Robust Control of PEP Formation Rate in the Carbon Fixation Pathway of C 4 Plants by a Bi-functional Enzyme

Yuval Hart, Avraham E. Mayo, Ron Milo, Uri Alon

פרסום מחקרי: פרסום בכתב עתמאמרביקורת עמיתים

תקציר

Background: C 4 plants such as corn and sugarcane assimilate atmospheric CO 2 into biomass by means of the C 4 carbon fixation pathway. We asked how PEP formation rate, a key step in the carbon fixation pathway, might work at a precise rate, regulated by light, despite fluctuations in substrate and enzyme levels constituting and regulating this process.Results: We present a putative mechanism for robustness in C 4 carbon fixation, involving a key enzyme in the pathway, pyruvate orthophosphate dikinase (PPDK), which is regulated by a bifunctional enzyme, Regulatory Protein (RP). The robust mechanism is based on avidity of the bifunctional enzyme RP to its multimeric substrate PPDK, and on a product-inhibition feedback loop that couples the system output to the activity of the bifunctional regulator. The model provides an explanation for several unusual biochemical characteristics of the system and predicts that the system's output, phosphoenolpyruvate (PEP) formation rate, is insensitive to fluctuations in enzyme levels (PPDK and RP), substrate levels (ATP and pyruvate) and the catalytic rate of PPDK, while remaining sensitive to the system's input (light levels).Conclusions: The presented PPDK mechanism is a new way to achieve robustness using product inhibition as a feedback loop on a bifunctional regulatory enzyme. This mechanism exhibits robustness to protein and metabolite levels as well as to catalytic rate changes. At the same time, the output of the system remains tuned to input levels.

שפה מקוריתאנגלית אמריקאית
מספר המאמר171
מספר עמודים12
כתב עתBMC Systems Biology
כרך5
מזהי עצם דיגיטלי (DOIs)
סטטוס פרסוםפורסם - 24 אוק׳ 2011

ASJC Scopus subject areas

  • ???subjectarea.asjc.1300.1315???
  • ???subjectarea.asjc.2600.2611???
  • ???subjectarea.asjc.1300.1312???
  • ???subjectarea.asjc.1700.1706???
  • ???subjectarea.asjc.2600.2604???

טביעת אצבע

להלן מוצגים תחומי המחקר של הפרסום 'Robust Control of PEP Formation Rate in the Carbon Fixation Pathway of C 4 Plants by a Bi-functional Enzyme'. יחד הם יוצרים טביעת אצבע ייחודית.

פורמט ציטוט ביבליוגרפי