Title: Metabolic Sensing of Extracytoplasmic Copper Availability via Translational Control by a Nascent Exported Protein

Abstract

Metabolic sensing is a crucial prerequisite for cells to adjust their physiology to rapidly changing environments. In bacteria, the response to intra- and extracellular ligands is primarily controlled by transcriptional regulators, which activate or repress gene expression to ensure metabolic acclimation. Translational control, such as ribosomal stalling, can also contribute to cellular acclimation and has been shown to mediate responses to changing intracellular molecules. In the current study, we demonstrate that the cotranslational export of the Rhodobacter capsulatus protein CutF regulates the translation of the downstream cutO-encoded multicopper oxidase CutO in response to extracellular copper (Cu). Our data show that CutF, acting as a Cu sensor, is cotranslationally exported by the signal recognition particle pathway. The binding of Cu to the periplasmically exposed Cu-binding motif of CutF delays its cotranslational export via its C-terminal ribosome stalling-like motif. This allows for the unfolding of an mRNA stem-loop sequence that shields the ribosomebinding site of cutO, which favors its subsequent translation. Bioinformatic analyses reveal that CutF-like proteins are widely distributed in bacteria and are often located upstream of genes involved in transition metal homeostasis. Our overall findings illustrate a highly conserved control mechanism using the cotranslational export of a protein acting asmore » a sensor to integrate the changing availability of extracellular nutrients into metabolic acclimation. Metabolite sensing is a fundamental biological process, and the perception of dynamic changes in the extracellular environment is of paramount importance for the survival of organisms. Bacteria usually adjust their metabolisms to changing environments via transcriptional regulation. Here, using Rhodobacter capsulatus, we describe an alternative translational mechanism that controls the bacterial response to the presence of copper, a toxic micronutrient. This mechanism involves a cotranslationally secreted protein that, in the presence of copper, undergoes a process resembling ribosomal stalling. This allows for the unfolding of a downstream mRNA stem-loop and enables the translation of the adjacent Cu-detoxifying multicopper oxidase. Bioinformatic analyses reveal that such proteins are widespread, suggesting that metabolic sensing using ribosome-arrested nascent secreted proteins acting as sensors may be a common strategy for the integration of environmental signals into metabolic adaptations.« less

Authors:

Öztürk, Yavuz ^[1]; Andrei, Andreea ^[2]; Blaby-Haas, Crysten E. ^[3]; Daum, Noel ^[1]; Daldal, Fevzi  ^[4];

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Koch, Hans-Georg ^[1]; Johnson, ed., Michael David Leslie

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1. Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
2. Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany, Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
3. Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, USA, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, USA
4. Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA

Publication Date:

Tue Feb 28 00:00:00 EST 2023

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC), Basic Energy Sciences (BES); Alexander von Humboldt Foundation; German Research Foundation (DFG)

OSTI Identifier:

1907710

Alternate Identifier(s):

OSTI ID: 1972194

Grant/Contract Number:  

SC0018301; FOG-91ER20052; AC02-05CH11231; FG02-91ER20052; KO2184/8; KO2184/9; SFB1381

Resource Type:

Published Article

Journal Name:

mBio (Online)

Additional Journal Information:

Journal Name: mBio (Online) Journal Volume: 14 Journal Issue: 1; Journal ID: ISSN 2150-7511

Publisher:

American Society for Microbiology

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; rhodobacter capsulatus; metabolite sensing; copper homeostasis; translational control; multicopper oxidase