eprintid: 16019
rev_number: 12
eprint_status: archive
userid: 433
dir: disk0/00/01/60/19
datestamp: 2014-01-13 07:59:40
lastmod: 2014-02-27 11:31:11
status_changed: 2014-01-13 07:59:40
type: doctoralThesis
metadata_visibility: show
creators_name: Trinh, Dinh-Van
creators_name: Dinh-Van, Trinh
title: Missing links of the protein Nα-terminal
acetylation machinery in plants
subjects: 570
divisions: 721000
adv_faculty: af-14
abstract: Protein N-terminal acetylation (Nt-acetylation) is the transfer of acetyl group from acetyl
coenzyme A (Ac-CoA) to the alpha amino acid of a protein. Since it has been discovered
more than fifty years ago, Nt-acetylation is known to be one of the most common protein
modifications in eukaryotes, occurring on approximately 50-70% of yeast soluble protein
and about 80-90% of human protein. However, the exact biological role has remained
enigmatic for majority of affected proteins, and only for a small number of proteins, Ntacetyation
was linked to various features of protein such as localization, stability and
interaction. Nt-acetylation in yeast and in human is thoroughly investigated with the
identification of five (NatA-NatE) and six (NatA-NatF) Nα-acetyltransferase (NAT) types,
respectively. In contrast, the knowledge of Nt-acetylation in plants was vacant for many
years. The first Arabidopsis NAT, AtNatC was identified in 2003, and very recently three
more NATs (NatA, NatB and NatE) were described by Iwona Stephan. In this study, we
identified two NATs (NatD and NatF) that are still missing in plants. AtNatD/AtNaa40p is
conserved from yeast with respect to acetylation of protein histone H4. The lack of Nterminal
serine acetylation increases the overall positive charge of H4 N-tail which causes
the minor phenotypes observed in atnaa40 mutant. The acetylation of N-terminal serine of
histone H4 might also involve in DNA double-strand break response. Besides, the
subcellular localization to cytoplasm and nucleus suggests a lysine acetyltransferase
activity of AtNaa40p towards histones. AtNatF/AtNaa60 unusually localizes to plasma
membrane and to the tonoplast. The sensitivity of atnaa60 mutant to salt tress during
germination stage appears to be related to the localization, and indicating the involvement
of AtNaa60p in salt stress or osmotic stress response. Like hNaa60p, AtNaa60 is believed
to acetylate a large number of proteins according to the NBD-Cl fluorescent assay.
AtNaa60p acetylates methione and serine starting peptides in vitro.
In addition, numerous proteins are found N-terminally acetylated in chloroplasts, both
chloroplast-encoded and nuclear-encoded proteins. In silico study reveals eight putative
plastidic NATs of which seven localize to the chloroplasts when they are transiently
expressed with EYFP in Arabidopsis protoplasts. Three proteins (At2g39000, At1g24040
and At2g06025) acetylate plenty of Escherichia coli proteins, their substrate specificities
are strongly correlated to chlotoplast transit peptide (cTP) cleavage sites. Four other
proteins (At4g19984, At1g26220, At1g32070 and At4g28030) are possibly true NATs
since they possess the conserved Ac-CoA binding motif. Our results, together with other
studies on acetylation in chloroplast, propose the connection between Nt-acetylation of
chloroplastic proteins and drought stress.
date: 2013
id_scheme: DOI
id_number: 10.11588/heidok.00016019
ppn_swb: 1653439777
own_urn: urn:nbn:de:bsz:16-heidok-160196
date_accepted: 2013-12-16
advisor: HASH(0x556120c2b580)
language: eng
bibsort: TRINHDINHVMISSINGLIN2013
full_text_status: public
citation:   Trinh, Dinh-Van ; Dinh-Van, Trinh  (2013) Missing links of the protein Nα-terminal acetylation machinery in plants.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/16019/1/Trinh%20-%20Dissertation.pdf