6kcr
From Proteopedia
X-ray structure of the MtlR-HPr complex from Escherichia coli
Structural highlights
Function[MTLR_ECOLI] Involved in the repression of the expression of the mannitol mtlADR operon (PubMed:8300537). Does not bind the operator/promoter regulatory region of this operon (PubMed:19840941). Therefore, seems to belong to a new class of transcription factors in bacteria that may regulate gene expression indirectly, perhaps as a part of a larger transcriptional complex.[1] [2] [PTHP_ECOLI] General (non sugar-specific) component of the phosphoenolpyruvate-dependent sugar phosphotransferase system (sugar PTS). This major carbohydrate active-transport system catalyzes the phosphorylation of incoming sugar substrates concomitantly with their translocation across the cell membrane. The phosphoryl group from phosphoenolpyruvate (PEP) is transferred to the phosphoryl carrier protein HPr by enzyme I. Phospho-HPr then transfers it to the permease (enzymes II/III). Publication Abstract from PubMedCarbon catabolite repression is a regulatory mechanism to ensure sequential utilization of carbohydrates and is usually accomplished by repression of genes for the transport and metabolism of less preferred carbon compounds by a more preferred one. Although glucose and mannitol share the general components, enzyme I and HPr, of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) for their transport, glucose represses the transport and metabolism of mannitol in a manner dependent on the mannitol operon repressor MtlR in Escherichia coli. In a recent study, we identified the dephosphorylated form of HPr as a regulator determining the glucose preference over mannitol by interacting with and augmenting the repressor activity of MtlR in E. coli. Here, we determined the X-ray structure of the MtlR-HPr complex at 3.5 A resolution to understand how phosphorylation of HPr impedes its interaction with MtlR. The phosphorylation site (His15) of HPr is located close to Glu108 and Glu140 of MtlR and phosphorylation at His15 causes electrostatic repulsion between the two proteins. Based on this structural insight and comparative sequence analyses, we suggest that the determination of the glucose preference over mannitol solely by the MtlR-HPr interaction is conserved within the Enterobacteriaceae family. Structural insight into glucose repression of the mannitol operon.,Choe M, Min H, Park YH, Kim YR, Woo JS, Seok YJ Sci Rep. 2019 Sep 26;9(1):13930. doi: 10.1038/s41598-019-50249-2. PMID:31558743[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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