Two forms of the Photosystem II D1 protein alter energy dissipation and state transitions in the cyanobacterium Synechococcus sp. PCC 7942

Campbell, Douglas A.; Bruce, Doug; Carpenter, Christene; Gustafsson, Petter; Öquist, Gunnar

doi:10.1007/bf00016176

Cited by 45 publications

(41 citation statements)

References 57 publications

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“…Normally growing cells express the psbA1 gene and D1.1 is produced, but cells exposed to "excitation stress" predominantly express psbAII and psbAIII, leading to production of D1.2. Cells with D1.2 appear to be more resistant to excess excitation pressure than those possessing D1.1, and this in part derives from the higher intrinsic resistance of PSII containing D1.2 to photoinhibition (8,9) that may be due to an alteration in the redox behavior of the reaction center (58). When the phage-encoded D1 protein is compared with D1.1 and D1.2, it shares all the amino acid features in the transmembrane helices of D1.2, suggesting that it is a high-light form.…”

Section: Resultsmentioning

confidence: 99%

The Genome of S-PM2, a “Photosynthetic” T4-Type Bacteriophage That Infects Marine Synechococcus Strains

et al. 2005

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Bacteriophage S-PM2 infects several strains of the abundant and ecologically important marine cyanobacterium Synechococcus. A large lytic phage with an isometric icosahedral head, S-PM2 has a contractile tail and by this criterion is classified as a myovirus ( Strains of unicellular cyanobacteria of the genera Synechococcus and Prochlorococcus are abundant in the world's oceans and constitute the prokaryotic component of the picophytoplankton. Together, these photosynthetic bacteria contribute a significant proportion of primary production in oligotrophic regions of the oceans (21,35,37,68). Viral infection of marine unicellular cyanobacteria was first reported in 1990 (53, 63), and cyanovirus isolates were first characterized in the laboratory in 1993 (62,69,74). The majority of these phages belong to the myoviruses. Myoviruses are physically robust and remarkably versatile; this virion design can apparently be easily adapted to a variety of different ecological niches (64). S-PM2 is a lytic cyanomyovirus with an icosahedral head and long contractile tail that infects marine Synechococcus strains. The genome has been shown to have a size of ϳ194 kb (27). Bacteriophage T4 that infects Escherichia coli is the archetype myovirus, and S-PM2 was shown to have a genetic module that encodes distant homologues of most of the major virion proteins of T4 (27). T4 has been extensively studied and is extremely well understood; it serves as a superb, if somewhat complex, model for S-PM2.A previous phylogenetic analysis of the sequences of the major head and tail genes of a wide range of T4-type bacteriophages indicated at least three distinct phylogenetic subgroups of these phages (64). There is a large cluster of phages, termed the T-evens, members of which are all closely related to T4, the archetype of the Myoviridae. The second subgroup is surprisingly phylogenetically divergent from the T-evens, but morphologically similar; these are called the pseudoT-evens (47), and they includes phages such as RB49 and RB42 that infect E. coli. The third cluster includes Aeromonas phages and vibriophages such as nt-1, KVP20, KVP40, 65, and Aeh1. Such phages have heads that are more elongated than those of both T-evens and the pseudoT-evens and thus are called the schizoT-evens (64). Phylogenetic analysis based on the major capsid protein gp23 has shown that S-PM2 and the related cyanomyovirus S-PWM3 are quite distinct from the other characterized T4-like phages and form a new discrete group, the exoT-evens (27). These marine T4-type phages have apparently diverged significantly from the T4 archetype. Beyond the fact that they have a contractile tail, these phages have little morphological resemblance to the other T4-type phages. Among the many differences between the exoT-evens and the other T-type phages are those that relate to the photosynthetic physiology of their hosts. It is clear that S-PM2 (41) and several other marine cyanomyoviruses (36, 43) encode homologues of the D1 and D2 proteins of the host photosystem II that presum...

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Section: Resultsmentioning

confidence: 99%

The Genome of S-PM2, a “Photosynthetic” T4-Type Bacteriophage That Infects Marine Synechococcus Strains

et al. 2005

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“…Following exposure of cells to HL, the D1:1 isoform encoded by psbA1 declined, while the D1:2 isoform encoded by psbA2-4 increased 7-to 60-fold. In freshwater Synechococcus PCC 7942, an increase in D1:2 transcription and D1:2 polypeptide composition of the PSII reaction center is associated with greater resistance to photoinhibition through improved dissipation of excess absorbed light energy (Schaefer & Golden 1989a, Krupa et al 1991, Clarke et al 1993, Campbell et al 1996. Unlike the situation in fresh water Synechococcus If most D1 proteins in PSII were non-functional, resulting in an F v /F m approaching zero, we would expect that most cells would be unable to perform photosynthesis and rapidly lose viability.…”

Section: Discussionmentioning

confidence: 99%

Responses of psbA, hli and ptox genes to changes in irradiance in marine Synechococcus and Prochlorococcus

Gm¹,

Shrager²,

Dijken³

et al. 2011

Aquat. Microb. Ecol.

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Expression of 3 gene families involved with photoacclimation -psbA (encoding the photosystem II reaction center protein D1), hli (encoding the high-light inducible proteins), and ptox (encoding the plastid terminal oxidase) -was compared in the marine cyanobacteria Synechococcus WH8102 and Prochlorococcus MED4 acclimated to either low or high light. These 2 strains, adapted for growth in oligotrophic marine environments, have distinct light-harvesting systems and respond differently to changes in irradiance. In response to growth at higher irradiance, Synechococcus WH8102 increased expression of the psbA multigene family ( psbA1-4) 5-fold. Within this gene family, the expression of psbA2 increased 60-fold. Expression of 4 hli genes increased 2-to 5-fold, whereas expression of the ptox gene decreased 3-fold. In comparison, expression of the psbA gene increased 2-fold in Prochlorococcus MED4 cultures grown at higher irradiances. Expression of the Prochlorococcus MED4 hli6-9 and hli16-19 operons increased 11-to 14-fold, while ptox expression increased 3-fold. Using psbA induction as a standard for acclimation to changes in irradiance, we observed that the induction ratio of ptox:psbA1 and hli:psbA1 was 144 and 70 times greater, respectively, in Prochlorococcus MED4 compared with Synechococcus WH8102. These observations suggest that induction of ptox and hli may play a key role in the phototolerance of Prochlorococcus MED4. Conversely, the induction of psbA, and the synthesis of the PSII reaction center protein D1, may be critical for the acclimation of Synechococcus WH8102 to high irradiances.KEY WORDS: Synechococcus WH8102 · Prochlorococcus MED4 · Photoacclimation · Photoinhibition · Gene expression · psbA · hli · ptox · Fluorescence characterization · Carbon fixation Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 65: [1][2][3][4][5][6][7][8][9][10][11][12][13][14] 2011 mophores PCB and phycoerythrobilin (PEB), and PE binds the chromophores PEB and phycourobilin (PUB) to harvest light. In contrast, Prochlorococcus relies on integral thylakoid membrane proteins (Pcbs) that bind divinyl chlorophyll a and b to harvest light energy. The Pcbs of Prochlorococcus MED4 form a ring around PSII (Bibby et al. 2003), their Fig. 1.High irradiance in the uppermost layer of the ocean can lead to photoinhibition and loss of function of the photosynthetic apparatus. During photosynthesis, an electron from an excited chlorophyll molecule is transferred to the primary electron acceptor pheophytin and then on to the quinone molecules (Q A and Q B ) of the plastoquinone (PQ) pool. From the PQ pool, electrons are transferred to cytochrome b 6f , plastocyanin, and finally, through photosystem I (PSI), to reduce NADP + in the classical z scheme (Fig. 1). Photoinhibition results when the PQ pool becomes over-reduced (Vass et al. 1992) or during charge recombination between PSII acceptor and donor sides (Keren et al. 1997 The phycobilisome (PBS) light-harvesting system is compo...

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“…This raises the question of why Synechococcus maintains D1:1. We have some biophysical evidence that the D1:1 protein may prove superior under low and fluctuating light (53), which may account for the maintenance of two D1 forms over evolutionary time. Other workers have speculated that strains such as Synechococcus with phycocyanin-rich phycobilisomes may be more sensitive to UV-B than are strains with phycobilisomes containing phycoerythrin (19).…”

Section: Uv-b Strongly Regulatesmentioning

confidence: 97%

“…7), showing no significant inhibition of PSII function and only a modest drop in electron transport to 85% of control after 120 min of UV-B exposure. Under control conditions, the R2K1 and R2S2C3 strains have similar levels of total D1 protein (27,53).…”

Section: Uv-b Strongly Regulatesmentioning

confidence: 99%

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The cyanobacterium Synechococcus resists UV-B by exchanging photosystem II reaction-center D1 proteins

Campbell

Eriksson

Öquist

et al. 1998

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

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172

117

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Current ambient UV-B levels can significantly depress productivity in aquatic habitats, largely because UV-B inhibits several steps of photosynthesis, including the photooxidation of water catalyzed by photosystem II. We show that upon UV-B exposure the cyanobacterium Synechococcus sp. PCC 7942 rapidly changes the expression of a family of three psbA genes encoding photosystem II D1 proteins. In wild-type cells the psbAI gene is expressed constitutively, but strong accumulations of psbAII and psbAIII transcripts are In oxygenic photobionts, photosystem II (PSII) is an integral membrane complex that catalyzes the photooxidation of water, with concomitant release of oxygen. Electrons extracted from water are passed to plastoquinone and enter the photosynthetic electron transport chain. The core of the PSII complex is composed of a dimer of two related proteins, D1 and D2, that bind the pigments and cofactors involved in this electron transfer from water to plastoquinone. During active photosynthesis the D1 protein, and to a lesser extent D2, turn over rapidly and are replaced by newly synthesized polypeptides in a PSII repair cycle. Under environmental stress, the repair cycle can be impaired, such that degradation and loss of D1 protein exceeds the rate of replacement (1). This net loss of functional D1 leads to a drop in PSII function and can contribute to photoinhibition, a light-dependent drop in the quantum yield of photosynthesis. Photoinhibition usually occurs when excitation capture exceeds the rate of electron removal from the PSII complex, as can occur when the light intensity exceeds the acclimated irradiance or when the temperature drops below the acclimated level.

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Two forms of the Photosystem II D1 protein alter energy dissipation and state transitions in the cyanobacterium Synechococcus sp. PCC 7942

Cited by 45 publications

References 57 publications

The Genome of S-PM2, a “Photosynthetic” T4-Type Bacteriophage That Infects Marine Synechococcus Strains

The Genome of S-PM2, a “Photosynthetic” T4-Type Bacteriophage That Infects Marine Synechococcus Strains

Responses of psbA, hli and ptox genes to changes in irradiance in marine Synechococcus and Prochlorococcus

The cyanobacterium Synechococcus resists UV-B by exchanging photosystem II reaction-center D1 proteins

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