The CarA/LitR-Family Transcriptional Regulator: Its Possible Role as a Photosensor and Wide Distribution in Non-Phototrophic Bacteria

Takano, Hideaki; Beppu, Teruhiko; Uéda, Kenji

doi:10.1271/bbb.60230

Cited by 18 publications

(24 citation statements)

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“…The first observation regarding the involvement of vitamin B 12 in the light-inducible carotenoid (Crt) production of the Gram-negative gliding bacterium Myxococcus xanthus was presented by Cervantes and Murillo (5). In nonphototrophic bacteria, the main function of Crt is to protect cells from photooxidative damage by scavenging harmful agents, such as singlet and triplet molecular species, produced upon illumination (6,7).…”

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“…The CoOC bond of AdoB 12 is chemically cleaved by light, which converts AdoB 12 to hydroxocobalamin (OHB 12 ). Therefore, light causes photolysis of AdoB 12 bound to CTt2, causing the conversion of AdoB 12 to OHB 12 , which abolishes its DNA-binding activity. The photolysis of AdoB 12 also induces a dramatic conformational change, i.e., subunit dissociation of CTt2 from a tetramer to a monomer.…”

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Role and Function of LitR, an Adenosyl B ₁₂ -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production

et al. 2015

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The LitR/CarH family of proteins is a light-sensitive MerR family of transcriptional regulators that contain an adenosyl B 12 (coenzyme B 12 or AdoB 12 )-binding domain at the C terminus. The genes encoding these proteins are found in phylogenetically diverse bacterial genera; however, the biochemical properties of these proteins from Gram-positive bacteria remain poorly understood. We performed genetic and biochemical analyses of a homolog of the LitR protein from Bacillus megaterium QM B1551, a Gram-positive endospore-forming soil bacterium. Carotenoid production was induced by illumination in this bacterium. In vivo analysis demonstrated that LitR plays a central role in light-inducible carotenoid production and serves as a negative regulator of the light-inducible transcription of crt and litR itself. Biochemical evidence showed that LitR in complex with AdoB 12 binds to the promoter regions of litR and the crt operon in a light-sensitive manner. In vitro transcription experiments demonstrated that AdoB 12 -LitR inhibited the specific transcription of the crt promoter generated by a A -containing RNA polymerase holoenzyme under dark conditions. Collectively, these data indicate that the AdoB 12 -LitR complex serves as a photoreceptor with DNA-binding activity in B. megaterium QM B1551 and that its function as a transcriptional repressor is fundamental to the light-induced carotenoid production. IMPORTANCEMembers of the LitR/CarH family are AdoB 12 -based photosensors involved in light-inducible carotenoid production in nonphototrophic Gram-negative bacteria. Our study revealed that Bacillus LitR in complex with AdoB 12 also serves as a transcriptional regulator with a photosensory function, which indicates that the LitR/CarH family is generally involved in the light-inducible carotenoid production of nonphototrophic bacteria.

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Role and Function of LitR, an Adenosyl B ₁₂ -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production

et al. 2015

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“…6,[18][19][20][21][22][23][24][25][26][27] These bacteria produce carotenoids -yellow, orange or red pigments -which protect them from photo-oxidative damage by quenching the singlet oxygen free radicals produced by absorption of energy from light. 19 The photoreceptor proteins were first discovered in the bacterium Myxococcus xanthus, 6,[18][19][20] which turns red in the presence of light, as a result of the synthesis of carotenoids, but is pale yellow in the dark.…”

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“…19 The photoreceptor proteins were first discovered in the bacterium Myxococcus xanthus, 6,[18][19][20] which turns red in the presence of light, as a result of the synthesis of carotenoids, but is pale yellow in the dark. However, carotenoids have also been found in a variety of other bacteria, including Streptomyces coelicolor [21][22][23] , Thermus thermophilus [24][25][26] and Bacillus megaterium 27 . Homologous sequences to the photoreceptor protein are found in the genomes of many bacteria and these proteins are probably widely distributed in non-photosynthetic bacteria.…”

Section: Introductionmentioning

confidence: 99%

“…Homologous sequences to the photoreceptor protein are found in the genomes of many bacteria and these proteins are probably widely distributed in non-photosynthetic bacteria. 6,17,19,22,25,26 The photoreceptor proteins were named CarH in M. xanthus 20 , TtCarH 25 or LitR 24 in T. thermophilus and LitR 27 in B. megaterium, but, for simplicity, and because the photoreceptor proteins are all very similar, in this review I shall use the designation CarH for the protein and carH for the gene.…”

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New light on vitamin B12: The adenosylcobalamin-dependent photoreceptor protein CarH

Chemaly¹

2016

S. Afr. J. Sci.

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Adenosylcobalamin (AdoCbl), or coenzyme B12, is a cofactor for enzymes important in metabolism in humans (and other mammals) and bacteria. AdoCbl contains a Co-C bond and is extremely light sensitive, but, until recently, this light sensitivity appeared to have no physiological function. Recently, AdoCbl has been found to act as cofactor for a photoreceptor protein (CarH) that controls the expression of DNA coding for transcription of the proteins needed for synthesis of carotenes in certain non-photosynthetic bacteria. In 2015, the X-ray crystal structures of two dark states of the photoreceptor protein from the bacterium Thermus thermophilus were determined: CarH bound to AdoCbl and CarH bound to a large portion of the cognate DNA operator (and AdoCbl); a light state was also determined in which CarH was bound to cobalamin in which the Co-C bond had been broken. The breaking of the Co-C bond of Ado-Cbl acts as a trigger for the regulatory switch that allows the transcription of DNA. In the two dark states AdoCbl is bound to a conserved histidine from CarH, which displaces the lower 5,6-dimethylbenzimidazole ligand of AdoCbl. In the light state the 5’-deoxyadenosyl group of AdoCbl is replaced by a second histidine from CarH, giving a bis-histidine cobalamin and 4’,5’-anhydroadenosine. Genes for B12-dependent photoreceptors are widespread in bacteria. Control of DNA transcription may represent an evolutionarily ancient function of AdoCbl, possibly pre-dating its function as a protein cofactor.

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Streptomyces metabolites in divergent microbial interactions

Takano

Nishiyama

Amano

et al. 2016

Journal of Industrial Microbiology and Biotechnology

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Streptomyces and related bacteria produce a wide variety of secondary metabolites. Of these, many compounds have industrial applications, but the question of why this group of microorganism produces such various kinds of biologically active substances has not yet been clearly answered. Here, we overview the results from our studies on the novel function and role of Streptomyces metabolites. The diverged action of negative and positive influences onto the physiology of various microorganisms infers the occurrence of complex microbial interactions due to the effect of small molecules produced by Streptomyces. The interactions may serve as a basis for the constitution of biological community.

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The CarA/LitR-Family Transcriptional Regulator: Its Possible Role as a Photosensor and Wide Distribution in Non-Phototrophic Bacteria

Cited by 18 publications

References 13 publications

Role and Function of LitR, an Adenosyl B ₁₂ -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production

Role and Function of LitR, an Adenosyl B ₁₂ -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production

New light on vitamin B12: The adenosylcobalamin-dependent photoreceptor protein CarH

Streptomyces metabolites in divergent microbial interactions

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The CarA/LitR-Family Transcriptional Regulator: Its Possible Role as a Photosensor and Wide Distribution in Non-Phototrophic Bacteria

Cited by 18 publications

References 13 publications

Role and Function of LitR, an Adenosyl B 12 -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production

Role and Function of LitR, an Adenosyl B 12 -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production

New light on vitamin B12: The adenosylcobalamin-dependent photoreceptor protein CarH

Streptomyces metabolites in divergent microbial interactions

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Role and Function of LitR, an Adenosyl B ₁₂ -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production

Role and Function of LitR, an Adenosyl B ₁₂ -Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production