Caprin-1 binding to the critical stress granule protein G3BP1 is influenced by pH
Tim Schulte,
Marc D. Panas,
Xiao Han,
Lucy Williams,
Nancy Kedersha,
Jonas Simon Fleck,
Timothy J. C. Tan,
Xaquin Castro Dopico,
Anders Olsson,
Ainhoa Moliner Morro,
Leo Hanke,
Johan Nilvebrant,
Kim Anh Giang,
Per-Åke Nygren,
Paul Anderson,
Adnane Achour,
Gerald M. McInerney
Affiliations
Tim Schulte
Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, and Division of Infectious Diseases, Karolinska University Hospital, Stockholm, 171 77, Sweden
Marc D. Panas
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
Xiao Han
Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, and Division of Infectious Diseases, Karolinska University Hospital, Stockholm, 171 77, Sweden
Lucy Williams
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
Nancy Kedersha
Division of Rheumatology, Immunity, and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
Jonas Simon Fleck
Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, and Division of Infectious Diseases, Karolinska University Hospital, Stockholm, 171 77, Sweden
Timothy J. C. Tan
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
Xaquin Castro Dopico
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
Anders Olsson
Protein Expression and Characterization, AlbaNova University Center, Royal Institute of Technology, 114 21, Stockholm
Ainhoa Moliner Morro
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
Leo Hanke
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
Johan Nilvebrant
Division of Protein Engineering, Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, AlbaNova University Center, Royal Institute of Technology, 114 21, Stockholm
Kim Anh Giang
Division of Protein Engineering, Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, AlbaNova University Center, Royal Institute of Technology, 114 21, Stockholm
Per-Åke Nygren
Division of Protein Engineering, Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, AlbaNova University Center, Royal Institute of Technology, 114 21, Stockholm
Paul Anderson
Division of Rheumatology, Immunity, and Inflammation, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
Adnane Achour
Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, and Division of Infectious Diseases, Karolinska University Hospital, Stockholm, 171 77, Sweden
Gerald M. McInerney
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
G3BP is the central node within stress-induced protein–RNA interaction networks known as stress granules (SGs). The SG-associated proteins Caprin-1 and USP10 bind mutually exclusively to the NTF2 domain of G3BP1, promoting and inhibiting SG formation, respectively. Herein, we present the crystal structure of G3BP1-NTF2 in complex with a Caprin-1-derived short linear motif (SLiM). Caprin-1 interacts with His-31 and His-62 within a third NTF2-binding site outside those covered by USP10, as confirmed using biochemical and biophysical-binding assays. Nano-differential scanning fluorimetry revealed reduced thermal stability of G3BP1-NTF2 at acidic pH. This destabilization was counterbalanced significantly better by bound USP10 than Caprin-1. The G3BP1/USP10 complex immunoprecipated from human U2OS cells was more resistant to acidic buffer washes than G3BP1/Caprin-1. Acidification of cellular condensates by approximately 0.5 units relative to the cytosol was detected by ratiometric fluorescence analysis of pHluorin2 fused to G3BP1. Cells expressing a Caprin-1/FGDF chimera with higher G3BP1-binding affinity had reduced Caprin-1 levels and slightly reduced condensate sizes. This unexpected finding may suggest that binding of the USP10-derived SLiM to NTF2 reduces the propensity of G3BP1 to enter condensates.