Enzyme Engineering of a D-Ribulose-1-Phosphate 5-Kinase
(2020) KBKM01 20201Pure and Applied Biochemistry
- Abstract
- The world population is continuously growing and will have to be fed. To keep pace with the increasing demand, multiple innovations have been implemented in agriculture during the last decades. The main bottleneck remains the global photosynthetic productivity. The efficiency of photosynthesis is limited, inter alia, by the fixation of CO2 via Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). The poor discrimination of RuBisCO between CO2 and O2 leads to the process of photorespiration, and subsequently to carbon and nitrogen loss. During oxygenic photosynthesis light is converted into energy and used to fix CO2 in the Calvin-Benson cycle via RuBisCO. RuBisCO acts here as a carboxylase, adding CO2 to one molecule of... (More)
- The world population is continuously growing and will have to be fed. To keep pace with the increasing demand, multiple innovations have been implemented in agriculture during the last decades. The main bottleneck remains the global photosynthetic productivity. The efficiency of photosynthesis is limited, inter alia, by the fixation of CO2 via Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). The poor discrimination of RuBisCO between CO2 and O2 leads to the process of photorespiration, and subsequently to carbon and nitrogen loss. During oxygenic photosynthesis light is converted into energy and used to fix CO2 in the Calvin-Benson cycle via RuBisCO. RuBisCO acts here as a carboxylase, adding CO2 to one molecule of ribulose-1,5-bisphosphate and producing two molecules of 3-phosphoglycerate. In photorespiration RuBisCO takes instead of CO2 a molecule of O2 and, acting as an oxygenase, generates 2-phosphoglycolate which is recycled back into the Calvin-Benson Cycle. This recycling process releases CO2 and nitrogen and costs chemical energy. One approach to solve this limitation of carbon fixation is to develop synthetic photorespiration bypass pathways that release no CO2. Several different options of bypasses were proposed in silico (Trudeau et al., 2018) and the overall aim is to follow with a proof of concept in vitro and then to establish an efficient bypass in vivo. The proposed bypasses rely on pre-existing enzymatic activities but also on enzymatic activities that are not known in nature yet. The aim of this project was to engineer a D-ribulose-1-phosphate 5-kinase for the proposed ribulose-1-phosphate shunt (Figure 1) via rational design of the promiscuous activity of a phosphoribulokinase that natively phosphorylates ribulose-5-phosphate. (Less)
- Popular Abstract
- World population is growing but the production of crops is limited due to several factors. One is that cropland is limited and will further decrease due to climate change. Another factor is the limited efficiency of plants. It is commonly known that plants convert CO2 to oxygen via photosynthesis. However, sometimes plants, especially crops, take oxygen instead. When this is the case, the plant accumulates and releases CO2 and other toxic chemicals to the environment and wastes energy. The energy that would otherwise be used to let the plant grow. This process is called photorespiration which is a metabolic pathway composed of several different chemical reactions in the plant´s cells. It is considered as one of the natural bottlenecks of... (More)
- World population is growing but the production of crops is limited due to several factors. One is that cropland is limited and will further decrease due to climate change. Another factor is the limited efficiency of plants. It is commonly known that plants convert CO2 to oxygen via photosynthesis. However, sometimes plants, especially crops, take oxygen instead. When this is the case, the plant accumulates and releases CO2 and other toxic chemicals to the environment and wastes energy. The energy that would otherwise be used to let the plant grow. This process is called photorespiration which is a metabolic pathway composed of several different chemical reactions in the plant´s cells. It is considered as one of the natural bottlenecks of photosynthesis efficiency. Solving this problem of photorespiration would increase the efficiency of plants and could provide food to the growing world population and the millions already malnourished. One proposal is to bypass photorespiration with other chemical reactions utilising different enzymes. The bypass this project is based on needs an enzymatic reaction that is not known in nature yet. The conversion of ribulose 1-phosphate to ribulose 1,5-bisphosphate. There are several enzymes known in nature that form ribulose 1,5-bisphosphate from ribulose 5-phosphate. A number of these enzymes were screened for additional ability to convert ribulose 1-phosphate. This is called “promiscuous activity” since the enzyme has a main function and a less efficient side function. One candidate enzyme was found, and models of its ancestors were done. One ancestor had higher activity and was the starting point for further optimisation via mutations. While the target activity was increased, it is likely not sufficient enough to be implemented into a functioning bypass of photorespiration. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9029616
- author
- Eicholt, Lars LU
- supervisor
- organization
- course
- KBKM01 20201
- year
- 2020
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Photorespiration, Enzyme Engineering, Rational Design, Food Security, Metabolic Engineering, Applied biochemistry, Tillämpad biokemi
- language
- English
- id
- 9029616
- date added to LUP
- 2020-09-25 17:05:35
- date last changed
- 2020-09-25 17:05:35
@misc{9029616,
abstract = {{The world population is continuously growing and will have to be fed. To keep pace with the increasing demand, multiple innovations have been implemented in agriculture during the last decades. The main bottleneck remains the global photosynthetic productivity. The efficiency of photosynthesis is limited, inter alia, by the fixation of CO2 via Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). The poor discrimination of RuBisCO between CO2 and O2 leads to the process of photorespiration, and subsequently to carbon and nitrogen loss. During oxygenic photosynthesis light is converted into energy and used to fix CO2 in the Calvin-Benson cycle via RuBisCO. RuBisCO acts here as a carboxylase, adding CO2 to one molecule of ribulose-1,5-bisphosphate and producing two molecules of 3-phosphoglycerate. In photorespiration RuBisCO takes instead of CO2 a molecule of O2 and, acting as an oxygenase, generates 2-phosphoglycolate which is recycled back into the Calvin-Benson Cycle. This recycling process releases CO2 and nitrogen and costs chemical energy. One approach to solve this limitation of carbon fixation is to develop synthetic photorespiration bypass pathways that release no CO2. Several different options of bypasses were proposed in silico (Trudeau et al., 2018) and the overall aim is to follow with a proof of concept in vitro and then to establish an efficient bypass in vivo. The proposed bypasses rely on pre-existing enzymatic activities but also on enzymatic activities that are not known in nature yet. The aim of this project was to engineer a D-ribulose-1-phosphate 5-kinase for the proposed ribulose-1-phosphate shunt (Figure 1) via rational design of the promiscuous activity of a phosphoribulokinase that natively phosphorylates ribulose-5-phosphate.}},
author = {{Eicholt, Lars}},
language = {{eng}},
note = {{Student Paper}},
title = {{Enzyme Engineering of a D-Ribulose-1-Phosphate 5-Kinase}},
year = {{2020}},
}