The Extracytoplasmic Function Sigma Factor–mediated Response to Heavy Metal Stress in
            <i>Caulobacter Crescentus</i>

Lourenço, Rogério F.; Gomes, Suely L.

doi:10.1002/9781119004813.ch114

Cited by 1 publication

(1 citation statement)

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“…While the molecular networks that control cell cycle progression in C. crescentus have been well studied (Curtis and Brun, ) less is known about the signal transduction pathways that enable a sense and respond functionality in the diverse environments that C. crescentus inhabits. Well‐characterized sensory regulatory pathways in C. crescentus include the general stress response, which is governed by a extracytoplasmic family sigma factor σ T , an antisigma factor and the PhyK‐PhyR and LovK‐LovR TCS that coordinately control σ T activity (Foreman et al ., ; Lourenço and Gomes, ), the PhoBR TCS, which mediates the response to phosphate limitation (Lubin et al ., ) and the oxygen sensory pathway FixLJ‐FixK‐FixT, which enables growth under hypoxic conditions (Crosson et al ., ). Recently, the UzcRS TCS, comprised of the HK UzcS and the RR UzcR, was identified as an activator of ~40 operons (Park et al ., ).…”

Section: Introductionmentioning

confidence: 99%

The UzcRS two‐component system in Caulobacter crescentus integrates regulatory input from diverse auxiliary regulators

Park

Overton

Jiao

2019

Molecular Microbiology

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Summary The UzcRS two‐component system in Caulobacter crescentus mediates widespread transcriptional activation in response to the metals U, Zn and Cu. Unexpectedly, a screen for mutations that affected the activity of the UzcR‐regulated urcA promoter (PurcA) revealed four previously uncharacterized proteins whose inactivation led to metal‐independent induction of PurcA. Using molecular genetics and functional genomics, we find that these auxiliary regulators control PurcA expression by modulating the activity of UzcRS through distinct mechanisms. An ABC transporter with a periplasmic metallo‐aminopeptidase domain forms a sensory complex with UzcRS, antagonizing metal dependent stimulation by virtue of its ATPase and peptidase domains. Two MarR‐like transcription factors synergistically regulate UzcRS activity by repressing the expression of the membrane proteins UzcY and UzcZ, which stimulate UzcRS activity and enhance its sensitivity to a more environmentally relevant U/Zn/Cu concentration range. Additionally, the membrane protein UzcX, whose expression is positively regulated by UzcR, provides a mechanism of feedback inhibition within the UzcRS circuit. Collectively, these data suggest that UzcRS functions as the core‐signaling unit within a multicomponent signal transduction pathway that includes a diverse set of auxiliary regulators, providing further insight into the complexity of signaling networks.

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