3ZSU

Structure of the CyanoQ protein from Thermosynechococcus elongatus

Summary for 3ZSU

• Entry DOI: 10.2210/pdb3zsu/pdb
• Descriptor: TLL2057 PROTEIN, SULFATE ION (3 entities in total)
• Functional Keywords: photosystem ii assembly, photosynthesis, extrinsic protein
• Biological source: THERMOSYNECHOCOCCUS ELONGATUS
• Total number of polymer chains: 1
• Total formula weight: 14480.10

Authors

Michoux, F.,Takasaka, K.,Nixon, P.J.,Murray, J.W. (deposition date: 2011-06-30, release date: 2012-06-13, Last modification date: 2023-12-20)

Primary citation

Michoux, F.,Boehm, M.,Bialek, W.,Takasaka, K.,Maghlaoui, K.,Barber, J.,Murray, J.W.,Nixon, P.J.
Crystal Structure of Cyanoq from the Thermophilic Cyanobacterium Thermosynechococcus Elongatus and Detection in Isolated Photosystem II Complexes.
Photosynth.Res., 122:57-, 2014

PubMed Abstract: The PsbQ-like protein, termed CyanoQ, found in the cyanobacterium Synechocystis sp. PCC 6803 is thought to bind to the lumenal surface of photosystem II (PSII), helping to shield the Mn4CaO5 oxygen-evolving cluster. CyanoQ is, however, absent from the crystal structures of PSII isolated from thermophilic cyanobacteria raising the possibility that the association of CyanoQ with PSII might not be a conserved feature. Here, we show that CyanoQ (encoded by tll2057) is indeed expressed in the thermophilic cyanobacterium Thermosynechococcus elongatus and provide evidence in support of its assignment as a lipoprotein. Using an immunochemical approach, we show that CyanoQ co-purifies with PSII and is actually present in highly pure PSII samples used to generate PSII crystals. The absence of CyanoQ in the final crystal structure is possibly due to detachment of CyanoQ during crystallisation or its presence in sub-stoichiometric amounts. In contrast, the PsbP homologue, CyanoP, is severely depleted in isolated PSII complexes. We have also determined the crystal structure of CyanoQ from T. elongatus to a resolution of 1.6 Å. It lacks bound metal ions and contains a four-helix up-down bundle similar to the ones found in Synechocystis CyanoQ and spinach PsbQ. However, the N-terminal region and extensive lysine patch that are thought to be important for binding of PsbQ to PSII are not conserved in T. elongatus CyanoQ.

PubMed: 24838684
DOI: 10.1007/S11120-014-0010-Z

Experimental method

X-RAY DIFFRACTION (1.6 Å)