Potential Regulatory Role of Competitive Encounter Complexes in Paralogous Phosphotransferase Systems.
J Mol Biol
; 431(12): 2331-2342, 2019 05 31.
Article
em En
| MEDLINE
| ID: mdl-31071328
ABSTRACT
There are two paralogous Escherichia coli phosphotransferase systems, one for sugar import (PTSsugar) and one for nitrogen regulation (PTSNtr), that utilize proteins enzyme Isugar (EIsugar) and HPr, and enzyme INtr (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 EINtrNPr 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.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fragmentos de Peptídeos
/
Fosfotransferases
/
Sistema Fosfotransferase de Açúcar do Fosfoenolpiruvato
/
Proteínas de Escherichia coli
/
Proteínas de Ligação a Fosfato
/
Escherichia coli
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
J Mol Biol
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Estados Unidos