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The single tryptophan of the PsbQ protein of photosystem II is at the end of a 4-α-helical bundle domain

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dc.creator Balsera, Mónica
dc.creator Arellano, Juan B.
dc.creator Pazos, Florencio
dc.creator Devos, Damien
dc.creator Valencia, Alfonso
dc.creator De las Rivas, Javier
dc.date 2003-10
dc.date.accessioned 2017-01-31T01:11:13Z
dc.date.available 2017-01-31T01:11:13Z
dc.identifier European Journal of Biochemistry. 270, 3916-3927 (2003)
dc.identifier 10261/4059
dc.identifier 10.1046/j.1432-1033.2003.03774.x
dc.identifier.uri http://dspace.mediu.edu.my:8181/xmlui/handle/123456789/123465
dc.description We examined the microenvironment of the single tryptophan and the tyrosine residues of PsbQ, one of the three main extrinsic proteins of green algal and higher plant photosystem II. On the basis of this information and the previous data on secondary structure [Balsera, M., Arellano, J.B., Gutiérrez, J.R., Heredia, P., Revuelta, J.L. & De Las Rivas, J. (2003) Biochemistry42, 1000–1007], we screened structural models derived by combining various threading approaches. Experimental results showed that the tryptophan residue is partially buried in the core of the protein but still in a polar environment, according to the intrinsic fluorescence emission of PsbQ and the fact that fluorescence quenching by iodide was weaker than that by acrylamide. Furthermore, quenching by cesium suggested that a positively charged barrier shields the tryptophan microenvironment. Comparison of the absorption spectra in native and denaturing conditions indicated that one or two out of six tyrosines of PsbQ are buried in the core of the structure. Using threading methods, a 3D structural model was built for the C-terminal domain of the PsbQ protein family (residues 46–149), while the N-terminal domain is predicted to have a flexible structure. The model for the C-terminal domain is based on the 3D structure of cytochrome b562, a mainly α-protein with a helical up/down bundle folding. Despite the large sequence differences between the template and PsbQ, the structural and energetic parameters for the explicit model are acceptable, as judged by the corresponding tools. This 3D model is compatible with the experimentally determined environment of the tryptophan residue and with published structural information. The future experimental determination of the 3D structure of the protein will offer a good validation point for our model and the technology used. Until then, the model can provide a starting point for further studies on the function of PsbQ.
dc.description This study was supported by funds from the Spanish Ministry of Science and Technology (project PB1998-0480) and the V European Union Framework Programme. M. Balsera holds a fellowship from the Spanish Ministry of Science and Technology.
dc.description Peer reviewed
dc.language eng
dc.publisher Blackwell Publishing
dc.relation http://www3.interscience.wiley.com/journal/118830076/abstract?CRETRY=1&SRETRY
dc.rights openAccess
dc.subject PsbQ
dc.subject Photosystem II
dc.subject Threading
dc.subject 3D model
dc.title The single tryptophan of the PsbQ protein of photosystem II is at the end of a 4-α-helical bundle domain
dc.type Artículo


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