Functions and properties of citrate lyase beta-subunit-like proteins

• Applicant: Professor Dr. Ivan A. Berg
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2011 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 208327442

The function of many proteins encoded in the genomes is unknown even for best studied model organisms like Corynebacterium glutamicum, Pseudomonas aeruginosa or Salmonella enterica. Using purified proteins, we have recently shown that a citrate lyase ß-subunit-like (CitE-like) protein in Yersinia pestis and P. aeruginosa functions as (S)-citramalyl-CoA lyase in itaconate metabolism. Our results revealed the connection of itaconate degradation to pathogenicity and suggested that itaconate degradation can be regarded as a persistence factor in various pathogens. Now, we want to transfer our in vitro model of itaconate degradation obtained with heterologously produced Y. pestis enzymes into the in vivo studies of Salmonella cells grown on minimal media with itaconate as well as during infection. Furthermore, our preliminary data suggest functional diversity of proteins of CitE family: mycobacterial and halobacterial CitE catalyze (R)-3-hydroxy-3-methylglutaryl-CoA lyase reaction in a novel leucine degradation pathway; C. glutamicum CitE functions as malyl-CoA thioesterase, and other CitE proteins apparently have different functions in metabolism. In this project, we are going (i) to study the importance of itaconate degradation for pathogenesis using Salmonella enterica serovar Typhimurium as a model organism both in vitro and in vivo in a mouse model (in collaboration with Prof. Wolf-Dietrich Hardt, Zurich); (ii) to reveal details of a novel leucine degradation pathway; (iii) to test the hypothesis of the involvement of C. glutamicum CitE in metabolic proofreading (in collaboration with Prof. Michael Bott, Julich); (iv) to study functions of CitE proteins in other microorganisms, and (v) to perform structural studies in order to understand molecular bases for the substrate specificity of these enzymes (in collaboration with Dr. Ulrich Ermler, Frankfurt).

• DFG Programme: Research Grants