New Publication: Tradeoffs in growth speed and robustness in cyanobacteria

Rui and Michael's paper on CRSIPRi screens in Synechocystis was published in The Plant Cell. We report on essentiality of many genes in this model strain across 11 growth conditions. We also find genes that are expressed "wastefully," in some growth conditions. Thank you to Gilles Peltier and Yonghua Li-Bensson at CEA Cadarache, where Rui spent 3 months on a FEMS fellowship. Michael provides all data in an interactive web application "ShinyLib."

There is also an Editorial summary, "What do photosynthetic organisms need to thrive in all circumstances?"

Miao Plant Cell screenshot CRISPR interference screens reveal growth–robustness tradeoffs in Synechocystis sp. PCC 6803 across growth conditions

Conference: Gordon Research Conference on Photosynthesis in Maine, USA

Paul was an invited speaker at the Gordon Conference on Photosynthesis, at Sunday River Resort, Maine. His talk was in the session, "Manipulation of Photosynthesis for Energy and Products." The talk was

"Chemoproteomics to Identify Metabolite Regulation of Photosynthesis and Carbon Fixation”

Metabolic engineering of microbes to produce compounds of interest often involves dramatic alteration of metabolite pools. An often-overlooked consequence is that accumulating metabolites may negatively affect enzyme activity through competitive or allosteric inhibition. Additionally, post-translational regulation of enzyme activity can complicate metabolic engineering, as pathway flux becomes less sensitive to artificial enzyme overexpression. Here I will describe our application of chemoproteomics methods to identify metabolite-protein interactions in the proteomes of cyanobacteria and chloroplasts. In a first study, we found widespread interaction of tested metabolites with enzymes in central carbon metabolism, but that only a fraction of these interactions affect catalysis. For example, the Calvin cycle intermediate glyceraldehyde phosphate (GAP) stimulated activity of the Calvin cycle enzyme F/SBPase in reducing conditions, representing a feed-forward activation of the cycle. In oxidizing conditions however, GAP inhibited the enzyme by promoting aggregation. Finally, I will describe efforts in mutagenizing enzymes to reduce sensitivity to metabolite regulation, by high-throughput screening of the effect of enzyme mutation on both cell growth and product synthesis rates.

Proteomics and enzyme engineering Above: A graphical abstract for the presentation. The protein landscape subfigure is from Wittman et al 2019

New publication: Laboratory evolution of cyanobacteria for amino acid overproduction

We were collaborators on a recent paper from the Pia Lindberg group in Uppsala, published in Metabolic Engineering. Nick and Elias contributed with genome re-sequencing of several cyanobacteria strains that had been evolved to tolerate phenylalanine. The more-tolerant strains also produced more phenylalanine. It will be interesting to investigate the molecular mechanisms behind this increased secretion. Screen Shot 2023-08-08 at 3.25.10 PM Laboratory evolution of Synechocystis sp. PCC 6803 for phenylpropanoid production

Conference: 16th Nordic Photosynthesis Congress in Umeå

Paul, Ute, Anna, and Axel attended the 16th Nordic Photosynthesis Congress in Umeå. Paul, Ute, and Anna presented talks and Axel was inspired to do start new projects.

16th NPC

Anna K at NPC 16

IMG 6164

Conference: Metabolic Engineering 15 in Singapore

Rui, Elias, and Emil went to the Marina Bay Sands in Singapore for the Metabolic Engineering 15. Emil and Elias had posters and Rui gave a flash talk on CRISPRi libraries in cyanobacteria.

Rui presenting ME 16 *Rui winning fans in Singapore (blurry) *

ME 16 people


Welcome Elsas Berlin and Hesslow for summer internships

Elsa Berlin and Elsa Hesslow are KTH undergraduate students that joined us for Summer Research Internships. They will help Axel and learn various molecular biology protocols.

Welcome Anna the Third as a visiting Ph.D. student

We welcomed Ph.D. student Anna Wysocka from the lab of Roman Sobotka on a 2-month visit funded by an Erasmus Mobility Grant. Anna III will work on CRISPR/Cas method in Synechocystis.

Group Retreat to Åkersberga

This year our spring retreat was one night in Åkersberga, near the Stockholm archipelago. We ate pizza, drank wine, wondered why the electricity wouldn't work, fixed the electricity, and played some version of Pictionary. Thanks to Party Planning Committee co-chair Emil for arranging the place!

Akersberga 2023

Group picture March 2023

Front (L to R): Nuha, Anna, Weiqi, Paul, Anna II, Ute, Nick Back (L to R): Elias, Ulysse, Nadia, Axel, Gabriel, Emil

Welcome new master students for 2023

This year we welcomed five students to do masters thesis in the group:

  • Anna Schuppe (Stockholm University) will work with Ute on deep mutational scanning and screening of enzymes in cyanobacteria.
  • Ulysse Castet (SciLifeLab MTLS program) will work with Ute on enzyme design projects.
  • Gabriel Salemyr (KTH) will work with Nick on metabolic engineering of Cupriavidus.
  • Julia Ramirez (Stockholm University) will work with Emil and Anna on interaction proteomics.
  • Weiqi Ding (KTH, co-advised by PH) will work with Assoc. Prof. Håkan Jönsson on developing new droplet microfluidics-based assays for secreted products from cyanobacteria.

Anna gas exchange Anna the Second taking cultures for a gas exchange

Welcome Nadia Doge as a visiting Ph.D. student

Nadia joins our lab for a 3 month exchange. Nadia is a Ph.D. student at Copenhagen University working on amino acid secretion in cyanobacteria. Here she will apply proteomics techniques to help study regulation in these pathways.