气候变化领域集成服务门户(CCPortal): The LarB carboxylase/hydrolase forms a transient cysteinyl-pyridine intermediate during nickel-pincer nucleotide cofactor biosynthesis

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DOI	10.1073/pnas.2106202118
	The LarB carboxylase/hydrolase forms a transient cysteinyl-pyridine intermediate during nickel-pincer nucleotide cofactor biosynthesis
	Rankin J.A.; Chatterjee S.; Tariq Z.; Lagishetty S.; Desguin B.; Hu J.; Hausinger R.P.
发表日期	2021
ISSN	0027-8424
卷号	118 期号:39
英文摘要	Enzymes possessing the nickel-pincer nucleotide (NPN) cofactor catalyze C2 racemization or epimerization reactions of α-hydroxyacid substrates. LarB initiates synthesis of the NPN cofactor from nicotinic acid adenine dinucleotide (NaAD) by performing dual reactions: pyridinium ring C5 carboxylation and phosphoanhydride hydrolysis. Here, we show that LarB uses carbon dioxide, not bicarbonate, as the substrate for carboxylation and activates water for hydrolytic attack on the AMP-associated phosphate of C5-carboxylated-NaAD. Structural investigations show that LarB has an N-terminal domain of unique fold and a C-terminal domain homologous to aminoimidazole ribonucleotide carboxylase/mutase (PurE). Like PurE, LarB is octameric with four active sites located at subunit interfaces. The complex of LarB with NAD+, an analog of NaAD, reveals the formation of a covalent adduct between the active site Cys221 and C4 of NAD+, resulting in a boat-shaped dearomatized pyridine ring. The formation of such an intermediate with NaAD would enhance the reactivity of C5 to facilitate carboxylation. Glu180 is well positioned to abstract the C5 proton, restoring aromaticity as Cys221 is expelled. The structure of as-isolated LarB and its complexes with NAD+ and the product AMP identify additional residues potentially important for substrate binding and catalysis. In combination with these findings, the results from structure-guided mutagenesis studies lead us to propose enzymatic mechanisms for both the carboxylation and hydrolysis reactions of LarB that are distinct from that of PurE. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Carboxylation; Covalent adduct; Hydrolysis; Nickel-pincer cofactor
语种	英语
scopus关键词	carboxylyase; cysteine; hydrolase; isomerase; nickel; nucleotide; pyridine derivative; biosynthesis; catalysis; chemistry; enzyme specificity; enzymology; hydrolysis; Lactobacillus plantarum; metabolism; molecular model; protein conformation; X ray crystallography; Carboxy-Lyases; Catalysis; Crystallography, X-Ray; Cysteine; Hydrolases; Hydrolysis; Lactobacillus plantarum; Models, Molecular; Nickel; Nucleotides; Protein Conformation; Pyridines; Racemases and Epimerases; Substrate Specificity
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/238369
作者单位	Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, United States; Institute of Biomolecular Sciences and Technology, Université Catholique de Louvain, Louvain-La-Neuve, B-1348, Belgium; Department of Chemistry, Michigan State University, East Lansing, MI 48824, United States
推荐引用方式 GB/T 7714	Rankin J.A.,Chatterjee S.,Tariq Z.,et al. The LarB carboxylase/hydrolase forms a transient cysteinyl-pyridine intermediate during nickel-pincer nucleotide cofactor biosynthesis[J],2021,118(39).
APA	Rankin J.A..,Chatterjee S..,Tariq Z..,Lagishetty S..,Desguin B..,...&Hausinger R.P..(2021).The LarB carboxylase/hydrolase forms a transient cysteinyl-pyridine intermediate during nickel-pincer nucleotide cofactor biosynthesis.Proceedings of the National Academy of Sciences of the United States of America,118(39).
MLA	Rankin J.A.,et al."The LarB carboxylase/hydrolase forms a transient cysteinyl-pyridine intermediate during nickel-pincer nucleotide cofactor biosynthesis".Proceedings of the National Academy of Sciences of the United States of America 118.39(2021).