Abstract:PDB Reference: archaeal chitinase, 2dsk, r2dsksf.The crystal structure of the catalytic domain of a chitinase from the hyperthermophilic archaeon Pyrococcus furiosus (AD2 PF-ChiA ) has been determined at 1.5 Å resolution. This is the first structure of the catalytic domain of an archaeal chitinase. The overall structure of AD2 PF-ChiA is a TIM-barrel fold with a tunnel-like active site that is a common feature of family 18 chitinases. Although the catalytic residues (Asp522, Asp524 and Glu526) are conserved, c… Show more
“…From the structure-based alignment and phylogenetic information (Figure 5C) we can conclude that the B. rhizoxinica chitinase (Chi) belongs to the family 18 chitinases in subfamily B. The closest structural homolog is PF-ChiA from Pyrococcus furiosus that has endochitinase activity (Nakamura et al, 2007). 10.7554/eLife.03007.008Figure 5.Functional analyses of chitinolytic enzymes.( A ) Chitinase activity in cell-free culture supernatants of an E. coli harboring recombinant chitinase from B. rhizoxinica after incubation for 30, 60, and 90 min, in comparison to the activity of a recombinant S. lividans enzyme.…”
The rice seedling blight fungus Rhizopus microsporus and its endosymbiont Burkholderia rhizoxinica form an unusual, highly specific alliance to produce the highly potent antimitotic phytotoxin rhizoxin. Yet, it has remained a riddle how bacteria invade the fungal cells. Genome mining for potential symbiosis factors and functional analyses revealed that a type 2 secretion system (T2SS) of the bacterial endosymbiont is required for the formation of the endosymbiosis. Comparative proteome analyses show that the T2SS releases chitinolytic enzymes (chitinase, chitosanase) and chitin-binding proteins. The genes responsible for chitinolytic proteins and T2SS components are highly expressed during infection. Through targeted gene knock-outs, sporulation assays and microscopic investigations we found that chitinase is essential for bacteria to enter hyphae. Unprecedented snapshots of the traceless bacterial intrusion were obtained using cryo-electron microscopy. Beyond unveiling the pivotal role of chitinolytic enzymes in the active invasion of a fungus by bacteria, these findings grant unprecedented insight into the fungal cell wall penetration and symbiosis formation.DOI:
http://dx.doi.org/10.7554/eLife.03007.001
“…From the structure-based alignment and phylogenetic information (Figure 5C) we can conclude that the B. rhizoxinica chitinase (Chi) belongs to the family 18 chitinases in subfamily B. The closest structural homolog is PF-ChiA from Pyrococcus furiosus that has endochitinase activity (Nakamura et al, 2007). 10.7554/eLife.03007.008Figure 5.Functional analyses of chitinolytic enzymes.( A ) Chitinase activity in cell-free culture supernatants of an E. coli harboring recombinant chitinase from B. rhizoxinica after incubation for 30, 60, and 90 min, in comparison to the activity of a recombinant S. lividans enzyme.…”
The rice seedling blight fungus Rhizopus microsporus and its endosymbiont Burkholderia rhizoxinica form an unusual, highly specific alliance to produce the highly potent antimitotic phytotoxin rhizoxin. Yet, it has remained a riddle how bacteria invade the fungal cells. Genome mining for potential symbiosis factors and functional analyses revealed that a type 2 secretion system (T2SS) of the bacterial endosymbiont is required for the formation of the endosymbiosis. Comparative proteome analyses show that the T2SS releases chitinolytic enzymes (chitinase, chitosanase) and chitin-binding proteins. The genes responsible for chitinolytic proteins and T2SS components are highly expressed during infection. Through targeted gene knock-outs, sporulation assays and microscopic investigations we found that chitinase is essential for bacteria to enter hyphae. Unprecedented snapshots of the traceless bacterial intrusion were obtained using cryo-electron microscopy. Beyond unveiling the pivotal role of chitinolytic enzymes in the active invasion of a fungus by bacteria, these findings grant unprecedented insight into the fungal cell wall penetration and symbiosis formation.DOI:
http://dx.doi.org/10.7554/eLife.03007.001
“…Published structures on (putatively) endo-acting and (putatively) nonprocessive family 18 chitinases are limited to those of the hevamine (53) and two bacterial enzymes (49,56). However, for these enzymes, structural data are not accompanied by detailed insight in the actual mode of action of the enzymes.…”
Section: Discussionmentioning
confidence: 99%
“…However, for these enzymes, structural data are not accompanied by detailed insight in the actual mode of action of the enzymes. Nakamura et al (56) only describe a structure of a bacterial enzyme, whereas Hsieh et al (49) provide a more detailed FIGURE 4. MD simulations of two processive chitinases, ChiA and ChiB, and two nonprocessive chitinases, ChiC2 and 3IAN.…”
Background: Nature employs processive and nonprocessive glycoside hydrolases to degrade polysaccharides. Results: We solved the Serratia marcescens nonprocessive chitinase (ChiC2) structure and used simulation to identify dynamic hallmarks of processivity in S. marcescens chitinases. Conclusion: Dynamic metrics complement structural insights in determining processivity. Significance: Identification of hallmarks of processivity is a key step toward development of a general, molecular-level theory of glycoside hydrolase processivity.
“…Thus, we focused on the structure and catalytic mechanism of the C-terminal region, the pair of ChBD2 and AD2 of Pf-ChiA. Although the whole structure of Pf-ChiA has not been elucidated, the structure of AD2 has been reported, 5,6 while the structure of ChBD2 is described in this article. ChBD2 (Thr258-Ile358; the residue numbering is in accordance to the PF1233 amino acid sequence) belongs to the carbohydrate-binding module 2 (CBM2) family, as archived in the CAZy ‡ database.…”
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