Photosensing in chemotrophic, non-phototrophic bacteria: let there be light sensing too

Horst, Michael; Key, Jason; Hellingwerf, Klaas J.

doi:10.1016/j.tim.2007.09.009

Cited by 129 publications

(123 citation statements)

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“…Known photoreceptor proteins are typically of a modular design, with light-sensing entrusted to an independent domain (14-16). As a result, the light-sensing input module can be found linked to various types of effector or output domains for use in diverse processes (14)(15)(16). Our finding that B 12 -dependent photosensing is also housed in a single, autonomous module suggests that, other than in MerR-type DNA-binding factors or conventional B 12 -dependent enzymes, it may also occur in association with other effector domains.…”

Section: Discussionmentioning

confidence: 83%

“…As a consequence, repressor oligomers are disassembled and operator binding is impaired. AdoB 12 is therefore one more in the list of chromophores such as flavin mononucleotide, flavin adenine dinucleotide, retinal, p-coumaric acid, and linear tetrapyrroles (bilins and biliverdins) that confer light sensing ability to photoactive proteins (14)(15)(16). The predominant trigger for carotenogenesis in M. xanthus is blue light, as this alone can activate the carQRS operon (via the distinct protoporphyrin IX-mediated pathway) to produce CarS and neutralize P B repression by CarA and CarH (13).…”

Section: Discussionmentioning

confidence: 99%

“…Cells usually sense light, a key environmental factor, via photoreceptor proteins containing small-molecule chromophores, and six such photoreceptor families have been cataloged in bacteria (14)(15)(16). However, none of these have been implicated in M. xanthus light-induced carotenogenesis, in which available data suggest that light is sensed by a photosensitizer molecule, protoporphyrin IX, rather than by a dedicated photoreceptor protein (13,17).…”

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confidence: 99%

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Light-dependent gene regulation by a coenzyme B ₁₂ -based photoreceptor

Ortiz-Guerrero

Polanco

Murillo

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

154

247

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Cobalamin (B 12 ) typically functions as an enzyme cofactor but can also regulate gene expression via RNA-based riboswitches. B 12 -directed gene regulatory mechanisms via protein factors have, however, remained elusive. Recently, we reported down-regulation of a light-inducible promoter in the bacterium Myxococcus xanthus by two paralogous transcriptional repressors, of which one, CarH, but not the other, CarA, absolutely requires B 12 for activity even though both have a canonical B 12 -binding motif. Unanswered were what underlies this striking difference, what is the specific cobalamin used, and how it acts. Here, we show that coenzyme B 12 (5′-deoxyadenosylcobalamin, AdoB 12 ), specifically dictates CarH function in the dark and on exposure to light. In the dark, AdoB 12 -binding to the autonomous domain containing the B 12 -binding motif foments repressor oligomerization, enhances operator binding, and blocks transcription. Light, at various wavelengths at which AdoB 12 absorbs, dismantles active repressor oligomers by photolysing the bound AdoB 12 and weakens repressor-operator binding to allow transcription. By contrast, AdoB 12 alters neither CarA oligomerization nor operator binding, thus accounting for its B 12 -independent activity. Our findings unveil a functional facet of AdoB 12 whereby it serves as the chromophore of a unique photoreceptor protein class acting in light-dependent gene regulation. The prevalence of similar proteins of unknown function in microbial genomes suggests that this distinct B 12 -based molecular mechanism for photoregulation may be widespread in bacteria.carotenogenesis | Thermus thermophilus | antirepressor | MerR | TtCarH

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Light-dependent gene regulation by a coenzyme B ₁₂ -based photoreceptor

Ortiz-Guerrero

Polanco

Murillo

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

154

247

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“…For example, recently a set of chromophores was discovered in non-phototrophic bacteria [56], which are able to act as gene transcription factors. Those proteins fulfill all the requisitions for receiver molecules.…”

Section: The Receiversmentioning

confidence: 99%

“…-The BLUF domain responds to blue light: the peaks are at 375 and 450 nm [56] and other wavelengths [49]. -The PYP domain can respond to 446, 358, 434, and 465 nm depending on the cellular state [56,67].…”

Section: The Compliancementioning

confidence: 99%

Light based cellular interactions: hypotheses and perspectives

Laager¹

2015

Front. Phys.

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This work investigates the theoretical possibility of interactions between cells via light. We first take a brief look at the previous research done in the past to have a better understanding of the field and the origins of the concept of cellular interactions. Then we identify the different elements essential for interactions between two parties. We then compare the required elements with the known and studied elements and characteristics which are well defined in biology, chemistry and physics. This way we are able to set up four postulates required for cell interactions: I. A signal is present and subject to secondary modulation by the emitter cells. II. There is a plastic information medium that reacts directly to the metabolic state of the emitter and therefore carries information about the emitter. III. An optical signal can be perceived by cells on a molecular level by a multitude of different receptors. IV. The information can in theory be processed by cells and metabolic changes in reaction to the signals can be observed. We demonstrate that all required elements have been observed. Most of them have important and well-known roles in cells. Therefore, we suggest that our hypothetical model is a good explanation for light based cellular interactions.

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Changes in Active Site Hydrogen Bonding upon Formation of the Electronically Excited State of Photoactive Yellow Protein

Hoff

Kang

Kumauchi

et al. 2010

Hydrogen Bonding and Transfer in the Excited State

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Light plays three main roles in biology. First, light from the sun provides the main source of energy driving the biosphere through chlorophyll-based electron transfer in photosynthetic reaction centers and retinal-based proton pumping in rhodopsins [1]. Second, light is a source of information about the environment for many organisms using photosensory proteins, including animals, plants, fungi and bacteria [2,3]. Third, light can cause damage to biological systems. Light from the near-UV region can damage DNA [4], and excess visible light can damage the photosynthetic machinery in photoinhibition [5]. Thus, light is of great importance for a wide range of biological processes.Proteins that perform photosynthesis or light sensing consist of an apoprotein and a bound chromophore. Only a small number of chromophores account for most known processes in photobiology: chlorophyll and linear tetrapyrroles, caretoids and retinal, flavins and p-coumaric acid [2]. In many cases the chromophore has strong and functionally important interactions with the protein binding pocket, particularly charge-charge interactions and hydrogen bonding interactions. While many different proteins interact with light in a wide range of organisms, almost all of these systems are based on key types of photochemical processes, including electron transfer, C¼C double bond isomerization and the formation of chemical bonds [2,6]. These photochemical events often trigger a cascade of thermal reactions in the protein that extends to the millisecond and minute range, and that result in a biologically relevant output. If the cascade of thermal reactions results in the re-formation of the initial state, the process is referred to as a photocycle. It is the initial ultrafast

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Photosensing in chemotrophic, non-phototrophic bacteria: let there be light sensing too

Cited by 129 publications

References 50 publications

Light-dependent gene regulation by a coenzyme B ₁₂ -based photoreceptor

Light-dependent gene regulation by a coenzyme B ₁₂ -based photoreceptor

Light based cellular interactions: hypotheses and perspectives

Changes in Active Site Hydrogen Bonding upon Formation of the Electronically Excited State of Photoactive Yellow Protein

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Photosensing in chemotrophic, non-phototrophic bacteria: let there be light sensing too

Cited by 129 publications

References 50 publications

Light-dependent gene regulation by a coenzyme B 12 -based photoreceptor

Light-dependent gene regulation by a coenzyme B 12 -based photoreceptor

Light based cellular interactions: hypotheses and perspectives

Changes in Active Site Hydrogen Bonding upon Formation of the Electronically Excited State of Photoactive Yellow Protein

Contact Info

Product

Resources

About

Light-dependent gene regulation by a coenzyme B ₁₂ -based photoreceptor

Light-dependent gene regulation by a coenzyme B ₁₂ -based photoreceptor