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Marques HM. The inorganic chemistry of the cobalt corrinoids - an update. J Inorg Biochem 2023; 242:112154. [PMID: 36871417 DOI: 10.1016/j.jinorgbio.2023.112154] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 01/23/2023] [Accepted: 01/26/2023] [Indexed: 02/05/2023]
Abstract
The inorganic chemistry of the cobalt corrinoids, derivatives of vitamin B12, is reviewed, with particular emphasis on equilibrium constants for, and kinetics of, their axial ligand substitution reactions. The role the corrin ligand plays in controlling and modifying the properties of the metal ion is emphasised. Other aspects of the chemistry of these compounds, including their structure, corrinoid complexes with metals other than cobalt, the redox chemistry of the cobalt corrinoids and their chemical redox reactions, and their photochemistry are discussed. Their role as catalysts in non-biological reactions and aspects of their organometallic chemistry are briefly mentioned. Particular mention is made of the role that computational methods - and especially DFT calculations - have played in developing our understanding of the inorganic chemistry of these compounds. A brief overview of the biological chemistry of the B12-dependent enzymes is also given for the reader's convenience.
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Affiliation(s)
- Helder M Marques
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa.
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2
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Role and Function of Class III LitR, a Photosensor Homolog from Burkholderia multivorans. J Bacteriol 2018; 200:JB.00285-18. [PMID: 30249707 DOI: 10.1128/jb.00285-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 09/13/2018] [Indexed: 11/20/2022] Open
Abstract
The LitR/CarH protein family is an adenosyl B12 (AdoB12)-dependent photoreceptor family with DNA-binding activity, and its homologs are widely distributed in the genomes of diverse bacterial genera. In this investigation, we studied the role and functions of a LitR homolog from a Gram-negative soil bacterium, Burkholderia multivorans, which does not possess an AdoB12-binding domain. Transcriptome analysis indicated the existence of 19 light-induced genes, including folE2, cfaB, litS, photolyase gene phrB2, and cryB, located in the region flanking litR Disruption of litR caused constitutive expression of all the light-inducible genes, while mutation in the light-induced sigma factor gene, litS, abolished the transcription of the phrB2 operon and the cfa operon, indicating that LitR and LitS play a central role in light-inducible transcription. A gel shift assay showed that recombinant protein LitR specifically binds to the promoter regions of litR and the folE2 operon, and its binding was weakened by UV-A illumination. LitR absorbs light at maximally near 340 nm and exhibited a photocyclic response and light-dependent dissociation of multimer into tetramer. The litR mutant produced a 20-fold-higher intracellular level of folate than that of the wild-type strain. Thus, the evidence suggests that LitR light-dependently regulates the transcription of litR itself and the folE2 operon, resulting in the production of folate, and then the expressed RNA polymerase complex containing σLitS directs the transcription of the phrB2 operon and the cfa operon. These light-dependent characteristics suggest that class III LitR, in complex with a UV-A-absorbing molecule, follows a novel light-sensing mechanism.IMPORTANCE Members of the LitR/CarH family are adenosyl B12-based photosensory transcriptional regulator involved in light-inducible carotenoid production in nonphototrophic bacteria. Our study provides the first evidence of the involvement of a class III LitR, which lacks an adenosyl B12-binding domain in the light response of Burkholderia multivorans belonging to betaproteobacteria. Our biochemical analysis suggests that class III LitR protein exhibits features as a photosensor including absorption of light at the UV-A region (λmax = ca. 340 nm), photocyclic response, and light-dependent dissociation. This suggests that class III LitR associates with a UV-A-absorbing molecule, and it has a photosensing mechanism distinguishable from that of the B12-based type.
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Tardu M, Bulut S, Kavakli IH. MerR and ChrR mediate blue light induced photo-oxidative stress response at the transcriptional level in Vibrio cholerae. Sci Rep 2017; 7:40817. [PMID: 28098242 PMCID: PMC5241685 DOI: 10.1038/srep40817] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/09/2016] [Indexed: 12/14/2022] Open
Abstract
Blue light (BL) is a major environmental factor that affects the physiology, behavior, and infectivity of bacteria as it contributes to the generation of reactive oxygen species (ROS) while increasing photo-oxidative stress in cells. However, precise photo-oxidative response mechanism in non-phototrophic bacteria is yet to be elucidated. In this study, we investigated the effect of BL in Vibrio cholerae by using genetics and transcriptome profiling. Genome-wide analysis revealed that transcription of 6.3% of V. cholerae genes were regulated by BL. We further showed that BL enhances ROS production, which is generated through the oxidative phosphorylation. To understand signaling mechanisms, we generated several knockouts and analyzed their transcriptome under BL exposure. Studies with a double-knockout confirm an anti-sigma factor (ChrR) and putative metalloregulatory-like protein (MerR) are responsible for the genome-wide regulation to BL response in V. cholerae. Collectively, these results demonstrate that MerR-like proteins, in addition to ChrR, are required for V. cholerae to mount an appropriate response against photo-oxidative stress induced by BL. Outside its natural host, V. cholerae can survive for extended periods in natural aquatic environments. Therefore, the regulation of light response for V. cholerae may be a critical cellular process for its survival in these environments.
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Affiliation(s)
- Mehmet Tardu
- Computational Science and Engineering, Koc University, Rumeli Feneri Yolu, Sariyer, Istanbul, Turkey
| | - Selma Bulut
- Chemical and Biological Engineering, Koc University, Rumeli Feneri Yolu, Sariyer, Istanbul, Turkey
| | - Ibrahim Halil Kavakli
- Computational Science and Engineering, Koc University, Rumeli Feneri Yolu, Sariyer, Istanbul, Turkey.,Chemical and Biological Engineering, Koc University, Rumeli Feneri Yolu, Sariyer, Istanbul, Turkey.,Molecular Biology and Genetics, Koc University, Rumeli Feneri Yolu, Sariyer, Istanbul, Turkey
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4
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Takano H, Mise K, Maruyama T, Hagiwara K, Ueda K. Role of the semi-conserved histidine residue in the light-sensing domain of LitR, a MerR-type photosensory transcriptional regulator. MICROBIOLOGY-SGM 2016; 162:1500-1509. [PMID: 27283316 DOI: 10.1099/mic.0.000321] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The LitR/CarH protein family transcriptional regulator is a new type of photoreceptor based on the function of adenosyl B12 (AdoB12) as a light-sensitive ligand. Here, we studied a semi-conserved histidine residue (His132) in the light-sensing (AdoB12-binding) domain at the C-terminus of LitR from a thermophilic Gram-negative bacterium, Thermus thermophilus HB27. The in vivo mutation of His132 within LitR caused a reduction in the rate of carotenoid production in response to illumination. BIAcore analysis revealed that the illuminated-LitRH132A possesses high DNA-binding activity compared to the wild-type protein. The subunit structure analysis showed that LitRH132A performed an incomplete subunit dissociation. The ability of LitRH132A to associate with AdoB12 was reduced compared with that of the wild-type protein in an equilibration dialysis experiment. Overall, these results suggest that His132 of LitR is involved in the association with AdoB12 as well as the light-sensitive DNA-binding activity based on oligomer dissociation.
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Affiliation(s)
- Hideaki Takano
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan
| | - Kou Mise
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan
| | - Takafumi Maruyama
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan
| | - Kenta Hagiwara
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan
| | - Kenji Ueda
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa 252-0880, Japan
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Ferrer A, Rivera J, Zapata C, Norambuena J, Sandoval Á, Chávez R, Orellana O, Levicán G. Cobalamin Protection against Oxidative Stress in the Acidophilic Iron-oxidizing Bacterium Leptospirillum Group II CF-1. Front Microbiol 2016; 7:748. [PMID: 27242761 PMCID: PMC4876134 DOI: 10.3389/fmicb.2016.00748] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/03/2016] [Indexed: 11/30/2022] Open
Abstract
Members of the genus Leptospirillum are aerobic iron-oxidizing bacteria belonging to the phylum Nitrospira. They are important members of microbial communities that catalyze the biomining of sulfidic ores, thereby solubilizing metal ions. These microorganisms live under extremely acidic and metal-loaded environments and thus must tolerate high concentrations of reactive oxygen species (ROS). Cobalamin (vitamin B12) is a cobalt-containing tetrapyrrole cofactor involved in intramolecular rearrangement reactions and has recently been suggested to be an intracellular antioxidant. In this work, we investigated the effect of the exogenous addition of cobalamin on oxidative stress parameters in Leptospirillum group II strain CF-1. Our results revealed that the external supplementation of cobalamin reduces the levels of intracellular ROSs and the damage to biomolecules, and also stimulates the growth and survival of cells exposed to oxidative stress exerted by ferric ion, hydrogen peroxide, chromate and diamide. Furthermore, exposure of strain CF-1 to oxidative stress elicitors resulted in the transcriptional activation of the cbiA gene encoding CbiA of the cobalamin biosynthetic pathway. Altogether, these data suggest that cobalamin plays an important role in redox protection of Leptospirillum strain CF-1, supporting survival of this microorganism under extremely oxidative environmental conditions. Understanding the mechanisms underlying the protective effect of cobalamin against oxidative stress may help to develop strategies to make biomining processes more effective.
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Affiliation(s)
- Alonso Ferrer
- Laboratory of Basic an Applied Microbiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago Santiago, Chile
| | - Javier Rivera
- Laboratory of Basic an Applied Microbiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago Santiago, Chile
| | - Claudia Zapata
- Laboratory of Basic an Applied Microbiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago Santiago, Chile
| | - Javiera Norambuena
- Laboratory of Basic an Applied Microbiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago Santiago, Chile
| | - Álvaro Sandoval
- Laboratory of Basic an Applied Microbiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago Santiago, Chile
| | - Renato Chávez
- Laboratory of Basic an Applied Microbiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago Santiago, Chile
| | - Omar Orellana
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile Santiago, Chile
| | - Gloria Levicán
- Laboratory of Basic an Applied Microbiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago Santiago, Chile
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6
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Takano H. The regulatory mechanism underlying light-inducible production of carotenoids in nonphototrophic bacteria. Biosci Biotechnol Biochem 2016; 80:1264-73. [PMID: 26967471 DOI: 10.1080/09168451.2016.1156478] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Light is a ubiquitous environmental factor serving as an energy source and external stimulus. Here, I review the conserved molecular mechanism of light-inducible production of carotenoids in three nonphototrophic bacteria: Streptomyces coelicolor A3(2), Thermus thermophilus HB27, and Bacillus megaterium QM B1551. A MerR family transcriptional regulator, LitR, commonly plays a central role in their light-inducible carotenoid production. Genetic and biochemical studies on LitR proteins revealed a conserved function: LitR in complex with adenosyl B12 (AdoB12) has a light-sensitive DNA-binding activity and thus suppresses the expression of the Crt biosynthesis gene cluster. The in vitro DNA-binding and transcription assays showed that the LitR-AdoB12 complex serves as a repressor allowing transcription initiation by RNA polymerase in response to illumination. The existence of novel light-inducible genes and the unique role of the megaplasmid were revealed by the transcriptomic analysis of T. thermophilus. The findings suggest that LitR is a general regulator responsible for the light-inducible carotenoid production in the phylogenetically divergent nonphototrophic bacteria, and that LitR performs diverse physiological functions in bacteria.
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Affiliation(s)
- Hideaki Takano
- a Applied Biological Science and Life Science Research Center, College of Bioresource Sciences , Nihon University , Fujisawa , Japan
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7
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Streptomyces metabolites in divergent microbial interactions. ACTA ACUST UNITED AC 2016; 43:143-8. [DOI: 10.1007/s10295-015-1680-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 08/27/2015] [Indexed: 12/11/2022]
Abstract
Abstract
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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Role and Function of LitR, an Adenosyl B12-Bound Light-Sensitive Regulator of Bacillus megaterium QM B1551, in Regulation of Carotenoid Production. J Bacteriol 2015; 197:2301-15. [PMID: 25917914 DOI: 10.1128/jb.02528-14] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/23/2015] [Indexed: 12/25/2022] Open
Abstract
UNLABELLED The LitR/CarH family of proteins is a light-sensitive MerR family of transcriptional regulators that contain an adenosyl B12 (coenzyme B12 or AdoB12)-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 AdoB12 binds to the promoter regions of litR and the crt operon in a light-sensitive manner. In vitro transcription experiments demonstrated that AdoB12-LitR inhibited the specific transcription of the crt promoter generated by a σ(A)-containing RNA polymerase holoenzyme under dark conditions. Collectively, these data indicate that the AdoB12-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. IMPORTANCE Members of the LitR/CarH family are AdoB12-based photosensors involved in light-inducible carotenoid production in nonphototrophic Gram-negative bacteria. Our study revealed that Bacillus LitR in complex with AdoB12 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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Takano H, Agari Y, Hagiwara K, Watanabe R, Yamazaki R, Beppu T, Shinkai A, Ueda K. LdrP, a cAMP receptor protein/FNR family transcriptional regulator, serves as a positive regulator for the light-inducible gene cluster in the megaplasmid of Thermus thermophilus. Microbiology (Reading) 2014; 160:2650-2660. [DOI: 10.1099/mic.0.082263-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
LdrP (TT_P0055) (LitR-dependent regulatory protein) is one of the four cAMP receptor protein (CRP)/FNR family transcriptional regulators retained by the extremely thermophilic bacterium Thermus thermophilus. Previously, we reported that LdrP served as a positive regulator for the light-induced transcription of crtB, a carotenoid biosynthesis gene encoded on the megaplasmid of this organism. Here, we showed that LdrP also functions as an activator of the expression of genes clustered around the crtB gene under the control of LitR, an adenosyl B12-bound light-sensitive regulator. Transcriptome analysis revealed the existence of 19 LitR-dependent genes on the megaplasmid. S1 nuclease protection assay confirmed that the promoters preceding TT_P0044 (P44), TT_P0049 (P49) and TT_P0070 (P70) were activated upon illumination in the WT strain. An ldrP mutant lost the ability to activate P44, P49 and P70, whilst disruption of litR resulted in constitutive transcription from these promoters irrespective of illumination, indicating that these genes were photo-dependently regulated by LdrP and LitR. An in vitro transcription experiment demonstrated that LdrP directly activated mRNA synthesis from P44 and P70 by the Thermus RNA polymerase holocomplex. The present evidence indicated that LdrP was the positive regulator essential for the transcription of the T. thermophilus light-inducible cluster encoded on the megaplasmid.
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Affiliation(s)
- Hideaki Takano
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan
| | - Yoshihiro Agari
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Kenta Hagiwara
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan
| | - Ren Watanabe
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan
| | - Ryuta Yamazaki
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan
| | - Teruhiko Beppu
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan
| | - Akeo Shinkai
- RIKEN Structural Biology Laboratory, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Kenji Ueda
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan
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Involvement of CarA/LitR and CRP/FNR family transcriptional regulators in light-induced carotenoid production in Thermus thermophilus. J Bacteriol 2011; 193:2451-9. [PMID: 21421762 DOI: 10.1128/jb.01125-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of the CarA/LitR family are MerR-type transcriptional regulators that contain a C-terminal cobalamin-binding domain. They are thought to be involved in light-induced transcriptional regulation in a wide variety of nonphototrophic bacteria. Based on the distribution of this kind of regulator, the current study examined carotenoid production in Thermus thermophilus, and it was found to occur in a light-induced manner. litR and carotenoid and cobalamin biosynthesis genes were all located on the large plasmid of this organism. litR or cobalamin biosynthesis gene knockout mutants were unable to switch off carotenoid production under dark conditions, while a mutant with a mutation in the downstream gene adjacent to litR (TT_P0055), which encodes a CRP/FNR family transcriptional regulator, was unable to produce carotenoids, irrespective of light conditions. Overall, genetic and biochemical evidence indicates that LitR is bound by cobalamin and associates with the intergenic promoter region between litR and crtB (phytoene synthase gene), repressing the bidirectional transcription of litR and crtB. It is probable that derepression of LitR caused by some photodependent mechanism induces the expression of TT_P0055 protein, which serves as a transcriptional activator for the crtB operon and hence causes the expression of carotenoid biosynthesis and the DNA repair system under light condition.
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Pérez-Marín MC, Padmanabhan S, Polanco MC, Murillo FJ, Elías-Arnanz M. Vitamin B12 partners the CarH repressor to downregulate a photoinducible promoter in Myxococcus xanthus. Mol Microbiol 2008; 67:804-19. [PMID: 18315685 DOI: 10.1111/j.1365-2958.2007.06086.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A light-inducible promoter, P(B), drives expression of the carB operon in Myxococcus xanthus. Repressed by CarA in the dark, P(B) is activated when CarS, produced in the light, sequesters CarA to prevent operator-CarA binding. The MerR-type, N-terminal domain of CarA, which mediates interactions with both operator and CarS, is linked to a C-terminal oligomerization module with a predicted cobalamin-binding motif. Here, we show that although CarA does bind vitamin B12, mutating the motif involved has no effect on its ability to repress P(B). Intriguingly, P(B) could be repressed in the dark even with no CarA, so long as B12 and an intact CarA operator were present. We have discovered that this effect of B12 depends on the gene immediately downstream of carA. Its product, CarH, also consists of a MerR-type, N-terminal domain that specifically recognizes the CarA operator and CarS, linked to a predicted B12-binding C-terminal oligomerization module. The B12-mediated repression of P(B) in the dark is relieved by deleting carH, by mutating the DNA- or B12-binding residues of CarH, or by illumination. Our findings unveil parallel regulatory circuits that control a light-inducible promoter using a transcriptional factor repertoire that includes a paralogous gene pair and vitamin B12.
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Affiliation(s)
- Mari Cruz Pérez-Marín
- Departamento de Genética y Microbiología, Area de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia 30100, Spain
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van der Horst MA, Key J, Hellingwerf KJ. Photosensing in chemotrophic, non-phototrophic bacteria: let there be light sensing too. Trends Microbiol 2007; 15:554-62. [PMID: 18024131 DOI: 10.1016/j.tim.2007.09.009] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 09/18/2007] [Accepted: 09/19/2007] [Indexed: 10/22/2022]
Abstract
Putative light-sensing proteins are ubiquitously encoded in the genomes of chemotrophic, non-photosynthetic bacteria. Surprisingly, these are not limited to UV-receptors: the metagenome of the chemotrophic prokaryotes encodes representatives of all known major families of photoreceptors. Insight into the mechanism of light-mediated signaling is relatively advanced, but most light-induced physiological and behavioral responses in chemotrophic bacteria are not well understood. In the current era of 'omics' studies, this knowledge gap could be closed rapidly. Here we review the state of the art in this field. Because light signals can be manipulated accurately, these photoreceptors might help provide a systems-level understanding of the cytology of bacteria.
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Affiliation(s)
- Michael A van der Horst
- Laboratory for Microbiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands
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