Struktur- und Funktionsanalysen von pilzlichen Zellwandproteinen der SUN- und CFEM-Proteinfamilien
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Date
2018-08-08
Authors
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Philipps-Universität Marburg
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Abstract
The fungal kingdom is one of the most diverse lifeforms found on earth. Hereby the manifold number
of different subspecies reflects their populated ecological niches. The fungal cell wall is a complex
and highly functional organelle that allows adaptation to adverse environmental conditions like
change in osmolarity. This 50 – 200 nm thick layer is formed by a basic set-up from chitin and b-
1,3-/ b-1,6-glucans and further species specific content. Within this heavily cross-linked network the
b-1,3-glucans form triple helical structures that are then linked to the chitin moiety. This corecontent
of b-glucans and chitin is primarily responsible for the robustness of the fungal cell wall. In
the cross–linked space of the inner cell wall an enormous number of secreted proteins perform various
roles.
This work will focus on the two groups of SUN- and CFEM-proteins. SUN-proteins play a role during
the cell wall remodelling process of b-1,3-glucans. SPR and HDX-MS experiments for the Cterminal
SUN-domain of Saccharomyces cerevisiae showed active binding towards Laminarin, a b-1,3-
glucan with additional b-1,6-glucose linkage [7:1]. Molecular dynamic simulations of ScSun4C with
bound curdlan, an unlinked triple helical b-1,3-glucan, showed stable binding during the whole calculation
of 100 ns. These binding results combined with structural information of the C-terminal
SUN-domain lead to two hypothetical models. The SUN-domain as a novel, reversible b-glucan
docking unit or as a triple helical b-glucan unwinding domain. This glucan helicase like behaviour
unwinds hereby the triple helical form and passes one single b-glucan strand through its tunnel. This
single b-glucan then can be easily hydrolysed by endo-/exo-glucanase. Atomic force microscopy could
verify this glucan helicase functionality
CFEM-Proteins show in phylogenetic analysis distinct groups with cluster specific functions. That is
in accordance with structural information from the protein structure of Candida albicans Csa2 a
Pga7-like protein. This group of Pga7-like proteins is involved in heme-iron acquisition from haemoglobin
and the transport inside the cell. A time dependent heme binding mechanism could be observed
for Pga-like proteins with a two-step binding mode and a structural reorganisation within the
binding pocket. Ccw14-like CFEM-proteins lack the heme-binding functionality. This group plays a
role in cross-linking the inner cell wall compartment. The interaction of Ccw14 from Saccharomyces
cerevisiae with Bgl2, an endo-glucanase could solve the mystery about this group.
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Dates
Created: 2017Issued: 2018-08-08Updated: 2018-08-08
Faculty
Fachbereich Chemie
Language
ger
Data types
DoctoralThesis
Keywords
SUNbiochemistryb-1,3-GlukanSUNfungal cell wallGlukanhelikasepilzliche ZellwandtriplehelixProteinGlukosidaseThaumatin-Domäne,glucosidaseCFEMb-1,3-GlucanCFEMRemodellierungproteinglucan helicaseglucan dockingTripelhelixthaumatin-fremodellingDockingBiochemie
DDC-Numbers
570
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Kalugin, Vitali: Struktur- und Funktionsanalysen von pilzlichen Zellwandproteinen der SUN- und CFEM-Proteinfamilien. : Philipps-Universität Marburg 2018-08-08. DOI: https://doi.org/10.17192/z2017.0509.