Solution NMR structure of Se0862, a highly conserved cyanobacterial protein involved in biofilm formation

Abstract

Biofilms are accumulations of microorganisms embedded in extracellular matrices that protect against external factors and stressful environments. Cyanobacterial biofilms are ubiquitous and have potential for treatment of wastewater and sustainable production of biofuels. But the underlying mechanisms regulating cyanobacterial biofilm formation are unclear. Here, we report the solution NMR structure of a protein, Se0862, conserved across diverse cyanobacterial species and involved in regulation of biofilm formation in the cyanobacterium Synechococcus elongatus PCC 7942. Se0862 is a class α+β protein with ααββββαα topology and roll architecture, consisting of a fourstranded β-sheet that is flanked by four α-helices on one side. Conserved surface residues constitute a hydrophobic pocket and charged regions that are likely also present in Se0862 orthologs.

A Cyanobacterial Component Required for Pilus Biogenesis Affects the Exoproteome

“…A genetic approach uncovered a highly conserved cyanobacterial protein (EbsA [ e ssential for b iofilm s uppression A ]) that does not exhibit sequence similarity to proteins of known function. Structurally, EbsA belongs to the α+β class and has a roll architecture; however, comparisons with other protein structures did not provide significant insights into its role in biofilm suppression ( 37 ). We revealed a tripartite complex of EbsA, PilB, and the Hfq RNA chaperone.…”

Transcriptomic and phenomic investigations reveal elements in biofilm repression and formation in the cyanobacteriumSynechococcus elongatusPCC 7942

“…1B,C,D & S2, File S3 Sheet 6). While it is reasonable that tsaP, pilD , and the second pilT genes do not have notable impacts on biofilm formation due to degeneracy or their encoded proteins’ roles as accessories to the pilus, the genes of the Hfq-EbsA-PilB tripartite complex 23 or the EbfE-PteB 26 maturation-secretion system play important roles that likely act at post-transcriptional levels 23,55 . These results demonstrate the limitations of using changes in expression level as a proxy for contribution to a particular phenotype.…”

“…Gene categorical information, including known biofilm genes from previous S. elongatus PCC 7942 biofilm publications 22,23,26,27,55 , pili genes described by Taton, et al 24 , essentiality and conservation data from Rubin, et al 32 , functional categories from the JGI IGM 56 and CyanoBase 57 databases, and signal peptide and secretion predictions 58–63 , were amassed for all genes in the S. elongatus PCC 7942 genome from appropriate sources and are provided in Supplemental Tables S1-3. Significant enrichments of genes in each interest group identified for RNA-Seq and RB-TnSeq data comparison sets for each of the informational categories were determined using custom R scripts to perform two-sided Fisher’s exact tests, with FDR-adjusted p-values ≤ 0.05 being designated as significant.…”

Assessment of prediction methods for protein structures determined by NMR in CASP14: impact of AlphaFold2

“…The cyanobacterium Synechococcus elongatus encodes a conserved protein Se0862, CASP14 target T1029, that is required for biofilm regulation. 47 Isotope-enriched samples of Se0862 were produced by N.Z. and A.L.…”

“…In this work, a chemical-shift based CS-Rosetta model was used to guide the NOESY peak assignments, and NOESY peak assignments were restricted to only cross peaks with low assignment ambiguity. The solution structure was determined from 2045 distance restraints, 192 dihedral angle restraints derived from backbone chemical shift data using Talos-N, and 175 RDCs for H N -N, H α -C α , and C α -C 0 bond vectors 47 using Xplor-NIH. 48 The resulting structure is a well-converged α + β structure with ααββββαα topology.…”