GH115 α-glucuronidase and GH11 xylanase from Paenibacillus sp. JDR-2: potential roles in processing glucuronoxylans

Mun Su Rhee; Neha Sawhney; Young Sik Kim; Hyun Jee Rhee; Jason C Hurlbert; Franz J St John; Guang Nong; John D Rice; James F Preston

doi:10.1007/s00253-016-7899-4

GH115 α-glucuronidase and GH11 xylanase from Paenibacillus sp. JDR-2: potential roles in processing glucuronoxylans

Appl Microbiol Biotechnol. 2017 Feb;101(4):1465-1476. doi: 10.1007/s00253-016-7899-4. Epub 2016 Oct 21.

Authors

Mun Su Rhee^{1

2}, Neha Sawhney^{1

3}, Young Sik Kim¹, Hyun Jee Rhee^{1

4}, Jason C Hurlbert⁵, Franz J St John⁶, Guang Nong¹, John D Rice¹, James F Preston⁷

Affiliations

¹ Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA.
² Xycrobe Therapeutics Inc., 3210 Merryfield Row, San Diego,, CA, 92121,, USA.
³ Department of Chemistry, Vanderbilt University, Nashville, TN, 37235,, USA.
⁴ Department of Materials Science and Engineering, Massachusetts Institute of Technology, 6-113, Cambridge, MA, 02139,, USA.
⁵ Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, SC, 29733, USA.
⁶ Forest Products Laboratory, United States Forest Service, The United States Department of Agriculture, Madison, Madison,, WI, 53726, USA.
⁷ Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA. jpreston@ufl.edu.

PMID: 27766358
DOI: 10.1007/s00253-016-7899-4

Abstract

Paenibacillus sp. JDR-2 (Pjdr2) has been studied as a model for development of bacterial biocatalysts for efficient processing of xylans, methylglucuronoxylan, and methylglucuronoarabinoxylan, the predominant hemicellulosic polysaccharides found in dicots and monocots, respectively. Pjdr2 produces a cell-associated GH10 endoxylanase (Xyn10A₁) that catalyzes depolymerization of xylans to xylobiose, xylotriose, and methylglucuronoxylotriose with methylglucuronate-linked α-1,2 to the nonreducing terminal xylose. A GH10/GH67 xylan utilization regulon includes genes encoding an extracellular cell-associated Xyn10A₁ endoxylanase and an intracellular GH67 α-glucuronidase active on methylglucuronoxylotriose generated by Xyn10A₁ but without activity on methylglucuronoxylotetraose generated by a GH11 endoxylanase. The sequenced genome of Pjdr2 contains three paralogous genes potentially encoding GH115 α-glucuronidases found in certain bacteria and fungi. One of these, Pjdr2_5977, shows enhanced expression during growth on xylans along with Pjdr2_4664 encoding a GH11 endoxylanase. Here, we show that Pjdr2_5977 encodes a GH115 α-glucuronidase, Agu115A, with maximal activity on the aldouronate methylglucuronoxylotetraose selectively generated by a GH11 endoxylanase Xyn11 encoded by Pjdr2_4664. Growth of Pjdr2 on this methylglucuronoxylotetraose supports a process for Xyn11-mediated extracellular depolymerization of methylglucuronoxylan and Agu115A-mediated intracellular deglycosylation as an alternative to the GH10/GH67 system previously defined in this bacterium. A recombinantly expressed enzyme encoded by the Pjdr2 agu115A gene catalyzes removal of 4-O-methylglucuronate residues α-1,2 linked to internal xylose residues in oligoxylosides generated by GH11 and GH30 xylanases and releases methylglucuronate from polymeric methylglucuronoxylan. The GH115 α-glucuronidase from Pjdr2 extends the discovery of this activity to members of the phylum Firmicutes and contributes to a novel system for bioprocessing hemicelluloses.

Keywords: Biofuels and chemicals; GH11 endoxylanase; GH115 α-glucuronidase; Paenibacillus sp. JDR-2; Xylans.

MeSH terms

Endo-1,4-beta Xylanases / metabolism*
Glycoside Hydrolases / metabolism*
Paenibacillus / enzymology*
Paenibacillus / metabolism*
Xylans / metabolism*

Substances

Xylans
glucuronoxylan
Glycoside Hydrolases
alpha-glucuronidase
Endo-1,4-beta Xylanases