Membrane protein targeting and assembly in cyanobacteria

Lead Research Organisation: University of Liverpool
Department Name: Institute of Integrative Biology

Abstract

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Technical Summary

The thylakoids of cyanobacteria are intracytoplasmic membranes that are the sole site of the photosynthetic light reactions and the major site of respiration. Their proteome is strikingly different from that of the plasma membrane. Cyanobacterial membrane targeting systems have never been resolved, and the sites of translation and membrane insertion remain controversial. Using Fluorescent in situ Hybridisation (RNA-FISH), we found that mRNAs encoding core photosynthetic proteins cluster at thylakoid surfaces, suggesting that there are highly localised thylakoid translation zones. We found that thylakoid association persists even when the mRNA is decoupled from the ribosomes, indicating a ribosome-independent mechanism for locating photosynthetic mRNAs to the thylakoid surface. We identified two RNA-binding proteins (RBPs) that are important for locating photosynthetic mRNAs. Now, we will use similar techniques to fully define the role of the thylakoid translation zones. We will test whether different photosynthetic proteins are produced at the same zones, or whether each protein has its own specific translation zone. We will test whether the newly-produced photosynthetic complexes stay at the translation zones, or whether they migrate elsewhere in the membrane for further assembly. We will use Atomic Force Microscopy to probe the membrane landscape of the thylakoid translation zones, which we expect to give new insights into reaction centre assembly. We will probe the translation sites of membrane-integral plasma membrane proteins and we will test for the involvement of further RBPs in targeting mRNA molecules to the thylakoid and the plasma membranes, We will look for features of the mRNA molecules that may be recognised by each of the RBPs and we will test these ideas by mutating the mRNA sequences. This will lead towards methods for specific membrane targeting of heterologous proteins and "precision engineering" of cyanobacteria for solar-powered biotechnology.

Publications

10 25 50
 
Description characterise the molecular process of photosynthetic system biosynthsis, informing engineering of photosynthetic systems for bioenergy production
Exploitation Route fundamental knowledge of photosynthetic membrane and system development
Sectors Agriculture

Food and Drink

Education

Energy

 
Description potential societal impacts on renewable energy and energy security
First Year Of Impact 2023
Sector Agriculture, Food and Drink,Education,Energy
Impact Types Societal

 
Description TM - Mullineaux 
Organisation Queen Mary University of London
Department School of Biological and Chemical Science QMUL
Country United Kingdom 
Sector Academic/University 
PI Contribution generating cyanobacterial mutants
Collaborator Contribution electron transport activity and optical spectrum analysis
Impact The collaboration has led to a paper published (Casella S, Huang F, Mason D, Zhao GY, John GN, Mullineaux CW, Liu LN*. Dissecting the native architecture and dynamics of cyanobacterial photosynthetic machinery. Molecular Plant, 2017, 10: 1434-1448. DOI:http://dx.doi.org/10.1016/j.molp.2017.09.019). The preliminary collaborative work has helped to secure a BBSRC grant (BB/R003890/1).
Start Year 2015
 
Description photosynthetic membrane organisation Melih Sener 
Organisation Arizona State University
Country United States 
Sector Academic/University 
PI Contribution MD simulations of photosynthetic membranes
Collaborator Contribution MD simulations
Impact N/A
Start Year 2023
 
Description photosynthetic membrane organisation Michal Koblizek 
Organisation Academy of Sciences of the Czech Republic
Department Institute of Microbiology
Country Czech Republic 
Sector Academic/University 
PI Contribution AFM imaging of photosynthetic membranes
Collaborator Contribution providing photosynthetic membranes
Impact N/A
Start Year 2023
 
Description Gordon Research Conference on Photosynthesis 2023 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact RESEARCH SEMINAR AT GORDON CONFERENCE IN US
Year(s) Of Engagement Activity 2023
URL https://www.grc.org/photosynthesis-conference/2023/#:~:text=The%20Photosynthesis%20GRC%20is%20a,scie...