25191-17-7Relevant articles and documents
Protein thiocarboxylate-dependent methionine biosynthesis in Wolinella succinogenes
Krishnamoorthy, Kalyanaraman,Begley, Tadhg P.
, p. 379 - 386 (2011)
Thiocarboxylated proteins are important intermediates in a variety of biochemical sulfide transfer reactions. Here we identify a protein thiocarboxylate-dependent methionine biosynthetic pathway in Wolinella succinogenes. In this pathway, the carboxy terminal alanine of a novel sulfur transfer protein, HcyS-Ala, is removed in a reaction catalyzed by a metalloprotease, HcyD. HcyF, an ATP-utilizing enzyme, catalyzes the adenylation of HcyS. HcyS acyl-adenylate then undergoes nucleophilic substitution by bisulfide produced by Sir to give the HcyS thiocarboxylate. This adds to O-acetylhomoserine to give HcyS-homocysteine in a PLP-dependent reaction catalyzed by MetY. HcyD-mediated hydrolysis liberates homocysteine. A final methylation completes the biosynthesis. The biosynthetic gene cluster also encodes the enzymes involved in the conversion of sulfate to sulfide suggesting that sulfate is the sulfur source for protein thiocarboxylate formation in this system.
Recreating the natural evolutionary trend in key microdomains provides an effective strategy for engineering of a thermomicrobial N-demethylase
Gu, Zhenghua,Guo, Zitao,Shao, Jun,Shen, Chen,Shi, Yi,Tang, Mengwei,Xin, Yu,Zhang, Liang
, (2022/03/09)
N-demethylases have been reported to remove the methyl groups on primary or secondary amines, which could further affect the properties and functions of biomacromolecules or chemical compounds; however, the substrate scope and the robustness of N-demethylases have not been systematically investigated. Here we report the recreation of natural evolution in key microdomains of the Thermomicrobium roseum sarcosine oxidase (TrSOX), an N-demethylase with marked stability (melting temperature over 100 C) and enantioselectivity, for enhanced substrate scope and catalytic efficiency on -C-N-bonds. We obtained the structure of TrSOX by crystallization and X-ray diffraction (XRD) for the initial framework. The natural evolution in the nonconserved residues of key microdomains—including the catalytic loop, coenzyme pocket, substrate pocket, and entrance site—was then identified using ancestral sequence reconstruction (ASR), and the substitutions that accrued during natural evolution were recreated by site-directed mutagenesis. The single and double substitution variants catalyzed the N-demethylation of N-methyl-L-amino acids up to 1800- and 6000-fold faster than the wild type, respectively. Additionally, these single substitution variants catalyzed the terminal N-demethylation of non-amino-acid compounds and the oxidation of the main chain -C-N- bond to a -C=N- bond in the nitrogen-containing heterocycle. Notably, these variants retained the enantioselectivity and stability of the initial framework. We conclude that the variants of TrSOX are of great potential use in N-methyl enantiomer resolution, main-chain Schiff base synthesis, and alkaloid modification or degradation.
Biosynthesis ofl-alanine fromcis-butenedioic anhydride catalyzed by a triple-enzyme cascadeviaa genetically modified strain
Cui, Ruizhi,Liu, Zhongmei,Yu, Puyi,Zhou, Li,Zhou, Zhemin
supporting information, p. 7290 - 7298 (2021/09/28)
In industry,l-alanine is biosynthesized using fermentation methods or catalyzed froml-aspartic acid by aspartate β-decarboxylase (ASD). In this study, a triple-enzyme system was developed to biosynthesizel-alanine fromcis-butenedioic anhydride, which was cost-efficient and could overcome the shortcomings of fermentation. Maleic acid formed bycis-butenedioic anhydride dissolving in water was transformed tol-alanineviafumaric acid andl-asparagic acid catalyzed by maleate isomerase (MaiA), aspartase (AspA) and ASD, respectively. The enzymatic properties of ASD from different origins were investigated and compared, as ASD was the key enzyme of the triple-enzyme cascade. Based on cofactor dependence and cooperation with the other two enzymes, a suitable ASD was chosen. Two of the three enzymes, MaiA and ASD, were recombinant enzymes cloned into a dual-promoter plasmid for overexpression; another enzyme, AspA, was the genomic enzyme of the host cell, in which AspA was enhanced by a T7promoter. Two fumarases in the host cell genome were deleted to improve the utilization of the intermediate fumaric acid. The conversion of whole-cell catalysis achieved 94.9% in 6 h, and the productivity given in our system was 28.2 g (L h)?1, which was higher than the productivity that had been reported. A catalysis-extraction circulation process for the synthesis ofl-alanine was established based on high-density fermentation, and the wastewater generated by this process was less than 34% of that by the fermentation process. Our results not only established a new green manufacturing process forl-alanine production fromcis-butenedioic anhydride but also provided a promising strategy that could consider both catalytic ability and cell growth burden for multi-enzyme cascade catalysis.
