Identification and Unusual Properties of the Master Regulator FNR in the Extreme Acidophile .

The ability to conserve energy in the presence or absence of oxygen provides a metabolic versatility that confers an advantage in natural ecosystems. The switch between alternative electron transport systems is controlled by the fumarate nitrate reduction transcription factor (FNR) that senses oxygen via an oxygen-sensitive [4Fe-4S] iron-sulfur cluster. Under O limiting conditions, FNR plays a key role in allowing bacteria to transition from aerobic to anaerobic lifestyles.

Effect of CO Concentration on Uptake and Assimilation of Inorganic Carbon in the Extreme Acidophile .

This study was motivated by surprising gaps in the current knowledge of microbial inorganic carbon (Ci) uptake and assimilation at acidic pH values (pH < 3). Particularly striking is the limited understanding of the differences between Ci uptake mechanisms in acidic versus circumneutral environments where the Ci predominantly occurs either as a dissolved gas (CO) or as bicarbonate (HCO ), respectively. In order to gain initial traction on the problem, the relative abundance of transcripts encoding proteins involved in Ci uptake and assimilation was studied in the autotrophic, polyextreme acidophile whose optimum pH for growth is 2.

Expression and activity of the Calvin-Benson-Bassham cycle transcriptional regulator CbbR from Acidithiobacillus ferrooxidans in Ralstonia eutropha.

Autotrophic fixation of carbon dioxide into cellular carbon occurs via several pathways but quantitatively, the Calvin-Benson-Bassham cycle is the most important. CbbR regulates the expression of the cbb genes involved in CO2 fixation via the Calvin-Benson-Bassham cycle in a number of autotrophic bacteria. A gene potentially encoding CbbR (cbbR(AF)) has been predicted in the genome of the chemolithoautotrophic, extreme acidophile Acidithiobacillus ferrooxidans.

α-fur, an antisense RNA gene to fur in the extreme acidophile Acidithiobacillus ferrooxidans.

A large non-coding RNA, termed α-Fur, of ~1000 nt has been detected in the extreme acidophile Acidithiobacillus ferrooxidans encoded on the antisense strand to the iron-responsive master regulator fur (ferric uptake regulator) gene. A promoter for α-fur was predicted bioinformatically and validated using gene fusion experiments. The promoter is situated within the coding region and in the same sense as proB, potentially encoding a glutamate 5-kinase.

An artifact in studies of gene regulation using β-galactosidase reporter gene assays.

Reporter gene assays are important tools for evaluating gene expression. A frequently used assay measures the activity of β-galactosidase (β-gal) expressed from lacZ in plasmid or genomic constructions. Such constructions are often used to interrogate the ability of DNA (query DNA), potentially encoding a transcription factor, to regulate in trans the expression of a promoter fused to the reporter lacZ.