Crystallization and structural analysis of three transcriptional regulators from eubacteria and archaea: Aes. Mlc and TrmB

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We propose to crystallize and determine the three-dimensional structure of procaryotic transcription factors and proteins that are interacting with these regulators, that control their activity and couple this control to metabolic signal transduction chains. The frist protein is Aes from E. coli. It is an enzyme with acetyl esterase activity that exhibits homology to the family of hormone-sensitive lipases. The interest in this enzyme is based on its demonstrated interaction with MalT, the contral regulator of the E. coli maltose system. The second transcription regulator is Mlc, a global transcriptional repressor controlling the expression of the malT gene and in addition a number of genes encoding some specific proteins (for glucose and mannose) and all general enzymes of the E. coli phosphotransferase system (PTS). The interest in Mlc comes from its unusual mode of inactivation by sequestration to the PtsG transproter. We plan to determine the structure of Mlc als well as of the complex of Mlc with the soluble EIIB domain of PtsG. The third transcription regulator is TrmB, a sugar-specific transcription repressor controlling the genes encoding a high affinity and binding protein-dependent ABC transproter for trehalose and maltose in the hyperthermophilic archaeon Thermococcus litoralis. The interest in this regulator comes from the fact that is ist the first identified sugar specific regulator of archaea acting on a transcription machinery of eucaryotic relateness. The goal of this proposal is aimed at the understanding of a novel type of transcriptional regulation in which the regulator is controlled by direct protein-protein interaction.