رسالة جامعية
Role of Signal Transduction Domains in Histidine Kinase Evolution and Activity
| العنوان: | Role of Signal Transduction Domains in Histidine Kinase Evolution and Activity |
|---|---|
| المؤلفون: | Mensa, Bruk |
| المساهمون: | DeGrado, William F |
| بيانات النشر: | eScholarship, University of California |
| سنة النشر: | 2021 |
| المجموعة: | University of California: eScholarship |
| مصطلحات موضوعية: | Biology, Molecular biology, Biophysics, Allostery, HAMP, Histidine Kinase, Library, modeling, signal transduction |
| الوصف: | The process by which various upstream sensor and signal-transduction domains of bacterial histidine kinases (HKs) modulate the activity of the conserved autokinase domain remains poorly understood. Specifically, why do most HKs contain modularly inserted signal transduction domains? How do HKs robustly evolve and finetune the coupling between stimulus sensor domains and the conserved autokinase domain, which are often separated by 10s of nanometers? What is the role of these intervening domains in fine-tuning signaling parameters such as the minimum/maximum responsiveness, mid-point, and steepness of signal transition of an HK? In this work, we examine signal transduction through model E. coli HKs, PhoQ and CpxA, which contain one of the most abundant signal transduction domains in HKs, the HAMP domain. We first generate a large set of single-point mutants of PhoQ, and simultaneously measure the signaling state of the ligand-binding sensor and the kinase activity of the autokinase in vitro, at several inducing ligand concentrations to assess the coupling between these two domains. We demonstrate that point mutants in the HAMP signal transduction domain significantly modulate the coupled behavior of the sensor and autokinase, producing markedly varied ligand-dependent responses. We further use the insertion of poly-glycine motifs (Gly7) to decouple domains from one another and qualitatively show that, intrinsically, the sensor domain has a drastically poor ligand-dependent state transition propensity, and similarly, the autokinase domain has a drastically high basal kinase activity. The HAMP domain strongly couples to both domains and is sufficient to adjust these propensities to what is observed in the full length PhoQ. We suggest that signal transduction in PhoQ occurs by an allosteric coupling mechanism, in which the HAMP domain strongly couples to and acts in opposition the underlying signaling state equilibria of PhoQ such that it is maximally responsive to physiologically relevant ranges of stimuli. We ... |
| نوع الوثيقة: | thesis |
| وصف الملف: | application/pdf |
| اللغة: | English |
| العلاقة: | qt5nm7534s; https://escholarship.org/uc/item/5nm7534sTest; https://escholarship.org/content/qt5nm7534s/qt5nm7534s.pdfTest |
| الإتاحة: | https://escholarship.org/uc/item/5nm7534sTest https://escholarship.org/content/qt5nm7534s/qt5nm7534s.pdfTest |
| حقوق: | public |
| رقم الانضمام: | edsbas.C7F47B |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |