@article {carrigee_phycoerythrobilin_2022,
	title = {The phycoerythrobilin isomerization activity of MpeV in Synechococcus sp. WH8020 is prevented by the presence of a histidine at position 141 within its phycoerythrin-I β-subunit substrate},
	journal = {Frontiers in Microbiology},
	volume = {13},
	year = {2022},
	pages = {1011189},
	abstract = {Marine Synechococcus efficiently harvest available light for photosynthesis using complex antenna systems, called phycobilisomes, composed of an allophycocyanin core surrounded by rods, which in the open ocean are always constituted of phycocyanin and two phycoerythrin (PE) types: PEI and PEII. These cyanobacteria display a wide pigment diversity primarily resulting from differences in the ratio of the two chromophores bound to PEs, the green-light absorbing phycoerythrobilin and the blue-light absorbing phycourobilin. Prior to phycobiliprotein assembly, bilin lyases post-translationally catalyze the ligation of phycoerythrobilin to conserved cysteine residues on α- or β-subunits, whereas the closely related lyase-isomerases isomerize phycoerythrobilin to phycourobilin during the attachment reaction. MpeV was recently shown in Synechococcus sp. RS9916 to be a lyase-isomerase which doubly links phycourobilin to two cysteine residues (C50 and C61; hereafter C50, 61) on the β-subunit of both PEI and PEII. Here we show that Synechococcus sp. WH8020, which belongs to the same pigment type as RS9916, contains MpeV that demonstrates lyase-isomerase activity on the PEII β-subunit but only lyase activity on the PEI β-subunit. We also demonstrate that occurrence of a histidine at position 141 of the PEI β-subunit from WH8020, instead of a leucine in its counterpart from RS9916, prevents the isomerization activity by WH8020 MpeV, showing for the first time that both the substrate and the enzyme play a role in the isomerization reaction. We propose a structural-based mechanism for the role of H141 in blocking isomerization. More generally, the knowledge of the amino acid present at position 141 of the β-subunits may be used to predict which phycobilin is bound at C50, 61 of both PEI and PEII from marine Synechococcus strains.},
	keywords = {RCC2437, RCC307, RCC751},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2022.1011189},
	url = {https://www.frontiersin.org/articles/10.3389/fmicb.2022.1011189/full},
	author = {Carrigee, Lyndsay A. and Frick, Jacob P. and Liu, Xindi and Karty, Jonathan A. and Trinidad, Jonathan C. and Tom, Irin P. and Yang, Xiaojing and Dufour, Louison and Partensky, Fr{\'e}d{\'e}ric and Schluchter, Wendy M.}
}
@article {grebert_molecular_2021,
	title = {Molecular bases of an alternative dual-enzyme system for light color acclimation of marine \textit{Synechococcus cyanobacteria},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {118},
	number = {9},
	year = {2021},
	pages = {e2019715118},
	abstract = {<p>Marine Synechococcus cyanobacteria owe their ubiquity in part to the wide pigment diversity of their light-harvesting complexes. In open ocean waters, cells predominantly possess sophisticated antennae with rods composed of phycocyanin and two types of phycoerythrins (PEI and PEII). Some strains are specialized for harvesting either green or blue light, while others can dynamically modify their light absorption spectrum to match the dominant ambient color. This process, called type IV chromatic acclimation (CA4), has been linked to the presence of a small genomic island occurring in two configurations (CA4-A and CA4-B). While the CA4-A process has been partially characterized, the CA4-B process has remained an enigma. Here we characterize the function of two members of the phycobilin lyase E/F clan, MpeW and MpeQ, in Synechococcus sp. strain A15-62 and demonstrate their critical role in CA4-B. While MpeW, encoded in the CA4-B island and up-regulated in green light, attaches the green light-absorbing chromophore phycoerythrobilin to cysteine-83 of the PEII α-subunit in green light, MpeQ binds phycoerythrobilin and isomerizes it into the blue light-absorbing phycourobilin at the same site in blue light, reversing the relationship of MpeZ and MpeY in the CA4-A strain RS9916. Our data thus reveal key molecular differences between the two types of chromatic acclimaters, both highly abundant but occupying distinct complementary ecological niches in the ocean. They also support an evolutionary scenario whereby CA4-B island acquisition allowed former blue light specialists to become chromatic acclimaters, while former green light specialists would have acquired this capacity by gaining a CA4-A island.</p>
},
	keywords = {RCC2374, to add},
	issn = {0027-8424, 1091-6490},
	doi = {10.1073/pnas.2019715118},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.2019715118},
	author = {Gr{\'e}bert, Th{\'e}ophile and Nguyen, Adam A. and Pokhrel, Suman and Joseph, Kes Lynn and Ratin, Morgane and Dufour, Louison and Chen, Bo and Haney, Allissa M. and Karty, Jonathan A. and Trinidad, Jonathan C. and Garczarek, Laurence and Schluchter, Wendy M. and Kehoe, David M. and Partensky, Fr{\'e}d{\'e}ric}
}
@article {Carrigee2020,
	title = {CpeY is a phycoerythrobilin lyase for cysteine 82 of the phycoerythrin I <span class="nocase">α</span>-subunit in marine Synechococcus},
	journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},
	year = {2020},
	note = {Publisher: Elsevier B.V tex.mendeley-tags: RCC555},
	month = {apr},
	pages = {148215},
	keywords = {rcc555},
	issn = {00052728},
	doi = {10.1016/j.bbabio.2020.148215},
	url = {https://doi.org/10.1016/j.bbamem.2019.183135 https://linkinghub.elsevier.com/retrieve/pii/S0005272820300657},
	author = {Carrigee, Lyndsay A. and Mahmoud, Rania M. and Sanfilippo, Joseph E. and Frick, Jacob P. and Strnat, Johann A. and Karty, Jonathan A. and Chen, Bo and Kehoe, David M. and Schluchter, Wendy M.}
}
@article {Sanfilippo2019,
	title = {Interplay between differentially expressed enzymes contributes to light color acclimation in marine Synechococcus},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {116},
	number = {13},
	year = {2019},
	note = {tex.mendeley-tags: RCC1086,RCC2035,RCC2380,RCC2382,RCC2385,RCC2433,RCC2437,RCC2528,RCC2533,RCC2534,RCC2535,RCC2571,RCC2673,RCC28,RCC307,RCC328,RCC515,RCC555,RCC791},
	month = {mar},
	pages = {6457{\textendash}6462},
	abstract = {Marine Synechococcus , a globally important group of cyanobacteria, thrives in various light niches in part due to its varied photosynthetic light-harvesting pigments. Many Synechococcus strains use a process known as chromatic acclimation to optimize the ratio of two chromophores, green-light{\textendash}absorbing phycoerythrobilin (PEB) and blue-light{\textendash}absorbing phycourobilin (PUB), within their light-harvesting complexes. A full mechanistic understanding of how Synechococcus cells tune their PEB to PUB ratio during chromatic acclimation has not yet been obtained. Here, we show that interplay between two enzymes named MpeY and MpeZ controls differential PEB and PUB covalent attachment to the same cysteine residue. MpeY attaches PEB to the light-harvesting protein MpeA in green light, while MpeZ attaches PUB to MpeA in blue light. We demonstrate that the ratio of mpeY to mpeZ mRNA determines if PEB or PUB is attached. Additionally, strains encoding only MpeY or MpeZ do not acclimate. Examination of strains of Synechococcus isolated from across the globe indicates that the interplay between MpeY and MpeZ uncovered here is a critical feature of chromatic acclimation for marine Synechococcus worldwide.},
	keywords = {RCC1086, RCC2035, rcc2380, rcc2382, RCC2385, RCC2433, RCC2437, RCC2528, RCC2533, RCC2534, RCC2535, RCC2571, RCC2673, RCC28, RCC307, RCC328, RCC515, rcc555, rcc791},
	issn = {0027-8424},
	doi = {10.1073/pnas.1810491116},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1810491116},
	author = {Sanfilippo, Joseph E. and Nguyen, Adam A. and Garczarek, Laurence and Karty, Jonathan A. and Pokhrel, Suman and Strnat, Johann A. and Partensky, Fr{\'e}d{\'e}ric and Schluchter, Wendy M. and Kehoe, David M.}
}
@article {Mahmoud2017,
	title = {Adaptation to blue light in marine synechococcus requires MpeU, an enzyme with similarity to phycoerythrobilin lyase isomerases},
	journal = {Frontiers in Microbiology},
	volume = {8},
	number = {February},
	year = {2017},
	note = {tex.mendeley-tags: 2017,rcc555,sbr?hyto?app},
	month = {feb},
	pages = {243},
	abstract = {Marine Synechococcus cyanobacteria have successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant photosynthetic microorganism worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, produced impaired phycobilisomes and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world{\textquoteright}s oceans.},
	keywords = {2017, Blue light, light harvesting complex, Lyase isomerase, marine cyanobacteria, Marine Synechococcus, phycobilin, Phycobilisome, Phycoerythrin, Phycourobilin, rcc555, sbr?hyto?app},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2017.00243},
	url = {http://journal.frontiersin.org/article/10.3389/fmicb.2017.00243/full},
	author = {Mahmoud, Rania M. and Sanfilippo, Joseph E. and Nguyen, Adam A. and Strnat, Johann A. and Partensky, Fr{\'e}d{\'e}ric and Garczarek, Laurence and Abo El Kassem, Nabil and Kehoe, David M. and Schluchter, Wendy M.}
}
