title: The Nα-acetyltransferase NAA50 regulates fertility and stress responses in Arabidopsis thaliana
creator: Armbruster, Laura
subject: ddc-570
subject: 570 Life sciences
subject: ddc-580
subject: 580 Botanical sciences
description: Even though Nα-terminal acetylation (NTA) is conserved throughout the three domains of life, knowledge about its biological function remains limited. In Arabidopsis thaliana, NTA affects up to 80 % of all soluble cytosolic proteins and is catalyzed by a set of Nα-terminal  acetyltransferases (NatA-G). AtNatA is the major Nat complex and targets approximately 40 % of the plant proteome. The core AtNatA complex consists of the catalytic subunit AtNAA10 and the ribosome-binding subunit AtNAA15.  In humans, this complex associates with the regulatory subunits HsNAA50 and HsHYPK to form the quaternary HsNatA/E complex. Recently, homologs of NAA50 (AT5G11340) and HYPK (AT3G06610) were identified in A. thaliana. While AtHYPK is tethered to the core AtNatA complex and modulates its activity, the interaction of AtNAA50 with AtNatA is still controversially discussed.    This work provides evidence for the association of AtNAA50 with the core AtNatA components and the ribosome. AtNAA50 was found in the proximity of AtNAA10, AtNAA15 and AtHYPK in vivo. Co-immunoprecipitation experiments independently confirmed these findings and suggested novel potential binding partners of AtNAA50.    Unlike AtHYPK, AtNAA50 did not modulate AtNatA activity. This was evidenced by the absence of significant shifts in the NTA yield of known NatA substrates in NAA50-depleted mutants. In line with this finding, the depletion of AtNAA50 did not impact NatA-mediated proteome stability, either. Nevertheless, AtNAA50 seemed to exert a critical NatA-independent biological function since its knockout resulted in severe growth retardation and infertility.    The generation of aminaa50 knockdown mutants revealed that minimal amounts of AtNAA50 were sufficient to ensure proper plant growth. Global transcriptome and proteome analyses of the mutants showed that the depletion of AtNAA50 caused a constitutive upregulation of the plant defense response against pathogens. In line with this finding, aminaa50 plants were resistant to the bacterium Pseudomonas syringae. However, the abundance of phytohormones that usually trigger this resistance was not increased in aminaa50. Apart from its role in vegetative growth and the regulation of plant defense, complementation studies suggested that NAA50 was required for pollen formation.    In summary, this thesis demonstrates that even though AtNAA50 interacted with the core AtNatA complex, it executed functions beyond regulating AtNatA activity.
date: 2022
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/31717/1/Armbruster-2022.pdf
identifier: DOI:10.11588/heidok.00031717
identifier: urn:nbn:de:bsz:16-heidok-317176
identifier:   Armbruster, Laura  (2022) The Nα-acetyltransferase NAA50 regulates fertility and stress responses in Arabidopsis thaliana.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/31717/
relation: WI 3560/4–1
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng