Gene expression of the flagellar system is tightly controlled by external stimuli or intracellular signals. A general picture of this regulation has been obtained from studies of Salmonella enterica serovar Typhimurium. However, these regulatory mechanisms do not apply to all bacterial groups. In this study, we have investigated regulation of the flagellar genetic system in Rhodobacter sphaeroi...

Chemotaxis is vital cellular movement in response to environmental chemicals. Unlike the canonical chemotactic pathway in Escherichia coli, Rhodobacter sphaeroides has both transmembrane and cytoplasmic sensory clusters, with the latter possibly interacting with essential components in the electron transport system. However, the effect of the cytoplasmic sensor and the mechanism of signal integ...

The common precursor to all tetrapyrroles is 5-aminolevulinic acid (ALA), and in Rhodobacter sphaeroides its formation occurs via the Shemin pathway. ALA synthase activity is encoded by two differentially regulated genes in R. sphaeroides 2.4.1: hemA and hemT. In our investigations of hemA regulation, we applied transposon mutagenesis under aerobic conditions, followed by a selection that ident...

In this paper, we report the circular dichroism (CD) spectra of two types of LH2-only mutants of Rhodobacter sphaeroides. In the first, only the wild type LH2 is present, while i the second, the B800 binding site of LH2 has been either destabilized or removed. For the first time, we have identified a band in the CD spectrum of LH2, located at approximately 780 nm, that can be ascribed to the hi...

Carotenoids in the peripheral light-harvesting complexes (LH2) of the green mutant (GM309) of Rhodobacter sphaeroides were identified as containing neurosporenes, which lack the polar CH(3)O group, compared to spheroidenes in native-LH2 of R. sphaeroides 601. After LH2 complexes were treated with 1-anilino-8-naphthalene sulfonate (ANS), new energy transfer pathways from ANS or tryptophan to car...

Genertation of hydrogen by purple, non-sulfur bacteria of Rhodobacter sphaeroides O.U.001 was tested in photobioreactors made of different materials. Reactors made of ordinary sodium-type glass, borosilicate glass (Pyrex) or polycarbonate were applied in the present study. The applied medium containing malic acid and sodium glutamate inoculated with 0.11 or 0.31 g dry wt. of Rhodobacater sphaer...

Gene expression of the flagellar system is tightly controlled by external stimuli or intracellular signals. A general picture of this regulation has been obtained from studies of Salmonella enterica serovar Typhimurium. However, these regulatory mechanisms do not apply to all bacterial groups. In this study, we have investigated regulation of the flagellar genetic system in Rhodobacter sphaeroi...

By gel retardation experiments with crude cell extracts of Paracoccus denitrificans it was demonstrated that a protein specifically binds to the promoter of the P. denitrificans recA gene. PCR mutagenesis of the recA promoter showed that the GAACN7GAAC motif is required for the formation of the DNA-protein complex. This protein also binds to the GTTCN7GTTC motif, which is present in the promote...

The light-harvesting apparatus of the purple bacterial photosynthetic unit consists of a pool of peripheral light-harvesting complexes that transfer excitation energy to a reaction center (RC) via the surrounding pigment-protein complex LH1. Recent electron microscopy and atomic force microscopy studies have revealed that RC-LH1 units of Rhodobacter sphaeroides form membrane-bending dimeric com...