Gene cloning and regulation of gene expression of the puc operon from Rhodovulum sulfidophilum

Hagemann, Gesine E.; Katsiou, Eleni; Forkl, Hubert; Steindorf, Astrid; Tadros, Monier H.

doi:10.1016/s0167-4781(96)00228-x

Cited by 20 publications

(14 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A small amount of LH2 a1 was found to have five residues removed from C-terminus. Similar C-terminal processing was also observed for the LH2 a-polypeptides from other purple bacteria (Hagemann et al 1997). Part of the a1-polypeptide appeared to be oxidized, probably at the Met residue in the N-terminal domain as this is the sole Met in the a1-polypeptide.…”

Section: Discussionsupporting

confidence: 70%

Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum

et al. 2011

View full text Add to dashboard Cite

In this study, gene sequences coding for the light-harvesting (LH) 2 polypeptides from a thermophilic purple sulfur bacterium Thermochromatium tepidum are reported and characterization of the LH2 complex is described. Three sets of pucBA genes have been identified, and the gene products have been analyzed by electrophoresis and reversed-phase chromatography. The result shows that all of the genes are expressed but the distribution of the expression is not uniform. The gene products undergo post-translational modification, where two of the β-polypeptides appear to be N-terminally methylated. Absorption spectrum of the purified LH2 complex exhibits Q (y) transitions at 800 and 854 nm in dodecyl β-maltopyranoside solution, and the circular dichroism spectrum shows a "molischianum"-like characteristic. No spectral change was observed for the LH2 when the bacterium was cultured under different conditions of light intensity. In lauryl dimethylamine N-oxide (LDAO) solution, significant changes in the absorption spectrum were observed. The B850 peak decreased and blue-shifted with increasing the LDAO concentration, whereas the B800 intensity increased without change in the peak position. The spectral changes can be partially or almost completely reversed by addition of metal ions, and the divalent cations seem to be more effective. The results indicate that ionic interactions may exist between LH2, detergent molecules and metal ions. Possible mechanisms involved in the detergent- and cation-induced spectral changes are discussed.

show abstract

Section: Discussionsupporting

confidence: 70%

Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum

et al. 2011

View full text Add to dashboard Cite

show abstract

“…The response to oxygen of R. depolymerans under aerobic and semiaerobic conditions may be understood similarly to those of R. sulfidophilum and R. centenum. However, R. depolymerans does not grow on light anaerobically, and the responses to oxygen of this organism (Fig 2d) and the two phototrophic species are not wholly alike (11,21,40). As shown by the response to oxygen, R. depolymerans is a unique organism containing BChl a which is distinguishable from both phototrophic and aerobic phototrophic bacteria studied so far.…”

Section: Discussionmentioning

confidence: 87%

“…This finding suggests that the R. depolymerans puf operon is regulated by oxygen tension differently from that of R. denitrificans (24). Two phototrophic species of ␣-Proteobacteria, Rhodovulum sulfidophilum (11,21) and Rhodospirillum centenum (40), are known to produce a photosynthetic apparatus under aerobic conditions, due to their weak repression of photosystem synthesis. The response to oxygen of R. depolymerans under aerobic and semiaerobic conditions may be understood similarly to those of R. sulfidophilum and R. centenum.…”

Section: Discussionmentioning

confidence: 99%

Photosynthetic Apparatus in Roseateles depolymerans 61A Is Transcriptionally Induced by Carbon Limitation

Suyama

Shigematsu

Suzuki

et al. 2002

Appl Environ Microbiol

View full text Add to dashboard Cite

Production of a photosynthetic apparatus in Roseateles depolymerans 61A, a recently discovered freshwater ␤-Proteobacterium showing characteristics of aerobic phototrophic bacteria, was observed when the cells were subjected to a sudden decrease in carbon sources (e.g., when cells grown with 0.1 to 0.4% Casamino Acids were diluted or transferred into medium containing <0.04% Casamino Acids). Accumulation of bacteriochlorophyll (BChl) a was observed in the presence of oxygen and was enhanced under semiaerobic conditions (2% oxygen) but was reduced in the presence of light. Similarly to what has been reported regarding some aerobic phototrophic bacteria belonging to the ␣ subclass of the Proteobacteria, viability of the cells in the carbon source-free medium was prolonged under aerobic-light (10 W m ؊2 ) conditions, possibly due to photosynthetic energy conversion, but was not prolonged under aerobic-dark conditions. The puf operon, which encodes most of the apoproteins of light-harvesting and reaction center complexes, was sequenced, and the effect of changes in Casamino Acids concentrations, oxygen, and light on its expression was estimated by the accumulation of its mRNA. The expression of the puf operon was induced by the decrease in carbon sources, similarly to what was observed for the accumulation of BChl a under aerobic and semiaerobic conditions (>0.2% O 2 ), and was reduced in the presence of light. Transcription of the R. depolymerans puf operon is considered to be controlled by changes in carbon nutrients in addition to oxygen tension and light intensity.Purple phototrophic bacteria are taxonomically affiliated with the ␣, ␤, and ␥ subclasses of the class Proteobacteria. Many of the species grow both heterotrophically under aerobic-dark conditions and phototrophically under anaerobic-light conditions. The production of a photosynthetic apparatus in most of these phototrophic species is reduced under aerobic conditions (18). On the other hand, some species, the so-called aerobic phototrophic bacteria (e.g., Erythrobacter longus and Roseobacter denitrificans), do not grow phototrophically under anaerobic-light conditions, whereas they produce a photosynthetic apparatus under aerobic conditions (31, 41). Aerobic phototrophic bacteria had been reported only for the ␣ subclass of the Proteobacteria (31, 41) until the discovery of Roseateles depolymerans, which belongs to the ␤ subclass of the Proteobacteria (34).Although the presence of photochemical activity has been clarified in some species of aerobic phototrophic bacteria, they do not grow on light as a sole energy source (14,31,36,38). However, stimulation of growth in the presence of light has been reported for R. denitrificans, Erythromicrobium hydrolyticum, and Acidisphaera rubrifaciens (13,15,42). It has also been suggested for R. denitrificans, Bradyrhizobium strain BTAi 1, and A. rubrifaciens that the preservation of viability is improved by the presence of light in the absence of nutrients (9,15,29). While these observations have been reported f...

show abstract

“…In contrast to Rhodobacter species, R. sulfidophilum synthesizes the photosynthetic apparatus even under highly aerated conditions in the dark (14). A study of the puc operon of R. sulfidophilum showed that puc mRNA synthesis is weakly repressed by oxygen but markedly suppressed by highintensity light (19). This is distinctly different from the results shown for the Rhodobacter species, which show a high degree of repression by oxygen and a weak repression by light (2,3).…”

mentioning

confidence: 66%

Transcriptional Control of Expression of Genes for Photosynthetic Reaction Center and Light-Harvesting Proteins in the Purple Bacterium Rhodovulum sulfidophilum

et al. 2000

View full text Add to dashboard Cite

The purple photosynthetic bacterium Rhodovulum sulfidophilum synthesizes photosynthetic apparatus even under highly aerated conditions in the dark. To understand the oxygen-independent expression of photosynthetic genes, the expression of the puf operon coding for the light-harvesting 1 and reaction center proteins was analyzed. Northern blot hybridization analysis showed that puf mRNA synthesis was not significantly repressed by oxygen in this bacterium. High-resolution 5 mapping of the puf mRNA transcriptional initiation sites and DNA sequence analysis of the puf upstream regulatory region indicated that there are three possible promoters for the puf operon expression, two of which have a high degree of sequence similarity with those of Rhodobacter capsulatus, which shows a high level of oxygen repression of photosystem synthesis. Deletion analysis showed that the third promoter is oxygen independent, but the activity of this promoter was not enough to explain the aerobic level of mRNA. The posttranscriptional puf mRNA degradation is not significantly influenced by oxygen in R. sulfidophilum. From these results, we conclude that puf operon expression in R. sulfidophilum is weakly repressed by oxygen, perhaps as a result of the following: (i) there are three promoters for puf operon transcription, at least one of which is oxygen independent; (ii) readthrough transcripts which may not be affected by oxygen may be significant in maintaining the puf mRNA levels; and (iii) the puf mRNA is fairly stable even under aerobic conditions.The purple photosynthetic bacterium Rhodovulum sulfidophilum is a marine bacterium that can grow by either photosynthesis or respiration on a wide range of organic compounds (20). Like those of other purple bacteria, the photosynthetic apparatus of R. sulfidophilum is composed of three membrane-spanning pigment protein complexes known as the reaction center (RC) and the light-harvesting 1 and 2 complexes (LH1 and LH2, respectively). The light energy captured by LH1 and LH2 is transferred to the RC, where the primary photochemical reaction takes place. The RC complexes of most purple bacteria are known to consist of at least L, M, and H subunits. The light-harvesting complexes are composed of two membrane-spanning polypeptides, ␣ and ␤ subunits, which bind bacteriochlorophylls (BChls) and carotenoids (13,15,48). It is known that these proteins are encoded by three operons: the puf operon, which encodes the LH1 ␣ and ␤ polypeptides and the RC-L and -M polypeptides; the puc operon, which encodes the LH2 ␣ and ␤ polypeptides; and the puh operon, which encodes RC-H polypeptide (9,26,44,46,47). Some purple bacteria have a pufC gene in the puf operon that encodes an RC-bound cytochrome subunit with four ctype hemes. Recently, we sequenced the whole puf operon of R. sulfidophilum and showed that this bacterium has a pufC gene in the puf operon encoding a unique cytochrome subunit that contains only three possible heme-binding sites (30).In some purple bacteria such as Rhodobacter species, the sy...

show abstract

Gene cloning and regulation of gene expression of the puc operon from Rhodovulum sulfidophilum

Cited by 20 publications

References 42 publications

Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum

Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum

Photosynthetic Apparatus in Roseateles depolymerans 61A Is Transcriptionally Induced by Carbon Limitation

Transcriptional Control of Expression of Genes for Photosynthetic Reaction Center and Light-Harvesting Proteins in the Purple Bacterium Rhodovulum sulfidophilum

Contact Info

Product

Resources

About