Affiliation:
1. National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology Chinese Academy of Science 300 Fenglin Road Shanghai 200032 China
Abstract
Summary
The carboxysome plays an essential role in the carbon concentration mechanism in cyanobacteria. Although significant progress has been made in the structural analysis of the carboxysome, little is still known about its biosynthesis.
We identified slr1911, a gene encoding a protein of unknown function in cyanobacterium Synechocystis sp. Strain PCC 6803 (Syn6803), which we termed ccmS by screening a low CO2‐sensitive mutant. CcmS interacts with CcmK1 and CcmM. The former is a shell protein of the β‐carboxysome and the latter is a crucial component of the β‐carboxysome, which is responsible for aggregating RuBisCO and recruiting shell proteins.
The deletion of ccmS lowers the accumulation and assembly of CcmK1, resulting in aberrant carboxysomes, suppressed photosynthetic capacities, and leads to a slow growth phenotype, especially under CO2‐limited conditions.
These observations suggest that CcmS stabilizes the assembly of the β‐carboxysome shell and likely connects the carboxysome core with the shell. Our results provide a molecular view of the role played by CcmS in the formation of the β‐carboxysome and its function in Syn6803.
Funder
Chinese Academy of Sciences