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Structural bases for aspartate recognition and polymerization efficiency of cyanobacterial cyanophycin synthetase

Cyanophycin is a natural biopolymer consisting of equimolar amounts of aspartate and arginine as the backbone and branched sidechain, respectively. It is produced by a single enzyme, cyanophycin synthetase (CphA1), and accumulates as a nitrogen reservoir during N(2) fixation by most cyanobacteria. A...

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Detalles Bibliográficos
Autores principales: Miyakawa, Takuya, Yang, Jian, Kawasaki, Masato, Adachi, Naruhiko, Fujii, Ayumu, Miyauchi, Yumiko, Muramatsu, Tomonari, Moriya, Toshio, Senda, Toshiya, Tanokura, Masaru
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9427784/
https://www.ncbi.nlm.nih.gov/pubmed/36042318
http://dx.doi.org/10.1038/s41467-022-32834-8
Descripción
Sumario:Cyanophycin is a natural biopolymer consisting of equimolar amounts of aspartate and arginine as the backbone and branched sidechain, respectively. It is produced by a single enzyme, cyanophycin synthetase (CphA1), and accumulates as a nitrogen reservoir during N(2) fixation by most cyanobacteria. A recent structural study showed that three constituent domains of CphA1 function as two distinct catalytic sites and an oligomerization interface in cyanophycin synthesis. However, it remains unclear how the ATP-dependent addition of aspartate to cyanophycin is initiated at the catalytic site of the glutathione synthetase-like domain. Here, we report the cryogenic electron microscopy structures of CphA1, including a complex with aspartate, cyanophycin primer peptide, and ATP analog. These structures reveal the aspartate binding mode and phosphate-binding loop movement to the active site required for the reaction. Furthermore, structural and mutational data show a potential role of protein dynamics in the catalytic efficiency of the arginine condensation reaction.