Special Issue "Physiological Sensors of Gases, Light, Redox State and Hypoxia"

Guest Editor
Prof. Dr. James D. Satterlee
Department of Chemistry, Washington State University, Pullman, WA 99164-4630, USA
Website: http://www.wsu.edu/~hemeteam/
E-Mail: hemeteam@wsu.edu
Phone: +1 509 335 8620
Fax: +1 509 335 8867
Interests: structure, function and dynamics of heme-enzyme small molecule sensors; PAS domain sensing and signaling proteins; globin-coupled sensor proteins; molecular engineering, NMR, X-ray crystallography, and mass spectrometry thereof

Dear Colleagues,

The past dozen years have witnessed increasing awareness of, and appreciation for the role played by protein biosensors in regulating physiological processes of organisms ranging from bacteria to mammals. It is the goal of this special issue of Biosensors to provide a forum focusing on recent research in several important areas in which naturally occurring protein biosensors control physiological processes. The scope of this issue encompasses physiological processes in any living organism. Specifically, this issue will preferentially focus on those biosensors that sense molecular gases, light, redox status and hypoxia. These broad topics will be defined by review articles targeting specific topics like NO-sensing, CO-sensing, O₂-Sensing, globin-coupled sensors, sensors of hypoxia, light sensing and redox sensing. It is expected that the review articles will provide succinct backgrounds and perhaps serve as fora for critical discussions of each topic. Submission of contributed manuscripts in any of these areas is enthusiastically encouraged. Original research articles are particularly welcome, but articles containing critical analyses of existing information are also acceptable.

Prof. Dr. James D. Satterlee
Guest Editor

Submission

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• light-sensing
• gas-sensing
• NO-sensing
• CO-sensing
• O₂-sensing
• redox-sensing
• hypoxia-sensing
• protein biosensors
• physiological sensors

Type of Paper: Review
Title: Heme-Regulated Phosphodiesterase (Ec DOS or DosP): Structure-Function Relationships, Gene Manipulation, and Application to Protein-Chip
Author: Toru Shimizu
Affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577, Japan; E-Mail: shimizu@tagen.tohoku.ac.jp
Abstract: Heme-regulated phosphodiesterase from Escherichia coli (Ec DOS or DosP) is a gas-sensor enzyme that catalyzes the conversion of cyclic-di-GMP to linear di-GMP, and its activity is markedly enhanced by O₂, CO or NO binding to the Fe(II) heme complex in the sensor domain. These characteristics induced by gas molecules are inconsistent with those of other well-known gas responsive heme sensor proteins, such as FixL, CooA, and soluble guanylate cyclase, which strictly recognize O₂, CO and NO, respectively, to regulate catalysis or transcription. Catalytic activity of the heme-free mutant, H77A, of Ec DOS was comparable to that of the gas-stimulated enzymes, suggesting that the heme at the sensor domain inhibits catalysis and that gas binding to the heme iron complex releases this catalytic suppression. In addition, the activities of the gas-free M95A and M95L mutants (Met95 serves as the axial ligand on the distal side of the Fe(II) heme-bound Ec DOS) were similar to that of the gas-activated wild-type enzyme. Thus, it is suggested that Met95 coordination to the Fe(II) heme is critical for locking the system and that global structural changes around Met95 caused by the binding of the external ligands or mutations at Met95 releases the catalytic lock and activates catalysis, as already been suggested from the X-ray crystal structural studies. Knocking down the Ec DOS gene in E. coli caused changes in cell growth rate, cell morphology, and intracellular cAMP concentration. Protein-protein interactions were suggested to be critical for the activity of Ec DOS, as demonstrated by the novel protein-chip using the antibody of Ec DOS. The review will summarize and discuss those and other intriguing findings obtained for Ec DOS.