EMBL Hamburg News
Pupylation targets identified in Mycobacteria
A proteome wide analysis of Mycobacterium smegmatis revealed 41 validated candidate pupylation targets
In a paper published today in Molecular Systems Biology, scientists from EMBL Hamburg report on their work on identifying post-translational targets in Mycobacteria. A proteome wide analysis of Mycobacterium smegmatis revealed a total of 41 validated candidate targets using two complementary proteomics approaches.
The genus Mycobacteria consists of several pathogenic bacteria known to be fatal for humans and animals such as Mycobactierum tuberculosis (Tuberculosis), and M. leprae (Leprosy). In order to develop new approaches for combating these diseases, a full understanding of the disease mechanism is needed. The recent sequencing of the complete Mycobactierum tuberculosis (MTb) genome and proteome has enabled more research in this area, however relatively little is still known about post-translational modification of proteins in M. tuberculosis.
Whereas post-translational modification of proteins in Eukaryotes may be attributed to the protein Ubiquitin, in Mycobacteria this is done by the conjugation of a small protein, referred to as a prokaryotic ubiquitin-like protein, or PUP. Although this process has attracted much interest in recent years, only a few possible PUP targets have been identified to date. The project started when two graduate students from EMBL-Hamburg, Christian Poulsen and Yusuf Akhter, observed that PUP from M. tuberculosis co-purifies in the presence of various other proteins when expressed in the model organism M. smegmatis. In order to understand the impact of this process on the function of mycobacterial biology, Matthias Wilmanns and his group at EMBL Hamburg undertook a proteome wide analysis of M. smegmatis. Using two complementary proteomics approaches, in collaboration with the research groups of Gerold Schmitt-Ulms (Toronto, Canada) and Kai Stuehler (Bochum, Germany), the EMBL team observed a total of 48 pupylation sites in the M. smegmatis proteome. Many of these targets also have orthologous genes in Mycobacteria tuberculosis involved in key pathways such as intermediary metabolism and respiration. The scientists at EMBL Hamburg have shown that a substantial number of proteins may serve as targets for modification by PUP conjugation. “The next step is to map the available evidence onto the M. tuberculosis proteome, and that of other pathogenic Mycobacteria” says Wilmanns, “we are also interested in finding out just how, and to what extent, pupylation of targets varies during the mycobacterial life cycle, and in the host environment. We hope this will lead us to new applications in the fight against Tuberculosis and other mycobacterial diseases.”