Examination of membrane intern...

Robert Huber and his colleagues, Johann Deisenhofer and Hartmut Michel, elucidated the three-dimensional structure of the Rhodopseudomonas viridis photosynthetic reaction center. This membrane protein complex is a basic component of photosynthesis - a process fundamental to life on Earth - and for their work, Huber and his colleagues received the 1988 Nobel Prize in Chemistry. Because structura...

We have previously demonstrated (Armond, P. A., C. J. Arntzen, J.-M. Briantais, and C. Vernotte. 1976. Arch. Biochem. Biophys. 175:54-63; and Davis, D. J., P. A. Armond, E. L. Gross, and C. J. Arntzen. 1976. Arch. Biochem. Biophys. 175:64-70) that pea seedlings which were exposed to intermittent illumination contained incompletely developed chloroplasts. These plastids were photosynthetically c...

The study of the analytical cytology of the bacterial cell was initiated with the work of Schachman et al. (1952), which revealed the presence of a variety of particles in extracts of many microorganisms. Since that time, numerous workers have isolated and characterized some of these particles. This work has been thoroughly reviewed by Alexander (1956). More recent studies (Cota-Robles et al., ...

The α-proteobacterium Rhodobacter sphaeroides is an exemplary model organism for the creation and study of novel protein expression systems, especially membrane protein complexes that harvest light energy to yield electrical energy. Advantages of this organism include a sequenced genome, tools for genetic engineering, a well-characterized metabolism, and a large membrane surface area when grown...