Synthesis and investigation of
bacterial effector molecules
Michael Franz Albers
Akademisk avhandling
som med vederbörligt tillstånd av Rektor vid Umeå universitet för
avläggande av filosofie doktorsexamen framläggs till offentligt försvar
vid Kemiska institutionen, Umeå universitet, KBC-huset, KB3A9,
fredagen den 19 februari, kl. 10:00.
Avhandlingen kommer att försvaras på engelska.
Fakultetsopponent: Professor Dr Christian Hackenberger
Chemical Biology, Leibniz-Institut für Molekulare Pharmakologie
(FMP), Berlin (Germany)
Kemiska institutionen/Department of Chemistry
Umeå universitet/Umeå University
Umeå 2016
Organization
Document type
Date of publication
Umeå University
Department of Chemistry
Doctoral thesis
19 February 2016
Author
Michael Franz Albers
Title
Synthesis and investigation of bacterial effector molecules
Abstract
During infections, bacterial microorganisms initiate profound interactions with mammalian host
cells. Usually defense mechanisms of the host destroy intruding bacteria in rapid manner. However,
many bacterial pathogens have evolved in a way to avoid these mechanisms. By use of effector
molecules, which can be small organic molecules or proteins with enzymatic activity, the host is
manipulated on a molecular level. Effectors mediating post-translational modifications (PTMs) are
employed by many pathogens to influence the biological activity of host proteins. In the presented
thesis, two related PTMs are investigated in detail: Adenylylation, the covalent transfer of an
adenosine
monophosphate
group
from
adenosine
triphosphate
onto
proteins,
and
phosphocholination, the covalent transfer of a phosphocholine moiety onto proteins. Over the past
years, enzymes mediating these modifications have been discovered in several pathogens, especially
as a mechanism to influence the signaling of eukaryotic cells by adenylylating or phosphocholinating
small GTPases. However, the development of reliable methods for the isolation and identification of
adenylylated and phosphocholinated proteins remains a vehement challenge in this field of
research. This thesis presents general procedures for the synthesis of peptides carrying adenylylated
or phosphocholinated tyrosine, threonine and serine residues. From the resulting peptides, monoselective polyclonal antibodies against adenylylated tyrosine and threonine have been raised. The
antibodies were used as tools for proteomic research to isolate unknown substrates of adenylyl
transferases from eukaryotic cells. Mass spectrometric fragmentation techniques have been
investigated to ease the identification of adenylylated proteins. Furthermore, this work presents a
new strategy to identify adenylylated proteins. Additionally, small effector molecules are involved in
the regulation of infection mechanisms. In this work, the small molecule LAI-1 (Legionella
autoinducer 1) from the pathogen Legionella pneumophila, the causative agent of the Legionnaire’s
disease, was synthesised together with its amino-derivatives. LAI-1 showed are a clear
pharmacological effect on the regulation of the life cycle of L. pneumophila, initiating transmissive
traits like motility and virulence. Furthermore, LAI-1 was shown to have an effect on eukaryotic cells
as well. Directed motility of the eukaryotic cells was significantly reduced and the cytoskeletal
architecture was reorganised, probably by interfering with the small GTPase Cdc42.
Keywords
chemical biology, organic synthesis, bacterial effectors, PTM, nucleotidylylation
Language
English
ISBN
978-91-7601-411-0
Number of pages
110 + 7 papers