Microorganisms with increased photosynthetic capacity
Inventors
Roberts, James • CARRIERI, Damian • Heinnickel, Mark
Assignees
Lumen Bioscience Inc • Reliance Holding USA Inc
Publication Number
US-10654901-B2
Publication Date
2020-05-19
Expiration Date
2036-04-22
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Abstract
Microorganisms with increased photosynthetic capacity are described. Increased photosynthetic capacity is achieved by down-regulating activity of the RpaB pathway. The microorganisms include Cyanobacteria, including genetically-modified Cyanobacteria.
Core Innovation
The invention provides genetically modified microorganisms, particularly Cyanobacteria, with increased photosynthetic capacity achieved by down-regulating the activity of the RpaB pathway. This is accomplished using genetic modifications such as the introduction of exogenous nucleotide sequences that express specific protein fragments (decoys) or the use of CRISPRi to interfere with pathway signaling components.
Down-regulation of the RpaB pathway leads to enhanced photosynthesis, as measured by increased oxygen evolution and electron transport chain activity. The patent describes mechanisms such as expressing N-terminal fragments of RpaB or SrrA (which act as decoys lacking DNA binding domains), or transcriptional interference targeting pathway kinases, resulting in up-regulation of photosynthetic genes and, consequently, increased biomass accumulation and carbon fixation.
The problem addressed is the limited yield and growth efficiency of photosynthetic microorganisms for applications in energy, fuel, chemical, food production, and environmental carbon dioxide processing. Traditional approaches using crops or unmodified microorganisms have limitations regarding yield per unit area and resource competition with edible crops. By genetically modifying the RpaB pathway, the invention enables higher productivity in microorganisms such as Cyanobacteria, overcoming these limitations.
Claims Coverage
The patent claims cover one main inventive feature based on the independent claim.
Genetically-modified Cyanobacterium expressing an N-terminal fragment of RpaB to down-regulate RpaB pathway activity
A genetically-modified Cyanobacterium comprises an exogenous nucleotide sequence (SEQ ID NO: 23) that encodes and expresses an N-terminal fragment of the RpaB polypeptide (SEQ ID NO: 2). - The N-terminal fragment lacks a DNA binding domain or contains a non-functional DNA binding domain. - This fragment is expressed under the control of a promoter, which may be an inducible promoter or endogenous to the genome of the genetically-modified Cyanobacterium. - Expression of this fragment leads to down-regulation of RpaB pathway activity compared to a Cyanobacterium of the same species without the exogenous nucleotide sequence. - The genetically-modified Cyanobacterium may be selected from Synechococcus elongatus, Arthrospira maxima, Arthrospira platensis, and Cyanobacterium aponinum. - The modified Cyanobacterium exhibits increased photosynthetic capacity and/or increased photosynthetic biomass accumulation from photoautotrophic growth as compared to a non-modified Cyanobacterium of the same species.
In summary, the inventive feature involves genetically engineering Cyanobacteria to express a specific truncated RpaB fragment that modulates RpaB pathway activity, resulting in enhanced photosynthesis and growth.
Stated Advantages
Increased photosynthetic capacity, leading to enhanced electron transport and maximal oxygen evolution in photosynthetic microorganisms.
Increased total carbon fixation, production of carbon containing compounds, and growth (biomass accumulation).
Documented Applications
Cultivation of genetically-modified photosynthetic microorganisms, such as Cyanobacteria, for increased production of energy, fuel, chemicals, and food.
Processing of environmental carbon dioxide using the modified microorganisms.
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