Structural and functional characterization of the bacterial biofilm activator RemA

Tamara Hoffmann,Christopher-Nils Mais,Daniel B Kearns,Fabiana Burchert,Patricia Bedrunka,Devid Mrusek,Erhard Bremer,Florian Altegoer,Gert Bange

doi:10.1038/s41467-021-26005-4

Abstract

Bacillus subtilis can form structurally complex biofilms on solid or liquid surfaces, which requires expression of genes for matrix production. The transcription of these genes is activated by regulatory protein RemA, which binds to poorly conserved, repetitive DNA regions but lacks obvious DNA-binding motifs or domains. Here, we present the structure of the RemA homologue from Geobacillus thermodenitrificans, showing a unique octameric ring with the potential to form a 16-meric superstructure. These results, together with further biochemical and in vivo characterization of B. subtilis RemA, suggests that the protein can wrap DNA around its ring-like structure through a LytTR-related domain.

Highlights

Bacillus subtilis can form structurally complex biofilms on solid or liquid surfaces, which requires expression of genes for matrix production
The (Gt)residues impacts the structure of (RemA) protein containing an N-terminal Histag was purified by a two-stepped protocol consisting of a Ni-ion affinity followed by a size exclusion chromatography (SEC) step
Multi-angle light scattering analysis (MALS) of the two major SEC peaks of (Gt)RemA (MW = 9.6 kDa; 87 amino acids) indicated two particles with the approximate molecular weights of 135 kDa ± 15% and 77 kDa ± 10%, which might correspond to 16-mers (RemA)[16] and 8-mers (RemA)[8] of the protein, respectively (Fig. 1b). The ratio of both peaks was dependent on the protein concentration, indicating that higher concentrations promote the formation of (RemA)[16] (Supplementary Figs. 1a, b). These findings suggest that RemA can form 8- and 16-mers in a concentration-dependent manner

Summary

Introduction

Bacillus subtilis can form structurally complex biofilms on solid or liquid surfaces, which requires expression of genes for matrix production. Resulting from the sequestration of the SinR protein by SinI into a protein complex unable to bind DNA, transcription of operons involved in matrix production (epsA-O), synthesis of the amyloid-like protein TasA (tapA-sipW-tasA), and the gene for the BslA hydrophobin are de-repressed, thereby fostering biofilm formation[6]. In this process, an epigenetic switch couples biofilm formation with inhibition of motility through SlrR, another antagonist of SinR, where the

Methods

Results

Conclusion