From metagenomic gene discovery to enzymatic breakdown of crosslinks in agricultural fibers for functional products

Authors: Wong, Dominic; Chan, Victor; MARAKAMI, MARIO - Brazilian Biosciences National Laboratory (LNBIO)

Submitted to: Pacifichem Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2015
Publication Date: 5/15/2015
Citation: Wong, D., Chan, V.J., Marakami, M. 2015. From metagenomic gene discovery to enzymatic breakdown of crosslinks in agricultural fibers for functional products. Pacifichem Symposium. Meeting Abstract, BIOL 343.

Interpretive Summary:

Technical Abstract: From the rumen microflora, more than twenty novel genes involved in the hydrolysis of glucuronoarabinoxylans have been discovered and isolated. The specific genes functioning in the breakdown of crosslinkages have been cloned and expressed in E. coli, and the active enzymes purified and extensively characterized. Study of the rumen metagenome produced two novel arabinanases. The endo-acting ARN2 was capable of efficiently degrading branched arabinans, resulting from a large catalytic interface of the protein molecule with high accessibility to substrate binding. The exo-acting ARN3 hydrolyzed debranched arabinan entirely to arabinose, due to the steric impediments at the aglycone-binding of the reducing end of the substrate. Biochemical studies of two novel xyloglucanases, XEG5A and XEG5B, were characterized with endo- and exo-actions, respectively, on natural xyloglucans. The mode of action was related to subtle modification of the -1 subsite topology of the protein structure. The rumen FAE enzymes were shown to catalyze substantial release of ferulate and diferulate from insoluble natural cell wall biopolymers. These three families of enzymes, together with the other enzymes in our inventory, could be used individually and in combination to generate designer oligosaccharides with target functions and bioactivities.