Pantoea stewartii WceF is a glycan biofilm-modifying enzyme with a bacteriophage tailspike-like fold

Abstract

Pathogenic microorganisms often reside in glycan-based biofilms. Concentration and chain length distribution of these mostly anionic exopolysaccharides (EPS) determine the overall biophysical properties of a biofilm and result in a highly viscous environment. Bacterial communities regulate this biofilm state via intracellular small-molecule signaling to initiate EPS synthesis. Reorganization or degradation of this glycan matrix, however, requires the action of extracellular glycosidases. So far, these were mainly described for bacteriophages that must degrade biofilms for gaining access to host bacteria. The plant pathogen Pantoea stewartii ( P. stewartii ) encodes the protein WceF within its EPS synthesis cluster. WceF has homologs in various biofilm forming plant pathogens of the Erwinia family. In this work, we show that WceF is a glycosidase active on stewartan, the main P. stewartii EPS biofilm component. WceF has remarkable structural similarity with bacteriophage tailspike proteins (TSPs). Crystal structure analysis showed a native trimer of right-handed parallel β-helices. Despite its similar fold, WceF lacks the high stability found in bacteriophage TSPs. WceF is a stewartan hydrolase and produces oligosaccharides, corresponding to single stewartan repeat units. However, compared with a stewartan-specific glycan hydrolase of bacteriophage origin, WceF showed lectin-like autoagglutination with stewartan, resulting in notably slower EPS cleavage velocities. This emphasizes that the bacterial enzyme WceF has a role in P. stewartii biofilm glycan matrix reorganization clearly different from that of a bacteriophage exopolysaccharide depolymerase.

Ice nucleation active bacteria metabolites as antibiofilm agent to control Aeromonas hydrophila and Streptococcus agalactiae infections in Aquaculture

“…In previous studies, it was found that INA bacteria, Pantoea stewartii , is able to secrete WceF, an enzyme which is able to cleaves stewartan exopolysaccharide [ 49 ]. Other studies also found that aqueous extract of Enterobacter sp., inhibits Biofilm of staphylococcal [ 50 ].…”

Insights into the Alcyoneusvirus Adsorption Complex

“…According to AlphaFold2, the 110 N-terminal residues of gp526 form a six-stranded beta sandwich preceded by an α-helix, i.e., a fold similar to that of the head domain D1 of CBA120 TSP1 (4oj6 [30]). The body of gp526 (residues 113-432) comprises two triangular domains (of which one, BD1, is similar to a Knob 2 domain of P. aeruginosa R1 pyocin fiber PALES_06171; 6cl5 [55]) and a large β-sandwich domain, which was a good match to that of a glycan biofilm-modifying enzyme WceF from Pantoea stewartii (6tgf [59]). Another β-sandwich domain is located at the gp526 C-terminus and, according to Dali, its structural homolog is also present in the TSP from Acinetobacter baumanii phage phiAB6 (5jse [60]).…”

Three Phages One Host: Isolation and Characterization of Pantoea agglomerans Phages from a Grasshopper Specimen

“…While a CD search failed to identify any conserved domains that would imply EPS depolymerase activity for either of these three proteins, the top HHpred hit for each of the three of them was to a PDB structure (6TGF_E; probabilities ≥ 99.92, e-values ≤ 4.5 × 10 −24 ), representing a Pantoea stewartii WceF-a glycan biofilm-modifying enzyme with a bacteriophage tailspike-like parallel beta-helix fold. It was recently shown that WceF is a glycosidase active on stewartan, which acts as the main P. stewartii EPS biofilm component, and that WceF is very similar to bacteriophage tailspike proteins [51]. The same authors also noted that WceF homologs are also present in other plant pathogens of bacterial origin, but the functional role of these proteins is so far not fully understood [51].…”

“…It was recently shown that WceF is a glycosidase active on stewartan, which acts as the main P. stewartii EPS biofilm component, and that WceF is very similar to bacteriophage tailspike proteins [51]. The same authors also noted that WceF homologs are also present in other plant pathogens of bacterial origin, but the functional role of these proteins is so far not fully understood [51]. Although ORFs encoding these products overlapped in the genome of Nafs113 by about 30 bp, they were in +1 and +3 reading frames, respectively.…”