Biology subjects

Lopez, V. A.

Publications and source records attributed to Lopez, V. A..

3 recordsLinked to original sources

bioRxiv2026

TIR-like NADases act in bacterial immunity and the RNA vault

Across all domains of life, organisms exploit NAD+ metabolism as a central line of defense against invading pathogens. Here, we show that domain of unknown function 4062 (DUF4062) is a widespread family of TIR-like NADases that hydrolyze NAD+ to ADP-ribose and nicotinamide. In bacteria, DUF4062 homologs form a previously unrecognized antiphage defense system, which we name Swaro[z]yc, that assembles with the phage portal into a supramolecular NADase complex to induce abortive infection. In eukaryotes, DUF4062 is found in TEP1, which we demonstrate functions as an active NADase within the RNA vault, an enigmatic organelle-like structure. Single-particle cryo-electron microscopy reveals ADP-ribose bound within the shoulder of both reconstituted and human brain vaults, while cryo-electron tomography positions TEP1 along the central axis at the shoulder. Thus, TEP1, like bacterial Swaro[z]yc, functions by depleting NAD+, providing new insight into the long-standing mystery of vault function.

biochemistry↗

bioRxiv2025

ACAD10 encodes two orphan enzymes in the ether lipid biosynthetic and salvage pathways

Ether lipids play critical roles in membrane dynamics, antioxidant defense, and signaling. They comprise ~20% of mammalian phospholipids, and disruptions in their metabolism cause severe genetic disorders and are associated with neurodegenerative and metabolic diseases. Ether lipids are synthesized de novo from glycolytic intermediates or salvaged from the diet. While the products of these pathways are known, several key enzymes remain unidentified, including the 1-O-alkylglycerol kinase and the 1-O-alkyl-2-acetyl-sn-glycero-3-phosphate phosphatase. Here, we show that acyl-CoA dehydrogenase member 10 (ACAD10) catalyzes the phosphorylation of 1-O-alkylglycerols and the dephosphorylation of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphate. Worms and mice lacking ACAD10 have reduced ether lipid levels and cannot salvage dietary alkylglycerols. Furthermore, individuals from the Akimel O'odham (Pima) tribe carrying ACAD10 polymorphisms also show decreased plasma ether lipid levels. Collectively, our findings resolve two long-standing gaps in ether lipid biochemistry and reveal a mechanistic link between ether lipid metabolism and a population-associated risk factor for type 2 diabetes.

biochemistry↗

bioRxiv2024

Biochemical and structural insights into a 5' to 3' RNA ligase reveal a potential role in tRNA ligation

ATP-grasp superfamily enzymes contain a hand-like ATP-binding fold and catalyze a variety of reactions using a similar catalytic mechanism. More than 30 protein families are categorized in this superfamily, and they are involved in a plethora of cellular processes and human diseases. Here we identify C12orf29 as an atypical ATP-grasp enzyme that ligates RNA. Human C12orf29 and its homologs auto-adenylate on an active site Lys residue as part of a reaction intermediate that specifically ligates RNA halves containing a 5-phosphate and a 3-hydroxyl. C12orf29 binds tRNA in cells and can ligate tRNA within the anticodon loop in vitro. Genetic depletion of c12orf29 in female mice alters global tRNA levels in brain. Furthermore, crystal structures of a C12orf29 homolog from Yasminevirus bound to nucleotides reveal a minimal and atypical RNA ligase fold with a unique active site architecture that participates in catalysis. Collectively, our results identify C12orf29 as an RNA ligase and suggest its involvement in tRNA biology. Significance StatementATP-grasp enzymes share an atypical ATP-binding fold and catalyze a diverse set of reactions involved in many essential cellular processes. We identified C12orf29 as an atypical ATP-grasp enzyme. Our biochemical and structural characterizations reveal this enzyme to be a 5 to 3 RNA ligase, structurally and functionally similar to the phage T4 RNA ligase. C12orf29 can ligate tRNAs in vitro and C12orf29 knockout female mice have altered tRNA levels in brain. We also report structures of C12orf29, which have revealed critical insights into the mode of ATP binding and catalysis. Our work suggests that C12orf29 may be a new player in the regulation of tRNAs.

biochemistry↗