Escherichia coli bacteria sensed the redox state in their surroundings and they swam to a niche that had a preferred reduction potential. In a spatial redox gradient of benzoquinone/benzoquinol, E. coli cells migrated to form a sharply defined band. Bacteria swimming out of either face of the band tumbled and returned to the preferred conditions at the site of the band. This behavioral response...

Activation of redox cascades through hydrogen peroxide-mediated reversible cysteine oxidation is a major mechanism for intracellular signaling. Understanding why some cysteine residues are specifically oxidized, in competition with other proximal cysteine residues and in the presence of strong redox buffers, is therefore crucial for understanding redox signaling. In this review, we explore the ...

Aerobic organisms generate reactive oxygen species as metabolic side products and must achieve a delicate balance between using them for signaling cellular functions and protecting against collateral damage. Small molecule (e.g. glutathione and cysteine)- and protein (e.g. thioredoxin)-based buffers regulate the ambient redox potentials in the various intracellular compartments, influence the s...

Aminophenols can redox cycle through the corresponding quinone imines to generate ROS. The electrophilic quinone imine intermediate can react with protein thiols as a mechanism of immobilization in vivo. Here, we describe the previously unkown transimination of a quinone imine by lysine as an alternative anchoring mechanism. The redox properties of the condensation product remain largely unchan...

The past decade has witnessed explosive development in the application of non-invasive spectroscopic techniques, and specifically of synchrotron-based EXAFS spectroscopy, to determine the local structure of poorly-crystallized solids, the crystal chemistry of substituted elements, and the sorption mechanism of metals in contact with the major contituants of soils and sediments (clays, Fe and Mn...

For many cytochromes P450 (P450), the electrons are transferred from the reductase to the P450 via a [2Fe-2S] cluster ferredoxin (e.g. putidaredoxin, terpredoxin or adrenodoxin). A similar role is played by several plant-type ferredoxins to transfer electrons from photosystem I to NADP. Other ferredoxins like E. coli ferredoxin are probably involved in the biogenesis of iron-sulfur clusters. To...

In photosynthesizing chloroplasts, rapidly changing energy input, intermediate generation of strong reductants as well as oxidants and multiple participating physicochemical processes and pathways, call for efficient regulation. Coupling redox information to protein function via thiol modifications offers a powerful mechanism to activate, down-regulate and coordinate interdependent processes. E...

We have discovered that intracellular redox state appears to be a necessary and sufficient modulator of the balance between self-renewal and differentiation in dividing oligodendrocyte-type-2 astrocyte progenitor cells. The intracellular redox state of freshly isolated progenitors allows prospective isolation of cells with different self-renewal characteristics. Redox state is itself modulated ...

Accumulation of reactive oxygen species (ROS) is one of the early defense responses against pathogen infection in plants. The mechanism about the initial and direct regulation of the defense signaling pathway by ROS remains elusive. Perturbation of cellular redox homeostasis by ROS is believed to alter functions of redox-sensitive proteins through their oxidative modifications. Here we report a...

Most flagellated green algae swim toward or away from the light source, i.e., display positive or negative phototaxis. Usually, the sign of phototaxis, positive or negative, is variable depending on various factors, but the mechanism that controls it has been unclear. Using Chlamydomonas reinhardtii, an excellent model organism for studying phototaxis, we have recently shown that cellular redox...