Cytochrome d but not cytochrome o rescues the toluidine blue growth sensitivity of arc mutants of Escherichia coli.

Abstract	The Arc (anoxic redox control) two-component signal transduction system, consisting of the ArcB sensor kinase and the ArcA response regulator, allows adaptive responses of Escherichia coli to changes of O(2) availability. The arcA gene was previously known as the dye gene because null mutants were growth sensitive to the photosensitizer redox dyes toluidine blue and methylene blue, a phenotype whose molecular basis still remains elusive. In this study we report that the toluidine blue O (TBO) effect on the arc mutants is light independent and observed only during aerobic growth conditions. Moreover, 16 suppressor mutants with restored growth were generated and analyzed. Thirteen of those possessed insertion elements upstream of the cydAB operon, rendering its expression ArcA independent. Also, it was found that, in contrast to cythocrome d, cythocrome o was not able to confer toluidine blue resistance to arc mutants, thereby representing an intriguing difference between the two terminal oxidases. Finally, a mechanism for TBO sensitivity and resistance is discussed.
Authors	Adrian F Alvarez, Roxana Malpica, Martha Contreras, Edgardo Escamilla, Dimitris Georgellis
Journal	Journal of bacteriology (J Bacteriol) Vol. 192 Issue 2 Pg. 391-9 (Jan 2010) ISSN: 1098-5530 [Electronic] United States
PMID	19897650 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References	Bacterial Outer Membrane Proteins Coloring Agents Cytochrome b Group Cytochromes Electron Transport Chain Complex Proteins Escherichia coli Proteins Reactive Oxygen Species Repressor Proteins arcA protein, E coli Tolonium Chloride Carotenoids Cytochrome d Group cytochrome bo, E coli Oxidoreductases Catalase Superoxide Dismutase cytochrome bd terminal oxidase complex, E coli Glucose
Topics	Anaerobiosis Bacterial Outer Membrane Proteins (genetics, metabolism) Base Sequence Carotenoids (metabolism) Catalase (metabolism) Coloring Agents (pharmacology) Cytochrome b Group (genetics, metabolism) Cytochrome d Group (genetics, metabolism) Cytochromes (genetics, metabolism) Darkness Electron Transport Chain Complex Proteins (genetics) Escherichia coli (drug effects, genetics, growth & development, metabolism) Escherichia coli Proteins (genetics, metabolism) Gene Expression Regulation, Bacterial (drug effects, genetics, radiation effects) Glucose (pharmacology) Light Molecular Sequence Data Mutation (genetics) Oxidoreductases (genetics) Promoter Regions, Genetic (genetics) Reactive Oxygen Species (metabolism) Repressor Proteins (genetics, metabolism) Sequence Homology, Nucleic Acid Superoxide Dismutase (metabolism) Tolonium Chloride (pharmacology)

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