We are a young research group led by Karla Feijs and Roko Žaja. We are aiming to get a better understanding of ADP-ribosylation through different research approaches. Get in touch if you think you would like to join us!


Karla L.H. Feijs ORCID
As a master student in the lab of René Bernards at the Netherlands Cancer Institute in Amsterdam, I studied regulation of the Notch signalling pathway by ubiquitination and became fascinated by the fact that protein modifications can drive complex (patho-)physiological processes. Subsequently, during my PhD studies under supervision of Bernhard Lüscher at the RWTH Aachen University, I studied a different post-translational modification named mono(ADP-ribosyl)ation and focused mostly on the ADP-ribosyltransferase PARP10. As an EMBO Postdoctoral Fellow in Ivan Ahels laboratory at the Sir William Dunn School of Pathology in Oxford, I then studied the reversal of mono(ADP-ribosyl)action by MacroD1, MacroD2 and TARG1. Following a year and a half maternity break I returned to RWTH Aachen University to set up my own research group at the end of 2017 for only a few months. Following another maternity break, I started full-time work again early 2019.

Roko Žaja ORCID
Roko performed his undergraduate studies at the Josip Juraj Strossmayer University in Osijek, Croatia, followed by a period of civil service and volunteering. His graduate studies he performed at the Rudjer Boskovič Institute in Zagreb with Tvrtko Smital, where he focused mostly on ABC-transporters. He then spent 3 years as a postdoc in Ivan Ahel’s group working on ADP-ribosylation in the DNA damage response. After a period of part-time work due to childcare, he is full-time group leader since 2020 at the Institute of Biochemistry and Molecular Biology of RWTH Aachen University.

Lisa Weixler – PhD student
Already at the beginning of my bachelor’s studies I decided to specialise on biochemistry and biomedicine. At the Max Planck Institute (MPI) for Biology of Ageing in Cologne, in the laboratory of Prof. Dr. Larsson, and within my bachelor’s thesis period at the Center national de la recherche scientifique (CNRS) in France, I investigated the regulation mechanisms of the mitochondrial RNA polymerase POLRMT in vitro and in vivo. My master’s thesis project at Boehringer Ingelheim, Department of Medicinal Chemistry, addresses the structural, biochemical and biophysical investigation of the GTP cyclohydrolase I (GTPCH-I), to gain insights into potential drug candidates and the underlying disease mechanisms of GTPCH-I genetic defects. Currently I am investigating biochemical aspects of the posttranslational modification mono(ADP-ribosyl)ation as topic of my PhD project at the RWTH Aachen University Hospital.

Nonso Ikenga – PhD student
Nonso has received his B.Sc. from the University of Nigeria in Nsukka, Nigeria, and his M.Sc. from Universität Würzburg in Germany. For his master thesis, he characterised a novel DEAD box RNA helicase from Trypanosoma brucei under supervision of Susanne Kramer. He has joined our group to investigate cellular processes regulated by ADP-ribosylation.

Tarek Elsayed – PhD student

Tarek did his bachelor’s studies at Fayoum University in Egypt. Then, he decided to specialize in biochemistry and cancer biology. He worked at the National cancer institute of Egypt as a research engineer to study the role of some proteins and miRNAs in the resistance of liver cancer patients. He got a scholarship from the French embassy in Egypt to do master studies in Paris at  PSL university in the program of “Life sciences and Cancer biology”. He continued his studies and obtained another Master’s degree from Université Paris-Saclay in the program of “Systems and synthetic biology”. During his master’s degree, he worked at Gustave Roussy cancer institute in Paris in the group of Prof. Dr. Alexander Ishchenko who was focusing on studying PARP proteins and their DNA modification ability.  Tarek investigated the basic characters of two proteins as readers and erasers of the PARP modification in vitro and in vivo. Currently, he joined our group to characterize the mono(ADP-ribosyl)transferases and their role in antiviral immunity during his Ph.D. project at the RWTH Aachen University Hospital.

Gülcan Aydin – Technician
Gülcan works since January 2010 in the Uniklinik Aachen as technician. In her first job in the Department of Cell Biology (AG Prof Zenke) she gained experience in cell and molecular biology and was integrated in several scientific projects. In March 2018 she joined our lab at the Institute of Biochemistry and Molecular Biology.

Maria Backhaus – MSc student
I am currently doing my Master’s degree in biotechnology at the FH Aachen. In my bachelor thesis, I studied the effects of the loss of various genes involved in DNA damage repair on the development and lethality of C. elegans at the CECAD in Cologne. Thereby, I found it fascinating what a huge impact the loss of a single enzyme can have on an organism. Motivated by this, I wanted to find out what effect the loss of enzymes whose function is still largely unknown has on human cells. Therefore, I joined the FeZa lab for my master’s thesis, where I try to unravel the impact of different stressors on knockout cell lines.

Lennart Lindner – MSc student
I am a physics student at RWTH Aachen. In my Bachelor Thesis I characterised the strength of high affinity bindings using a confocal microscope setup in the Biophysics group at RWTH Aachen. Interested in learning Biochemical techniques and working interdisciplinary, I have joined the FeZa lab for my Master Thesis. I will study how selected members of the PARP family are activated.

Dariia Plaksina – BSc student/student assistant

Dariia is studying Biology at the Taras Shevchenko National University of Kyiv and is performing her practical studies in the FeZa lab. She is learning a range of molecular and cell biology methods and is helping with establishing some new cell lines.


Timo Bolte – MSc student 2021-2022

Katja Schäringer – PhD student 2020 (co-supervised with Bernhard Lüscher)
current Springer Medizin, München, Germany

Kaiseng Quach – Student assistant 2018/2020
current medical student at RWTH Aachen

Petra Toneva – BSc student 2020/2021
current technician at Alvotech

Jeffrey Momoh, MSc student 2020 (Staffordshire University)
current PhD student at the Department of Nanomedicine and Theranostics, RWTH Aachen

Thore Diefenbach, BSc student 2019 (RWTH Aachen)
current MSc student at University of Natural Resources and Life Sciences, Vienna

Jessica Malcev, MSc student 2019 (Maastricht University)
current Head of Manufacturing, Cellex Cell Professionals

Sandro Capellmann, MSc student 2018 (RWTH Aachen)
current PhD student at the Institute of Biochemistry and Molecular Immunology

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