Understanding how bacteria digest plant lignin informs engineering efforts to extract value from lignin.
To determine the structural basis for stereospecificity of bacterial enzymes involved in lignin bond cleavage, researchers solved the crystal structures of the enzymes involved. The detailed structural and biochemical characterization of the lignin degradation pathway members reveals important new aspects of the enzyme mechanisms and determinants of substrate specificity.
Lignin is a combinatorial polymer comprised of monoaromatic units and is a potential source of valuable aromatic chemicals. However, its recalcitrance to chemical or biological digestion presents a major obstacle to the production of second-generation biofuels and other valuable bioproducts. These collaborative studies elucidating mechanisms of lignin degradation may enable the development of efficient pathways for converting lignin into components of advanced biofuels and other bioproducts.
Lignin’srecalcitrance to chemical or biological digestion presents a major obstacle to the production of second-generation biofuels and valuable coproducts from lignin’s monoaromatic units. A catabolic pathway for the enzymatic breakdown of aromatic oligomers linked via β-aryl ether bonds typically found in lignin was reported in the bacterium Sphingobium sp. SYK-6. In a collaborative effort, researchers from the Department of Energy’s (DOE) Great Lakes Bioenergy Research Center (GLBRC) and Joint BioEnergy Institute (JBEI) determined the X-ray crystal structures and biochemical characterizations of several glutathione-dependent β-etherases that participate in the cleavage of lignin. Results from these studies reveal important new aspects of the enzyme mechanisms and the determinants of substrate specificity. As β-aryl ether bonds account for 50 percent to 70 percent of all inter-unit linkages in lignin, understanding the mechanism of enzymatic β-aryl ether cleavage has significant potential for informing ongoing studies on lignin valorization.
N. Kent Peters, SC-2.32, email@example.com, 301-903-5549
George N. Phillips, Jr.
This work was funded by GLBRC and JBEI (DOE Office of Science, Office of Biological and Environmental Research DE-FC02-07ER64494 and DE-AC02-05CH11231, respectively), additional grants from DOE (Office of Science, Office of Basic Energy Sciences, Contract No. DE-AC02-05CH11231 and DE-AC02-06CH11357), grants from the National Institutes of Health (AGM-12006, GM109456, GM098248, P41GM103399, and S10RR027000), the Michigan Economic Development Corporation and the Michigan Technology Tri-Corridor (Grant 085P1000817), National Cancer Institute (ACB-12002), and University of Wisconsin-Madison.
Helmich, K., et al. 2015. “Structural Basis of Stereospecificity in the Bacterial Enzymatic Cleavage of β-aryl Ether Bonds in Lignin,” The Journal of Biological Chemistry, DOI: 10.1074/jbc.M115.694307. (Reference link)
Pereira, J. H., et al. 2016. “Structural and Biochemical Characterization of the Early and Late Enzymes in the Lignin β-aryl Ether Cleavage Pathway from Sphingobium sp SYK-6,” The Journal of Biological Chemistry, DOI: 10.1074/jbc.M115.700427. (Reference link)
SC-23.2 Biological Systems Science Division, BER
BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER
Aug 24, 2019
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]
Aug 08, 2019
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]
Aug 05, 2019
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]
Jul 29, 2019
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]
Jul 15, 2019
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]
List all highlights (possible long download time)