The roles of the chaperone-like protein CpeZ and the phycoerythrobilin lyase CpeY in phycoerythrin biogenesis

Kronfel, Christina M.; Biswas, Anup; Frick, Jacob P; Gutu, Andrian; Blensdorf, Tyler; Karty, Jonathan A.; Kehoe, David M.; Schluchter, Wendy M.

doi:10.1016/j.bbabio.2019.06.001

Cited by 10 publications

(14 citation statements)

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“…The lyase CpeS is able to attach PEB to CpeB ( Fig. 4 A ) as indicated by an absorbance peak at 559 nm, and its activity on CpeB increases in efficiency when coexpressed with CpeZ, a homolog of the characterized chaperone-like protein from F. diplosiphon ( 34 ) (see Fig. 4 B ).…”

Section: Resultsmentioning

confidence: 99%

“…PCC 7002, showing that lack of bilins at the central C82 equivalent position affects the stability and turnover rates of PBPs and reduces their folding and solubility in E. coli ( 10 , 17 , 21 , 46 , 51 , 52 ). Functionality and efficiency of some lyases are also known to depend upon substrate association with important chaperone-like proteins ( 14 , 30 , 34 , 53 ). Here, the chaperone-like protein CpeZ from RS9916, which is orthologous to the characterized CpeZ from F. diplosiphon , was shown to enhance the chromophorylation of CpeB and MpeB by MpeV and CpeS, presumably by stabilizing the β-subunits, preventing their aggregation, so that lyases could act ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…These lyases contain five to six HEAT-repeat motifs (thought to facilitate protein-protein interactions) coupled with Armadillo repeats (25)(26)(27)(28) (Figure S1) (4,22,29). This CpcE/F group also includes enzymes that have both bilin isomerase and ligase activity (lyase-isomerases), proteins with chaperone-like functions, and proteins with the capability to remove bilins (13,14,(30)(31)(32)(33)(34). To date, the crystal structure of only one CpcE/F type lyase has been solved and was found to adopt an alpha helical solenoid shape (29).…”

Section: Introductionmentioning

confidence: 99%

“…In F. diplosiphon, CpeS is the PEB lyase for C82 on CpeB and CpeF is the PEB lyase for the doubly ligated PEB at C50,61, and both of these enzymes require the chaperone-like protein CpeZ to keep the CpeB substrate soluble (34,46). In these recent studies, Kronfel et al also characterized the chromophorylation pattern for the doubly-linked PEB at C50, 61 in F. diplosiphon CpeB by CpeF and demonstrated that linkage along the A ring likely occurs first and is important for subsequent attachment to the D ring (46).…”

Section: Introductionmentioning

confidence: 99%

“…To date, no lyases for β-PEI or β-PEII have been characterized in RS9916, but some studies on the biosynthesis of CpeB from the freshwater cyanobacterium Fremyella diplosiphon have been completed ( 46 ). In F. diplosiphon , CpeS is the PEB lyase for C82 on CpeB and CpeF is the PEB lyase for the doubly ligated PEB at C50,61, and both of these enzymes require the chaperone-like protein CpeZ to keep the CpeB substrate soluble ( 34 , 46 ). In these recent studies, Kronfel et al.…”

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MpeV is a lyase isomerase that ligates a doubly linked phycourobilin on the β-subunit of phycoerythrin I and II in marine Synechococcus

Carrigee

Frick

Karty

et al. 2021

Journal of Biological Chemistry

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Synechococcus cyanobacteria are widespread in the marine environment, as the extensive pigment diversity within their light-harvesting phycobilisomes enables them to utilize various wavelengths of light for photosynthesis. The phycobilisomes of Synechococcus sp. RS9916 contain two forms of the protein phycoerythrin (PEI and PEII), each binding two chromophores, green-light absorbing phycoerythrobilin and blue-light absorbing phycourobilin. These chromophores are ligated to specific cysteines via bilin lyases, and some of these enzymes, called lyase-isomerases, attach phycoerythrobilin and simultaneously isomerize it to phycourobilin. MpeV is a putative lyase-isomerase whose role in PEI and PEII biosynthesis is not clear. We examined MpeV in RS9916 using recombinant protein expression, absorbance spectroscopy and tandem mass spectrometry. Our results show that MpeV is the lyase-isomerase that covalently attaches a doubly-linked phycourobilin to two cysteine residues (C50, C61) on the β-subunit of both PEI (CpeB) and PEII (MpeB). MpeV activity requires that CpeB or MpeB is first chromophorylated by the lyase CpeS (which adds phycoerythrobilin to C82). Its activity is further enhanced by CpeZ (a homolog of a chaperone-like protein first characterized in Fremyella diplosiphon). MpeV showed no detectable activity on the α-subunits of PEI or PEII. The mechanism by which MpeV links the A and D rings of phycourobilin to C50 and C61 of CpeB was also explored using site-directed mutants, revealing that linkage at the A ring to C50 is a critical step in chromophore attachment, isomerization and stability. These data provide novel insights into β-PE biosynthesis and advance our understanding of the mechanisms guiding lyase-isomerases.

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Section: Resultsmentioning

confidence: 99%