Redox-dependent Ligand Switching in a Sensory Heme-binding GAF Domain of the Cyanobacterium Nostoc sp. PCC7120

Tang, Kun; Knipp, Markus; Liu, Bingbing; Cox, Nicholas; Stabel, Robert; He, Qi; Zhou, Ming; Scheer, Hugo; Zhao, Kai‐Hong; Gärtner, Wolfgang

doi:10.1074/jbc.m115.654087

Cited by 11 publications

(7 citation statements)

References 70 publications

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“…Mx GacB harbors the GAF domain, which was first identified by Aravind and colleagues and named for its presence in cGMP‐specific phosphodiesterases, Anabaena adenylate cyclases and Escherichia coli FhlA (Aravind and Ponting, ). Since then, GAF domains have been shown to respond to a diverse set of small molecule signals, including cyclic nucleotides, amino acids and metabolites, as well as redox and light (Little and Dixon, ; Sardiwal et al , ; Heikaus et al , ; Villapakkam et al , ; Enomoto et al , ; Tang et al , ). Our initial in vitro experiments with Mx GacB included measuring enzyme activity in the presence of ATP, GTP and related analogs.…”

Section: Resultsmentioning

confidence: 99%

Second messengers and divergent HD‐GYP phosphodiesterases regulate 3′,3′‐cGAMP signaling

Wright

Jiang

Park

et al. 2019

Molecular Microbiology

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3′,3′-cyclic GMP-AMP (cGAMP) is the third cyclic dinucleotide (CDN) to be discovered in bacteria. No activators of cGAMP signaling have yet been identified, and the signaling pathways for cGAMP have been inferred to display a narrow distribution based upon the characterized synthases, DncV and Hypr GGDEFs. Here, we report that the ubiquitous second messenger cyclic AMP (cAMP) is an activator of the Hypr GGDEF enzyme GacB from Myxococcus xanthus. Furthermore, we show that GacB is inhibited directly by cyclic di-GMP, which provides evidence for crossregulation between different CDN pathways. Finally, we reveal that the HD-GYP enzyme PmxA is a cGAMPspecific phosphodiesterase (GAP) that promotes resistance to osmotic stress in M. xanthus. A signature amino acid change in PmxA was found to reprogram substrate specificity and was applied to predict the presence of non-canonical HD-GYP phosphodiesterases in many bacterial species, including phyla previously not known to utilize cGAMP signaling.

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Section: Resultsmentioning

confidence: 99%

Second messengers and divergent HD‐GYP phosphodiesterases regulate 3′,3′‐cGAMP signaling

Wright

Jiang

Park

et al. 2019

Molecular Microbiology

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“…Our findings with the three cyt c variants used to validate this approach are fully consistent with other characterization methods from studies by others or performed in this work. Further, new kinetic data and redox-dependent p K a values for K79H and T78C/K79G have uncovered properties of conformers involved in redox-linked ligand switching, − a mechanism common to biological sensors and redox metalloenzymes. We anticipate that this ITC method will find exciting applications in studies of PCET reactions of other metalloproteins, including those where thermodynamic information about ET and PT sites might be difficult to obtain by other means.…”

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confidence: 99%

Mechanistic Studies of Proton-Coupled Electron Transfer in a Calorimetry Cell

Zhong

Pletneva

2019

J. Am. Chem. Soc.

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Mechanistic studies of proton-coupled electron-transfer (PCET) reactions in proteins are complicated by the challenge of following proton transfer (PT) in these large molecules. Herein we describe the use of isothermal titration calorimetry (ITC) to establish proton involvement in protein redox reactions and the identity of PT sites. We validate this approach with three variants of a heme protein cytochrome c (cyt c) and show that the method yields a wealth of thermodynamic information that is important for characterizing PCET reactions, including reduction potentials, redox-dependent pK a values, and reaction enthalpies for both electron-transfer (ET) and PT steps. We anticipate that this facile and label-free ITC approach will find widespread applications in studies of other redox proteins and enhance our knowledge of PCET reaction mechanisms.

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“…Considering the harsh conditions of N. flagelliforme habitats, we hypothesize that these proteins may respond to a variety of other environmental signals (e.g. UV and osmotic pressure) by binding other small molecules (such as cNMP and heme) (Bruder et al, 2005;Tang et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Expansion of bilin‐based red light sensors in the subaerial desert cyanobacterium Nostoc flagelliforme

Dai

Wang

et al. 2022

Environmental Microbiology

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Light is the crucial environmental signal for desiccation-tolerant cyanobacteria to activate photosynthesis and prepare for desiccation at dawn. However, the photobiological characteristics of desert cyanobacteria adaptation to one of the harshest habitats on Earth remain unresolved. In this study, we surveyed the genome of a subaerial desert cyanobacterium Nostoc flagelliforme and identified two phytochromes and seven cyanobacteriochromes (CBCRs) with one or more bilin-binding GAF (cGMP phosphodiesterase/adenylyl cyclase/FhlA) domains. Biochemical and spectroscopic analyses of 69 purified GAF-containing proteins from recombinant phycocyanobilin (PCB), biliverdin or phycoerythrobilin-producing Escherichia coli indicated that nine of these proteins bind chromophores. Further investigation revealed that 11 GAFs form covalent adducts responsive to near-UV and visible light: eight GAFs contained PCB chromophores, three GAFs contained biliverdin chromophores and one contained the PCB isomer, phycoviolobilin. Interestingly, COO91_03972 is the first-ever reported GAF-only CBCR capable of sensing five wavelengths of light. Bioinformatics and biochemical analyses revealed that residue P132 of COO91_03972 is essential for chromophore binding to dual-cysteine CBCRs. Furthermore, the complement of N. flagelliforme CBCRs is enriched in red light sensors. We hypothesize that these sensors are critical for the acclimatization of N. flagelliforme to weak light environments at dawn.

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Redox-dependent Ligand Switching in a Sensory Heme-binding GAF Domain of the Cyanobacterium Nostoc sp. PCC7120

Cited by 11 publications

References 70 publications

Second messengers and divergent HD‐GYP phosphodiesterases regulate 3′,3′‐cGAMP signaling

Second messengers and divergent HD‐GYP phosphodiesterases regulate 3′,3′‐cGAMP signaling

Mechanistic Studies of Proton-Coupled Electron Transfer in a Calorimetry Cell

Expansion of bilin‐based red light sensors in the subaerial desert cyanobacterium Nostoc flagelliforme

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