Biology subjects

Kruparani, S. P.

Publications and source records attributed to Kruparani, S. P..

3 recordsLinked to original sources

bioRxiv2023

Archaeal origin translation proofreader imparts multialdehyde stress tolerance to land plants

Aldehydes, being an integral part of carbon metabolism, energy generation and signalling pathways, are ingrained in plant physiology. Land plants have developed intricate metabolic pathways which involve production of reactive aldehydes and its detoxification to survive harsh terrestrial environments. Here, we show that physiologically produced aldehydes i.e., formaldehyde and methylglyoxal in addition to acetaldehyde, generate adducts with aminoacyl-tRNAs, a substrate for protein synthesis. Plants are unique in possessing two distinct chiral proofreading systems, D-aminoacyl-tRNA deacylase1 (DTD1) and DTD2, of bacterial and archaeal origins, respectively. Extensive biochemical analysis revealed that only archaeal DTD2 can remove the stable D-aminoacyl adducts on tRNA thereby shielding archaea and plants from these system-generated aldehydes. Using Arabidopsis as a model system, we have shown that the loss of DTD2 gene renders plants susceptible to these toxic aldehydes as they generate stable alkyl modification on D-aminoacyl-tRNAs, which are recycled only by DTD2. Bioinformatic analysis identifies the expansion of aldehyde metabolising repertoire in land plant ancestors which strongly correlates with the recruitment of archaeal DTD2. Finally, we demonstrate that the overexpression of DTD2 offers better protection against aldehydes than in wild-type Arabidopsis highlighting its role as a multi-aldehyde detoxifier that can be explored as a transgenic crop development strategy.

plant biology↗

bioRxiv2020

Recruitment of Archaeal DTD is a Key Event in the Emergence of Land Plants

Land plant evolution is a major leap in the history of life that took place during the Neoproterozoic Era ([~]800 Mya). Charophyceae, a class of rhyzophytic green algae emerged as a land plant with innovations in biochemical, cytological and developmental adaptations and played a crucial role in establishing life on the land1,2. One such striking architectural innovation is "root" that experience harsh environmental assaults such as floods, waterlogging and therefore is the epicentre for anaerobic fermentation, which produces toxic acetaldehyde3. Here, we show that such produced acetaldehyde makes N-ethyl-adducts on a central component of translation machinery aa-tRNA. The Plant kingdom is unique among life forms in possessing two chirality-based proofreading systems represented by D-aminoacyl-tRNA deacylases (DTD1 and DTD2), derived from Bacteria and Archaea4. We identified a unique role of archaeal derived chiral proofreading module DTD2 that selectively deacylates N-ethyl-D-aminoacyl-tRNAs (NEDATs) in plants. NEDAT deacylase function is exclusive to DTD2, as no other proofreading modules with similar substrates like canonical DTD1 and peptidyl-tRNA hydrolase (PTH) can clear NEDATs. Thus, the study elucidates the cause of hypersensitivity of DTD2 knockout plants for both ethanol and acetaldehyde. We further show NEDAT elimination is rooted in Archaea which possess the biosynthesis machinery for ethanol fermentation similar to plants. While absent in other algal branches, DTD2 can be identified in plants from land plant ancestors-Charophytes onwards. DTD2 is the only gene that has only archaeal origin among the genes ascribed for architectural and genomic innovations that happened in the land plant ancestors. The work has uncovered an important gene transfer event from methanogenic archaea to the charophytes in the oldest terrestrial ecosystem bog that contains excess of D-amino acids and deprived of oxygen.

biochemistry↗

bioRxiv2018

A discriminator code-based DTD surveillance ensures faithful glycine delivery for protein biosynthesis in bacteria

D-aminoacyl-tRNA deacylase (DTD) acts on achiral glycine, in addition to D-amino acids, attached to tRNA. We have recently shown that this activity enables DTD to clear non-cognate Gly-tRNAAla with 1000-fold higher efficiency than its activity on Gly-tRNAGly, indicating tRNA-based modulation of DTD (Pawar et al., 2017). Here, we show that tRNAs discriminator base predominantly accounts for this activity difference and is the key to selection by DTD. Accordingly, the uracil discriminator base, serving as a negative determinant, prevents Gly-tRNAGly misediting by DTD and this protection is augmented by EF-Tu. Intriguingly, eukaryotic DTD has inverted discriminator base specificity and uses only G3*U70 for tRNAGly/Ala discrimination. Moreover, DTD prevents alanine-to-glycine misincorporation in proteins rather than only recycling mischarged tRNAAla. Overall, the study reveals the unique co-evolution of DTD and discriminator base, \"reciprocally\" in Bacteria and Eukarya, and suggests DTDs strong selection pressure on bacterial tRNAGlys to retain a pyrimidine discriminator code.

biochemistry↗