Structural highlights
Publication Abstract from PubMedThe distinct sequence feature and spectral blue-shift (~10 nm) of phycocyanin, isolated from Nostoc sp. R76DM (N-PC), were investigated by phylogenetic and crystallographic analyses. Twelve conserved substitutions in N-PC sequence were found distributed unequally among alpha- and beta-subunit (3 in alpha- and 9 in beta-subunit). The phylogenetic analysis suggested that molecular evolution of alpha- and beta-subunit of Nostoc-phycocyanin is faster than evolution of Nostoc-species. The divergence events seem to have occurred more frequently in beta-subunit, compared to alpha-subunit (relative divergence, 7.38 for alpha-subunit and 9.66 for beta-subunit). Crystal structure of N-PC was solved at 2.35 A resolution to reasonable R-factors (Rwork/RFree = 0.199/0.248). Substitutions congregate near interface of two alphabeta-monomer in N-PC trimer and are of compensatory nature. Six of the substitutions in beta-subunit may be involved in maintaining topology of beta-subunit, one in inter-monomer interaction and one in interaction with linker-protein. The beta153Cys-attached chromophore adopts high-energy conformational state resulting due to reduced coplanarity of B- and C-pyrrole rings. Distortion in chromophore conformation can result in blue-shift in N-PC spectral properties. N-PC showed significant in-vitro and in-vivo antioxidant activity comparable with other phycocyanin. Since Nostoc-species constitute a distinct phylogenetic clade, the present structure would provide a better template to build a model for phycocyanins of these species. Phylogenetic and crystallographic analysis of Nostoc phycocyanin having blue-shifted spectral properties.,Sonani RR, Rastogi RP, Patel SN, Chaubey MG, Singh NK, Gupta GD, Kumar V, Madamwar D Sci Rep. 2019 Jul 8;9(1):9863. doi: 10.1038/s41598-019-46288-4. PMID:31285455[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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