Systems analysis of the CO2 concentrating mechanism in cyanobacteria

  1. Niall Mangan  Is a corresponding author
  2. Michael Brenner
  1. Massachusetts Institute of Technology, United States
  2. Harvard University, United States


Cyanobacteria are photosynthetic bacteria with a unique CO2 concentrating mechanism (CCM), enhancing carbon fixation. Understanding the CCM requires a systems level perspective of how molecular components work together to enhance CO2 fixation. We present a mathematical model of the cyanobacterial CCM, giving the parameter regime (expression levels, catalytic rates, permeability of carboxysome shell) for efficient carbon fixation. Efficiency requires saturating the RuBisCO reaction, staying below saturation for carbonic anhydrase, and avoiding wasteful oxygenation reactions. We find selectivity at the carboxysome shell is not necessary; there is an optimal non-specific carboxysome shell permeability. We compare the efficacy of facilitated CO2 uptake, CO2 scavenging, and HCO3- transport with varying external pH. At the optimal carboxysome permeability, contributions from CO2 scavenging at the cell membrane are small. We examine the cumulative benefits of CCM spatial organization strategies: enzyme co-localization and compartmentalization.

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Author details

  1. Niall Mangan

    Massachusetts Institute of Technology, Cambridge, MA, United States
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
  2. Michael Brenner

    Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Ron Milo, Weizmann, Israel

Version history

  1. Received: December 11, 2013
  2. Accepted: April 12, 2014
  3. Accepted Manuscript published: April 29, 2014 (version 1)
  4. Version of Record published: May 20, 2014 (version 2)


© 2014, Mangan et al.

This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.


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  1. Niall Mangan
  2. Michael Brenner
Systems analysis of the CO2 concentrating mechanism in cyanobacteria
eLife 3:e02043.

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