FurC (PerR) contributes to the regulation of peptidoglycan remodeling and intercellular molecular transfer in the cyanobacterium Anabaena sp. strain PCC 7120
Cristina Sarasa-Buisan,1,2 Mercedes Nieves-Morión,2 Sergio Arévalo,2 Richard F. Helm,3 Emma Sevilla,1 Ignacio Luque,2 María F. Fillat1
1 Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias e Instituto de Biocomputación y Física de Sistemas Complejos. Universidad de Zaragoza, Zaragoza, Spain
2 Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Sevilla, Spain
3 Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
Microbial extracellular proteins and metabolites provide valuable information concerning how microbes adapt to changing environments. In cyanobacteria, dynamic acclimation strategies involve a variety of regulatory mechanisms, being ferric uptake regulator proteins as key players in this process. In the nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120, FurC (PerR) is a global regulator that modulates the peroxide response and several genes involved in photosynthesis and nitrogen metabolism. To investigate the possible role of FurC in shaping the extracellular environment of Anabaena, the analysis of the extracellular metabolites and proteins of a furC-overexpressing variant was compared to that of the wild-type strain. There were 96 differentially abundant proteins, 78 of which were found for the first time in the extracellular fraction of Anabaena. While these proteins belong to different functional categories, most of them are predicted to be secreted or have a peripheral location. Several stress-related proteins, including PrxA, flavodoxin, and the Dps homolog All1173, accumulated in the exoproteome of furC-overexpressing cells, while decreased levels of FurA and a subset of membrane proteins, including several export proteins and amiC gene products, responsible for nanopore formation, were detected. Direct repression by FurC of some of those genes, including amiC1 and amiC2, could account for odd septal nanopore formation and impaired intercellular molecular transfer observed in the furC-overexpressing variant. Assessment of the exometabolome from both strains revealed the release of two peptidoglycan fragments in furC-overexpressing cells, namely 1,6-anhydro-N-acetyl-β-D-muramic acid (anhydroMurNAc) and its associated disaccharide (β-D-GlcNAc-(1-4)-anhydroMurNAc), suggesting alterations in peptidoglycan breakdown and recycling.
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File Name | File Description | File Type | File Size | File URL |
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Figure S1 (mBio03231-23-s0001.pdf) | MS/MS fragmentation data for anhydroMurNAc and GlcNAc-anhydroMurNAc. | 301.15 KB | Login to download | |
Figure S2 (mBio03231-23-s0002.pdf) | Assessment of the outer membrane integrity in EB2770FurC cells vs the NmR-control strain. | 161.04 KB | Login to download | |
Figure S3 (mBio03231-23-s0003.pdf) | Total images of nanopores in septal peptidoglycan disks of Anabaena WT. | 267.68 KB | Login to download | |
Figure S4 (mBio03231-23-s0004.pdf) | Total images of nanopore arrays in septal peptidoglycan disks of EB2770FurC | 249.03 KB | Login to download | |
Additional experimental details (mBio03231-23-s0005.docx) | Supplemental methods for exoproteome analysis. | docx | 15.59 KB | Login to download |
Table S1 (mBio03231-23-s0006.docx) | .Oligonucleotides used in this study | docx | 18.62 KB | Login to download |
Table S2 (mBio03231-23-s0007.xlsx) | Differentially abundant proteins detected by SWATH-MS in the exoproteome fraction of EB2770FurC compared to that of Anabaena sp. PCC7120. | xlsx | 38.1 KB | Login to download |