Biology subjects

Jayaraj, A.

Publications and source records attributed to Jayaraj, A..

3 recordsLinked to original sources

bioRxiv2026

ssDNA hand-off from RPA to Polθ drives microhomology-mediated end-joining

DNA polymerase theta-mediated end joining (TMEJ) is the primary mechanism of double strand break repair in mitosis and becomes essential in BRCA-deficient cells. RPA, the ssDNA-binding protein that coats resected DNA ends, has long been thought to inhibit this pathway by blocking the initial microhomology search in TMEJ. Here we find instead that RPA plays an essential activating role in TMEJ. Structural, biochemical, and genetic analyses support a model in which Pol{theta} binds directly to RPA at resected DNA ends and then competes with RPA for ssDNA. This releases ssDNA into the Pol{theta} helicase domain. We propose that threading two DNA ends through the Pol{theta} dimer in this manner initiates the search for microhomology. Together, our findings establish a detailed mechanism of how proteins can harness RPA to access ssDNA for critical genome maintenance transactions.

biochemistry↗

bioRxiv2024

Ergothioneine boosts mitochondrial respiration and exercise performance via direct activation of MPST

Ergothioneine (EGT) is a diet-derived, atypical amino acid that accumulates to high levels in human tissues. Reduced EGT levels have been linked to age-related disorders, including neurodegenerative and cardiovascular diseases, while EGT supplementation is protective in a broad range of disease and aging models in mice. Despite these promising data, the direct and physiologically relevant molecular target of EGT has remained elusive. Here we use a systematic approach to identify how mitochondria remodel their metabolome in response to exercise training. From this data, we find that EGT accumulates in muscle mitochondria upon exercise training. Proteome-wide thermal stability studies identify 3-mercaptopyruvate sulfurtransferase (MPST) as a direct molecular target of EGT; EGT binds to and activates MPST, thereby boosting mitochondrial respiration and exercise training performance in mice. Together, these data identify the first physiologically relevant EGT target and establish the EGT-MPST axis as a molecular mechanism for regulating mitochondrial function and exercise performance.

molecular biology↗

bioRxiv2024

Structural Insights into the DNA-Binding Mechanism of BCL11A: The Integral Role of ZnF6

The transcription factor BCL11A is a critical regulator of the switch from fetal hemoglobin (HbF: 2{gamma}2) to adult hemoglobin (HbA: 2{beta}2) during development. BCL11A binds at a cognate recognition site (TGACCA) in the {gamma}-globin gene promoter and represses its expression. DNA-binding is mediated by a triple zinc finger domain, designated ZnF456. Here, we report comprehensive investigation of ZnF456, leveraging X-ray crystallography and NMR to determine the structures in both the presence and absence of DNA. We delve into the dynamics and mode of interaction with DNA. Moreover, we discovered that the last zinc finger of BCL11A (ZnF6) plays a special role in DNA binding and {gamma}-globin gene repression. Our findings help account for some rare {gamma}-globin gene promoter mutations that perturb BCL11A binding and lead to increased HbF in adults (hereditary persistence of fetal hemoglobin). Comprehending the DNA binding mechanism of BCL11A opens avenues for the strategic, structure-based design of novel therapeutics targeting sickle cell disease and {beta}-thalassemia.

molecular biology↗