title: Aromatic structure of tyrosine-92 in the extrinsic PsbU protein of red algal photosystem II is important for its functioning.
abstract: PsbU is one of the extrinsic proteins in red algal Photosystem II (PSII) and functions to optimize the availability of Ca(2+) and Cl(-) cofactors for water oxidation. To determine the functional residue of PsbU, we constructed various PsbU mutants from a red alga Cyanidium caldarium and reconstituted these mutants with the red algal PSII. The results revealed that Tyr-92 of PsbU, especially its aromatic ring, was essential for maintaining its function. From the crystal structure of PSII, Tyr-92 is located close to Pro-340 of D1, suggesting that the aromatic ring of Tyr-92 interacts with the CH group of Pro-340 of D1, and this CH/pi interaction is important for the optimal function of the Mn(4)Ca-cluster.
authors.affiliation: Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University, Tokyo 156-8850, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Okumura
authors.forename: Masanori
authors.initials: M
authors.lastname: Sano
authors.forename: Takehiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Ryo
authors.initials: R
authors.lastname: Nagao
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Nakazato
authors.forename: Masako
authors.initials: M
authors.lastname: Iwai
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Adachi
authors.forename: Jian-Ren
authors.initials: JR
authors.lastname: Shen
authors.forename: Isao
authors.initials: I
authors.lastname: Enami
mesh_terms: D020418:Algal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000461:Rhodophyta / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000737:chemistry; D014867:Water / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D002712:Chlorides; D045332:Photosystem II Protein Complex; D014867:Water; D014443:Tyrosine; D010100:Oxygen; D002118:Calcium