Potential Regulatory Role of Competitive Encounter Complexes in Paralogous Phosphotransferase Systems

JOURNAL OF MOLECULAR BIOLOGY

卷:431

Article

Strickland, Madeleine¹  Kale, Seyit^1,4  Strub, Marie-Paule¹  Schwieters, Charles D.²  Liu, Jian¹  Peterkofsky, Alan^3,5  Tjandra, Nico¹ 

[1] NHLBI, Biochem & Biophys Ctr, NIH, Bethesda, MD 20892 USA

[2] NIH, Off Intramural Res, Ctr Informat Technol, Bethesda, MD 20892 USA

[3] NHLBI, Cell Biol & Physiol Ctr, NIH, Bethesda, MD 20892 USA

[4] NIH, Natl Lib Med, Bethesda, MD 20892 USA

[5] NHLBI, NIH, Bldg 50,Room 2316, Bethesda, MD 20892 USA

关键词: NMR;    paramagnetic relaxation enhancement (PRE);    encounter complex;    nitrogen phosphotransferase system (PTSNtr);    Enzyme I;   

DOI  :  10.1016/j.jmb.2019.04.040

来源: Elsevier

【 摘 要 】

There are two paralogous Escherichia coli phosphotransferase systems, one for sugar import (PTSsugar) and one for nitrogen regulation (PTSNtr), that utilize proteins enzyme I-sugar (EIsugar) and HPr, and enzyme I-Ntr (EINtr) and NPr, respectively. The enzyme I proteins have similar folds, as do their substrates HPr and NPr, yet they show strict specificity for their cognate partner both in stereospecific protein-protein complex formation and in reversible phosphotransfer. Here, we investigate the mechanism of specific EINtr:NPr complex formation by the study of transient encounter complexes. NMR paramagnetic relaxation enhancement experiments demonstrated transient encounter complexes of EINtr not only with the expected partner, NPr, but also with the unexpected partner, HPr. HPr occupies transient sites on EINtr but is unable to complete stereospecific complex formation. By occupying the non-productive transient sites, HPr promotes NPr transient interaction to productive sites closer to the stereospecific binding site and actually enhances specific complex formation between NPr and EINtr. The cellular level of HPr is approximately 150 times higher than that of NPr. Thus, our finding suggests a potential mechanism for cross-regulation of enzyme activity through formation of competitive encounter complexes. Published by Elsevier Ltd.

【 授权许可】

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