Missing link in microbial cellulose decomposition
A University of Tokyo research group has revealed for the first time the three-dimensional structure and mechanism of action of a key enzyme of bio-fuel production, cellobionic acid phosphorylase (CBAP). This result is important basic information for developing the technology to make bio-fuel and other chemical products from biomass.
It has been long thought that hydrolytic enzymes (cellulases) were the main contributors to microbial degradation of cellulose. Recently, the existence of oxidative cellulose-degrading enzymes that dramatically increase the activity efficiency of cellulases have been noted.
When these enzymes degrade cellulose, cellobionic acid is produced. However, it was completely unknown how the cellulolytic microbes further metabolize this compound.
In 2013, one of the members of the research group, Associate Professor Hiroyuki Nakai at the Graduate School of Science and Technology, Niigata University, discovered a new enzyme, cellobionic acid phosphorylase (CBAP).
CBAP catalyzes the degradation of cellobionic acid to produce compounds that are prone to further metabolism and fermentation. Therefore, this enzyme is a missing link between the oxidative cellulose degradation and bioethanol fermentation pathways in microorganisms. However, the three dimensional structure of the enzyme and the mechanism by which it degraded cellobionic acid remained unknown.
In this latest research, the research group lead by Professor Shinya Fushinobu at the University of Tokyo, Graduate School of Agricultural and Life Sciences, used X-ray crystallography to reveal the three-dimensional structure of CBAP isolated from marine bacteria. In addition, the structure of CBAP in complex with cellobionic acid was determined (figure), and the reaction mechanism for decomposing cellobionic acid was revealed.
“This research is extremely interesting from a scientific perspective, but could also contribute to the development of biorefinery technologies that produce biofuels such as ethanol and other useful compounds via biomass degradation by microbes,” says Professor Fushinobu.
Two cellobionic acid phosphorylases molecules pair up to create a dimer. The colored left half and the gray right half are each one enzyme molecule. Cellobionic acid and sulfuric acid ions (a compound similar to phosphoric acid) bound to cellobionic acid phosphorylase are expressed as spheres in the figure.
Young-Woo Nam, Takanori Nihira, Takatoshi Arakawa, Yuka Saito, Motomitsu Kitaoka, Hiroyuki Nakai, and Shinya Fushinobu, "Crystal structure and substrate recognition of cellobionic acid phosphorylase playing a key role in oxidative cellulose degradation by microbes", The Journal of Biological Chemistry Vol. 290, No. 30, pg 18281-18292, doi: 10.1074/jbc.M115.664664.
UTokyo Research article
Euan McKay | ResearchSea
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy