Sandbox Reserved 344: Difference between revisions
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=====Un-activated form===== | =====Un-activated form===== | ||
:Under normal physiological conditions, unactivated PhoP occurs mainly as a monomer. At higher concentration unactivated PhoP has been shown to dimerize and act in a similar way to activated and dimerized PhoP. Many regulatory domains isolated from members of the OmpR/PhoB family and in their inactive form, crystalize in a form similar to their activated dimers. | :Under normal physiological conditions, unactivated PhoP occurs mainly as a monomer. At higher concentration unactivated PhoP has been shown to dimerize and act in a similar way to activated and dimerized PhoP. Many regulatory domains isolated from members of the OmpR/PhoB family and in their inactive form, crystalize in a form similar to their activated dimers. | ||
=====Activated form===== | =====Activated form===== | ||
:Phosphorylation of the regulatory domain stabilizes dimer formation. | :Phosphorylation of the regulatory domain stabilizes dimer formation. | ||
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:F3 to Lys 101 (salt bridge) | :F3 to Lys 101 (salt bridge) | ||
===Effector domain=== | ===Effector domain=== | ||
The effector domain is activated when PhoP is in dimer form. There is no direct change in conformation conferred on the effector domain by the regulatory domain. The PhoP has a winged helix-turn-helix motif characteristic of the OmpR/PhoB family of response regulators. This winged helix-turn-helix allows binding to DNA and regulation of transcription. Binding occurs at promoters with two repeats of the sequence (T/G)GTTTA, known as the PhoP box.<ref name = "Groisman"/> | The effector domain is activated when PhoP is in dimer form. There is no direct change in conformation conferred on the effector domain by the regulatory domain. The PhoP has a winged helix-turn-helix motif characteristic of the OmpR/PhoB family of response regulators.<ref name = "Hickey"> PMID:20606293</ref> This winged helix-turn-helix allows binding to DNA and regulation of transcription. Binding occurs at promoters with two repeats of the sequence (T/G)GTTTA, known as the PhoP box.<ref name = "Groisman"/> | ||
=Function= | =Function= | ||
Two component systems allow bacteria to respond to changes in their environment. These systems are found mainly in prokaryotes and a few eukaryotes.<ref name = "Mack"> PMID:19371748</ref> The PhoP/PhoQ system, found specifically in gram-negative bacteria, react mainly to a drop in extracellular Mg<sup>2+</sup>. Since the magnesium concentration is typically lower inside the host cell compared to outside, this acts as a trigger to become virulent. Other functions activated by the PhoP/PhoQ system includes adaptation to low Mg<sup>2+</sup> conditions, changes in cell wall, expression of proteases to protect against antimicrobial peptides and various other species specific responses. PhoP in ''Salmonella enterica'' regulates up to 40 proteins.<ref name = "Groisman"/> | Two component systems allow bacteria to respond to changes in their environment. These systems are found mainly in prokaryotes and a few eukaryotes.<ref name = "Mack"> PMID:19371748</ref> The PhoP/PhoQ system, found specifically in gram-negative bacteria, react mainly to a drop in extracellular Mg<sup>2+</sup>. Since the magnesium concentration is typically lower inside the host cell compared to outside, this acts as a trigger to become virulent. Other functions activated by the PhoP/PhoQ system includes adaptation to low Mg<sup>2+</sup> conditions, changes in cell wall, expression of proteases to protect against antimicrobial peptides and various other species specific responses. PhoP in ''Salmonella enterica'' regulates up to 40 proteins.<ref name = "Groisman"/> | ||