Enhancement of a σB-dependent stress response in Bacillus subtilis by light via YtvA photoreceptor

Suzuki, Noriko; Takaya, Naoki; Hoshino, Takayuki; Nakamura, Akira

doi:10.2323/jgam.53.81

Cited by 32 publications

(41 citation statements)

References 26 publications

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“…Previous studies have shown that YtvA is a photoreceptor that acts in the environmental signaling pathway of the GSR, on (or upstream of) the main structural hub in this pathway: the stressosome (3,15,27,36). The stressosome can contain one or more proteins of the RsbR family-RsbRA, RsbRB, RsbRC, and RsbRD-which appear to be redundant (1,23).…”

Section: Resultsmentioning

confidence: 99%

“…3A). Previously, we and others had been unable to show a lightdependent activation of the GSR at wild-type expression levels of ytvA using the lacZ reporter, except when light stress was combined with an additional environmental stress, such as NaCl shock (3,36). To exclude the possibility that the observed activation was caused by a leaky promoter in the pYtvA plasmid, the triple null mutant strains, with only RsbRA (MA7) or only RsbRB (MA8) and without the pYtvA plasmid, were grown in the dark and exposed to continuous illumination from time point zero onward.…”

Section: Fig 2 Effects Of Double Null Mutations Of Rsbr Genes On the mentioning

confidence: 93%

“…YtvA was demonstrated to sense blue light with its N-terminal LOV (light, oxygen, voltage) domain in vitro (26). The loss or overproduction of YtvA abolishes or enhances, respectively, the environmental B response induced by moderate intensities of blue light (3,4,36). However, the light enhancement of the GSR by YtvA only becomes apparent when YtvA is overproduced or when light is combined with an additional environmental stress, such as NaCl shock (3,36).…”

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confidence: 99%

“…The loss or overproduction of YtvA abolishes or enhances, respectively, the environmental B response induced by moderate intensities of blue light (3,4,36). However, the light enhancement of the GSR by YtvA only becomes apparent when YtvA is overproduced or when light is combined with an additional environmental stress, such as NaCl shock (3,36). YtvA has been shown to act upstream of RsbU and RsbT (15), suggesting that it interacts with the stressosome.…”

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Differentiation of Function among the RsbR Paralogs in the General Stress Response of Bacillus subtilis with Regard to Light Perception

et al. 2012

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Section: Resultsmentioning

confidence: 99%

Section: Fig 2 Effects Of Double Null Mutations Of Rsbr Genes On the mentioning

confidence: 93%

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confidence: 99%

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confidence: 99%

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Differentiation of Function among the RsbR Paralogs in the General Stress Response of Bacillus subtilis with Regard to Light Perception

et al. 2012

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“…Little is known about the mechanism of signal transmission in and by YtvA, except that in the C62A mutant, photochemistry in vitro (12) and light activation of B in vivo (12,15) are abolished. More detailed information is available for LOV domains of phototropins.…”

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In Vivo Mutational Analysis of YtvA from Bacillus subtilis

Ávila-Pérez¹,

Vreede

Tang

et al. 2009

Journal of Biological Chemistry

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LOV2 domains (1), members of the superfamily of PAS domains (2, 3), are abundant in all domains of life and were first identified in plant phototropins (4). These photoreceptors regulate stomatal opening, phototropism, etc. and contain two N-terminal LOV domains that confer light regulation on the C-terminal Ser/Thr kinase domain (4). They also occur in bacteria, in which YtvA from Bacillus subtilis has been best characterized (for a review, see e.g. Ref. 5). Its N-terminal LOV domain binds FMN and shows the typical LOV photochemistry (6, 7): covalent adduct formation between a cysteine and the FMN chromophore. A linker helix, denoted J␣ (7), connects the LOV domain to a STAS domain. The latter domain is present in many regulators of the general stress response of B. subtilis (8,9). Stress via the addition of salt or ethanol (for a review, see Ref.10) and blue light (11, 12) activates the general stress response via the environmental pathway, which integrates various signals via a large multiprotein complex, called the stressosome (13,14). YtvA, which mediates light activation of B (11, 12, 15), co-purifies with other STAS domain proteins in the stressosomes (16). When cells are stressed, STAS domains of several stressosome proteins (e.g. RsbS and RsbR) are phosphorylated by another intrinsic stressosome component, the serine/threonine kinase RsbT (9,14,17,18). Next, RsbT is released from the complex to trigger RsbU, a protein phosphatase, thus (indirectly) activating B (19). Phosphorylation of YtvA, however, has never been detected. Rather, it has been demonstrated in vitro that YtvA shows light-dependent GTP binding, presumably at its NTP-binding site in the STAS domain (20).Little is known about the mechanism of signal transmission in and by YtvA, except that in the C62A mutant, photochemistry in vitro (12) and light activation of B in vivo (12, 15) are abolished. More detailed information is available for LOV domains of phototropins. A conserved glutamine, which is in hydrogen-bonding contact with the isoalloxazine ring of FMN, rotates its side chain by 180 o upon covalent adduct formation (21). Replacement of this residue by leucine in the LOV2 domain of Phy3 from Adiantum results in a considerable reduction of the light-induced structural change (22). The corresponding mutation in phototropin 1 from Arabidopsis impairs autophosphorylation activity (23). The signal generated in the LOV2 domain is transmitted to the downstream kinase domain of phototropin 1 of Avena sativa through disruption of the interaction between its central ␤-sheet and the C-terminal linker region, the J␣-helix (24).Here, we study the mechanism of activation of YtvA in vivo, i.e. light-induced activation of the B response, with site-directed mutagenesis. We focus on three regions of the protein, the flavinbinding pocket, the ␤-sheet of the LOV domain, and the GTPbinding site, and on potential phosphorylation sites of the STAS domain. We demonstrate that light-activated GTP binding is crucial for functional YtvA. A computational approac...

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Photoreception and Signal Transduction

Brandt

Frankenberg‐Dinkel

2009

Bacterial Signaling

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Enhancement of a σB-dependent stress response in Bacillus subtilis by light via YtvA photoreceptor

Cited by 32 publications

References 26 publications

Differentiation of Function among the RsbR Paralogs in the General Stress Response of Bacillus subtilis with Regard to Light Perception

Differentiation of Function among the RsbR Paralogs in the General Stress Response of Bacillus subtilis with Regard to Light Perception

In Vivo Mutational Analysis of YtvA from Bacillus subtilis

Photoreception and Signal Transduction

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