Investigation of Anthranilate Synthase Structures by Mass Spectrometry

• Applicant: Dr. Florian Busch
• Subject Area: Biochemistry ; Structural Biology
• Term: from 2017 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 347212205

The function of proteins is inevitably linked to their three-dimensional structures, which are in most cases solved by X-ray crystallography. The crystallization process, however, is inevitably associated with the formation of artificial protein-protein interactions (crystal contacts), and it is difficult in many cases to clearly differentiate those from physiologically relevant protein-protein interactions. A prominent example for such ambiguity is the anthranilate synthase, an enzyme complex that catalyzes the first step with the tryptophan biosynthetic pathway. Based on X-ray crystallographic data, homologues of the anthranilate synthase family were unexpectedly reported to differ significantly in their quaternary structures. This work aims to verify or disprove these differences by analyzing the structures of several anthranilate synthases by a complementary structural biology approach using mass spectrometry (MS) based techniques. Anthranilate synthase structures will be investigated by native MS, in addition to chemical probing approaches and subsequent MS under denaturing conditions. Besides the analysis of the quaternary structure of different anthranilate synthases, this work will also provide insights into the conformational changes that accompany the binding of the feed-back inhibitor L-tryptophan. A detailed knowledge of the structures of anthranilate synthase with and without L-tryptophan is expected to drive the development of specific antibiotics and herbicides that inhibit the growth of micro-organisms and plants. Importantly, the proposed MS-based structural biology approach is widely applicable and can guide the identification of physiological relevant protein-protein interactions as well as ligand-induced conformational changes in a multitude of cases.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professorin Dr. Vicki Wysocki