Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States.
Published: November 2023
AI Article Synopsis
Article Abstract
Methylthiotransferases (MTTases) are radical -adenosylmethionine (SAM) enzymes that catalyze the addition of a methylthio (-SCH) group to an unreactive carbon center. These enzymes are responsible for the production of 2-methylthioadenosine (msA) derivatives found at position A37 of select tRNAs in all domains of life. Additionally, some bacteria contain the RimO MTTase that catalyzes the methylthiolation of the S12 ribosomal protein. Although the functions of MTTases in bacteria and eukaryotes have been established via detailed genetic and biochemical studies, MTTases from the archaeal domain of life are understudied and the substrate specificity determinants of MTTases remain unclear. Here, we report the enzymatic activities of an MTTase (C4B56_06395) from a thermophilic Methanophagales anaerobic methanotroph (ANME) as well as the MTTase from a hyperthermophilic methanogen - MJ0867 from . Both enzymes catalyze the methylthiolation of -threonylcarbamoyladenosine (tA) and hydroxynorvalylcarbamoyladenosine (hnA) residues to produce 2-methylthio--threonylcarbamoyladenosine (mstA) and 2-methylthio-hydroxynorvalylcarbamoyladenosine (mshnA), respectively. To further assess the function of archaeal MTTases, we analyzed select tRNA modifications in a model methanogen - - and generated a deletion of the MTTase-encoding gene (MA1153). We found that produces mshnA in exponential phase of growth, but does not produce mstA in detectable amounts. Upon deletion of MA1153, the msA modification was absent, thus confirming the function of MtaB-family MTTases in generating mshnA modified nucleosides in select tRNAs.
Background: As the primary organ of metabolism and detoxification, the liver may contribute to the pathogenesis of lung cancer. We aimed to illuminate the intricate link between liver function biomarkers and lung cancer risk, as well as delineate the role of smoking behavior within this association.
Methods: We investigated the associations of seven liver function biomarkers levels (alkaline phosphatase [ALP], alanine transaminase [ALT], total bilirubin [TBIL], albumin [ALB], gamma-glutamyltransferase [GGT], aspartate transaminase [AST], and total protein [TP]) with lung cancer risk across the UK Biobank (N = 337 499) through restricted cubic splines and Cox proportional hazards models.
D-Allulose 3-epimerase catalyzes C-3 epimerization between D-fructose and D-allulose was found in strain M30. The enzyme gene was cloned, and its recombinant enzyme and the mutant variants were expressed in Using the information of the sequence and model structure, we succeed in the improvement of melting temperature for the enzyme without significant loss of the enzyme activity by protein engineering method. The melting temperatures were increased by 2.
Laboratory Medicine Center, Department of Genetic and Genomic Medicine, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China.
Background: GTPBP3 catalyzes τm(s) U biosynthesis at the 34th wobble position of mitochondrial tRNAs, the hypomodification of τmU leads to mitochondrial disease. While twenty-three variants of GTPBP3 have been reported worldwide, the genetic landscape in China remains uncertain.
Methods: By using whole-exome sequencing, the candidate individuals carrying GTPBP3 variants were screened and identified.
Hydrogen sulfide (HS) is an environmental hazard well known for its neurotoxicity. In mammalian cells, HS is predominantly generated by transsulfuration pathway enzymes. In addition, HS produced by gut microbiome significantly contributes to the total sulfide burden in the body.
Apurinic/apyrimidinic endonuclease 1 (APE1) is a central enzyme in the base excision repair (BER) pathway. APE1 catalyzes incision of the phosphodiester linkage on the 5'-side of apurinic/apyrimidinic (AP) sites during the repair of damaged nucleobases in cellular DNA. Inhibition of this enzyme can potentiate the action of DNA-damaging chemotherapeutic agents.
