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Functional and structural properties of a novel cellulosome-like multienzyme complex: efficient glycoside hydrolysis of water-insoluble 7-xylosyl-10-deacetylpaclitaxel.

Dou TY, Luan HW, Ge GB, Dong MM, Zou HF, He YQ, Cui P, Wang JY, Hao DC, Yang SL, Yang L - Sci Rep (2015)

Bottom Line: This cellulosome-like multienzyme complex has a novel structure distinct from the well-documented ones.The key catalytic subunit responsible for the β-xylosidase activity against 10-DAXP is identified to be a novel protein, indicating a new glycoside hydrolase (GH) family.The pioneering work described here offers a novel nanoscale biocatalyst for the production of biofuels and chemicals from renewable plant-based natural resources.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.

ABSTRACT
Cellulosome is a kind of multienzyme complex that displays high activity, selectivity, and stability. Here, we report a novel, non-cellulolytic, cellulosome-like multienzyme complex that produced by the Cellulosimicrobium cellulans wild-type strain F16 isolated from soil microflora. This multienzyme complex, with excellent catalytic efficiency of kcat 13.2 s(-1) to remove the C-7 xylosyl group from 7-xylosyl-10-deacetylpaclitaxel (10-DAXP), has an outstanding tolerance against organic solvents and an excellent general stability, with the long half-life of 214 hours. This cellulosome-like multienzyme complex has a novel structure distinct from the well-documented ones. The key catalytic subunit responsible for the β-xylosidase activity against 10-DAXP is identified to be a novel protein, indicating a new glycoside hydrolase (GH) family. The pioneering work described here offers a novel nanoscale biocatalyst for the production of biofuels and chemicals from renewable plant-based natural resources.

No MeSH data available.


Related in: MedlinePlus

Illustrations Showing Possible Structure-Function Relationships of the Novel Biocatalyst Xyl_I.(a) Illustrations showing presumed structural features that typical xylosidases unable to remove the C-7 xylosyl group from 10-DAXP; (b) presumed structural features that xylosidases like Xyl_S, or LXYL-P-1 capable of removing the C-7 xylosyl group from 10-DAXP; (c) presumed structural features of the stability and the nanoscale multienzyme properties of the cellulosome-like biocatalyst Xyl_I.
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f7: Illustrations Showing Possible Structure-Function Relationships of the Novel Biocatalyst Xyl_I.(a) Illustrations showing presumed structural features that typical xylosidases unable to remove the C-7 xylosyl group from 10-DAXP; (b) presumed structural features that xylosidases like Xyl_S, or LXYL-P-1 capable of removing the C-7 xylosyl group from 10-DAXP; (c) presumed structural features of the stability and the nanoscale multienzyme properties of the cellulosome-like biocatalyst Xyl_I.

Mentions: Previous studies have shown that ordinary β-xylosidases did not show any activity toward 10-DAXP15. The critical reason might be the intrinsic features of the molecular structure of 10-DAXP, i.e., a much larger and hydrophobic aglycone group on the other side of the glycosidic bond. Furthermore, exoglycosidases, including β-glucosidase, β-xylosidase, and β-galactosidase, generally have ‘pocket’ or ‘crater’ topology23. Thus, for ordinary β-xylosidases, the steric hindrance of the aglycone group might block the C-7 β-xylosidic bond of 10-DAXP from reaching the catalytic site inside the ‘pocket’, ultimately preventing it from being hydrolyzed (Fig. 7a). Therefore, β-xylosidases that could remove the C-7 xylosyl group from 10-DAXP should have a novel catalytic center, such as a broader or more flexible ‘pocket’ or ‘crater’ (Fig. 7b). The enzymes that were identified by Cheng et al.22, namely LXYL-P-1 and LXYL-P-2, seem to support this inference. These two enzymes showed a novel primary sequence, and were classified with a considerably low amino acid sequence similarity into the GH family 3, a group of enzymes that in many cases have dual or broad substrate specificities2425. They were also found to have bifunctional β-xylosidase/β-glucosidase activity, which indicates a broader or more flexible catalytic center. Interestingly, the key subunit of the biocatalyst Xyl_I, the hypothetical protein M768_06655, was also novel, which does not belong to any known GH families, and shows a very low sequence identity (<10%) to that of LXYL-P-1 and −2. Although five protein domains of M768_06655 were identified by Pfam, it is eclusive which one is the catalytic center responsible for the β-xylosidase activity against 10-DAXP. However, similar to LXYL-P-1 and −2, the hypothetical protein M768_06655 showed bifunctional β-xylosidase/β-glucosidase activity which, to some extent, supports the above hypothesis. It seems that there are intricate correlations between 10-DAXP β-xylosidase activity and bifunctional β-xylosidase/β-glucosidase activity. As discussed above, these bifunctional enzymes may have a broader or more flexible catalytic center to accommodate the aglycone of 10-DAXP, so that its C-7 β-xylosidic bond could reach the catalytic site and then be hydrolyzed (Fig. 7b).


Functional and structural properties of a novel cellulosome-like multienzyme complex: efficient glycoside hydrolysis of water-insoluble 7-xylosyl-10-deacetylpaclitaxel.

Dou TY, Luan HW, Ge GB, Dong MM, Zou HF, He YQ, Cui P, Wang JY, Hao DC, Yang SL, Yang L - Sci Rep (2015)

Illustrations Showing Possible Structure-Function Relationships of the Novel Biocatalyst Xyl_I.(a) Illustrations showing presumed structural features that typical xylosidases unable to remove the C-7 xylosyl group from 10-DAXP; (b) presumed structural features that xylosidases like Xyl_S, or LXYL-P-1 capable of removing the C-7 xylosyl group from 10-DAXP; (c) presumed structural features of the stability and the nanoscale multienzyme properties of the cellulosome-like biocatalyst Xyl_I.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562250&req=5

f7: Illustrations Showing Possible Structure-Function Relationships of the Novel Biocatalyst Xyl_I.(a) Illustrations showing presumed structural features that typical xylosidases unable to remove the C-7 xylosyl group from 10-DAXP; (b) presumed structural features that xylosidases like Xyl_S, or LXYL-P-1 capable of removing the C-7 xylosyl group from 10-DAXP; (c) presumed structural features of the stability and the nanoscale multienzyme properties of the cellulosome-like biocatalyst Xyl_I.
Mentions: Previous studies have shown that ordinary β-xylosidases did not show any activity toward 10-DAXP15. The critical reason might be the intrinsic features of the molecular structure of 10-DAXP, i.e., a much larger and hydrophobic aglycone group on the other side of the glycosidic bond. Furthermore, exoglycosidases, including β-glucosidase, β-xylosidase, and β-galactosidase, generally have ‘pocket’ or ‘crater’ topology23. Thus, for ordinary β-xylosidases, the steric hindrance of the aglycone group might block the C-7 β-xylosidic bond of 10-DAXP from reaching the catalytic site inside the ‘pocket’, ultimately preventing it from being hydrolyzed (Fig. 7a). Therefore, β-xylosidases that could remove the C-7 xylosyl group from 10-DAXP should have a novel catalytic center, such as a broader or more flexible ‘pocket’ or ‘crater’ (Fig. 7b). The enzymes that were identified by Cheng et al.22, namely LXYL-P-1 and LXYL-P-2, seem to support this inference. These two enzymes showed a novel primary sequence, and were classified with a considerably low amino acid sequence similarity into the GH family 3, a group of enzymes that in many cases have dual or broad substrate specificities2425. They were also found to have bifunctional β-xylosidase/β-glucosidase activity, which indicates a broader or more flexible catalytic center. Interestingly, the key subunit of the biocatalyst Xyl_I, the hypothetical protein M768_06655, was also novel, which does not belong to any known GH families, and shows a very low sequence identity (<10%) to that of LXYL-P-1 and −2. Although five protein domains of M768_06655 were identified by Pfam, it is eclusive which one is the catalytic center responsible for the β-xylosidase activity against 10-DAXP. However, similar to LXYL-P-1 and −2, the hypothetical protein M768_06655 showed bifunctional β-xylosidase/β-glucosidase activity which, to some extent, supports the above hypothesis. It seems that there are intricate correlations between 10-DAXP β-xylosidase activity and bifunctional β-xylosidase/β-glucosidase activity. As discussed above, these bifunctional enzymes may have a broader or more flexible catalytic center to accommodate the aglycone of 10-DAXP, so that its C-7 β-xylosidic bond could reach the catalytic site and then be hydrolyzed (Fig. 7b).

Bottom Line: This cellulosome-like multienzyme complex has a novel structure distinct from the well-documented ones.The key catalytic subunit responsible for the β-xylosidase activity against 10-DAXP is identified to be a novel protein, indicating a new glycoside hydrolase (GH) family.The pioneering work described here offers a novel nanoscale biocatalyst for the production of biofuels and chemicals from renewable plant-based natural resources.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.

ABSTRACT
Cellulosome is a kind of multienzyme complex that displays high activity, selectivity, and stability. Here, we report a novel, non-cellulolytic, cellulosome-like multienzyme complex that produced by the Cellulosimicrobium cellulans wild-type strain F16 isolated from soil microflora. This multienzyme complex, with excellent catalytic efficiency of kcat 13.2 s(-1) to remove the C-7 xylosyl group from 7-xylosyl-10-deacetylpaclitaxel (10-DAXP), has an outstanding tolerance against organic solvents and an excellent general stability, with the long half-life of 214 hours. This cellulosome-like multienzyme complex has a novel structure distinct from the well-documented ones. The key catalytic subunit responsible for the β-xylosidase activity against 10-DAXP is identified to be a novel protein, indicating a new glycoside hydrolase (GH) family. The pioneering work described here offers a novel nanoscale biocatalyst for the production of biofuels and chemicals from renewable plant-based natural resources.

No MeSH data available.


Related in: MedlinePlus