Innovating research, policy and education in synthetic and systems biology

SynthSys Seminar - Dr David Lea-Smith on 26 Oct 2017

Understanding and manipulating cyanobacteria, a phylum of environmental and biotechnological importance
David Lea-Smith (University of East Anglia)

Cyanobacteria (oxygenic photosynthetic bacteria) are complicated prokaryotes, incorporating a cell wall similar to other Gram-negative bacteria, internal thylakoid membranes, in which photosynthesis and energy generation occur, and carboxysomes, the site of carbon fixation. Cyanobacteria are also potential platforms for synthetic biology applications, given their ability to convert solar energy efficiently into biomass. However, our understanding of these organisms, especially how proteins are targeted to different compartments, is limited. Using subcellular fractionation and quantitative proteomics we have developed the most extensive subcellular map of the proteome of a cyanobacterial cell, identifying ~67% of Synechocystis sp. PCC 6803 proteins and mapping 1,711 proteins to six specific subcellular regions. Combined with genetic and bioinformatics tools we have developed, this has allowed us to generate optimised strains for industrial applications. For example, we have successfully targeted proteorhodopsin, a green light absorbing, proton pumping protein, to thylakoid membranes. This resulted in a recombinant strain with improved growth and 18% higher biomass accumulation. Another strain, in which five electron sinks were deleted, demonstrates power output of 0.53 W m-2 in biophotovoltaic devices, which uses photosynthetic organisms to convert sunlight into electricity. In this talk I will discuss these tools and developments, and how they can be applied to further develop strains for production of biofuels, industrial chemicals and electricity.

Selected papers from the author.
Lea-Smith DJ*, Ortiz-Suarez ML, Lenn T, Nuernberg DJ, Baers LL, Davey MP, Cotton CAR, Mastroianni M, Bombelli B, Ungerer P, Stevens TJ, Smith AG, Bond PJ, Mullineaux CW, Howe CJ (2016). Hydrocarbons are essential for optimal cell size, division and growth of cyanobacteria. Plant Physiology 172 (3), 1928-1940. *Corresponding author.
Lea-Smith DJ, Bombelli P, Vasudevan AG, Howe CJ (2016). Photosynthetic, respiratory and extracellular electron transport pathways in cyanobacteria. Biochemica Biophysica Acta-Bioenergetics 1857 (3), 247-255.
Lea-Smith DJ*, Biller SJ, Davey MP, Cotton CAR, Perez Sepulveda BM, Turchyn AV, Scanlan DJ, Smith AG, Chisholm SW, Howe CJ (2015). Major contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle. PNAS 112 (44), 13591-13596. *Corresponding author.
Lea-Smith DJ*, Bombelli P, Dennis JS, Scott SA, Smith AG, Howe CJ (2014). Phycobilisome-Deficient Strains of Synechocystis sp. PCC 6803 Have Reduced Size and Require Carbon-Limiting Conditions to Exhibit Enhanced Productivity. Plant physiology 165 (2), 705-714. *Corresponding author.
Lea-Smith DJ, Ross N, Zori M, Bendall DS, Dennis JS, Scott SA, Smith AG, Howe CJ (2013). Thylakoid terminal oxidases are essential for the cyanobacterium Synechocystis sp. PCC 6803 to survive rapidly changing light intensities. Plant physiology 162 (1), 484-49.
Time: 12noon, Thursday 26th October
Venue: Swann Building Seminar room 7.20, Kings Buildings
Host: Alistair McCormick