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bioRxiv · 10.1101/086090

Super-resolution microscopy of the β-carboxysome reveals a homogenous matrix

Niederhuber, M. J.·Lambert, T. J.·Yapp, C.·Silver, P. A.·Polka, J. K.
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Abstract

Carbon fixation in cyanobacteria makes a major contribution to the global carbon cycle. The cyanobacterial carboxysome is a proteinaceous microcompartment that protects and concentrates the carbon-fixing enzyme RuBisCO in a paracrystalline lattice, making it possible for these organisms to fix CO2 from the atmosphere. The protein responsible for the organization of this lattice in beta-type carboxysomes of the freshwater cyanobacterium Synechococcus elongatus, CcmM, occurs in two isoforms thought to localize differentially within the carboxysome matrix. Here we use widefield timelapse and 3D-structured illumination microscopy (3D-SIM) to study the recruitment and localization of these two isoforms. We demonstrate that this super-resolution technique is capable of successfully resolving the outer protein shell of the carboxysome from its internal cargo. We develop an automated analysis pipeline to analyze and quantify 3D-SIM images and generate a population level description of carboxysome shell protein, RuBisCO, and CcmM isoform localization. We find that both CcmM isoforms colocalize in space and time, prompting a revised model of the internal arrangement of the beta carboxysome.

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Niederhuber, M. J., Lambert, T. J., Yapp, C., Silver, P. A., Polka, J. K.. 2016-11-23. Super-resolution microscopy of the β-carboxysome reveals a homogenous matrix. https://doi.org/10.1101/086090

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