Design of a Redox-Linked Active Metal Site:  Manganese Bound to Bacterial Reaction Centers at a Site Resembling That of Photosystem II†,‡

Two D2 mutants were created with a site-directed mutation near the presumable binding site of QA. In one of the mutants, in which Trp-253, the aromatic residue potentially involved in facilitating electron transport from pheophytin to QA and/or in binding of Q A, had been replaced by Leu, PS II was undetectable in thylakoids. This mutant is an obligate photoheterotroph. In another mutant the Gly-215 residue, located next to the His residue that is proposed to bind QA and Fe2+, was mutated to Trp. This mutation leads to a rapid inactivation of oxygen evolution capacity in the light, and to a virtual elimination of the potential to grow photoautotrophically, but does not greatly affect the number of photosystem II reaction centers on a chlorophyll basis. We propose that proper binding of QA to the photosystem II reaction center complex is a prerequisite for stability of the photosystem II complex. Impairment of Q a binding leads to rapid inactivation of photosystem II, which may be followed by a structural disintegration of the complex.

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The evolutionary pathway from anoxygenic to oxygenic photosynthesis examined by comparison of the properties of photosystem II and bacterial reaction centers

Photosynthesis Research ◽

10.1007/s11120-010-9552-x ◽

2010 ◽

Vol 107 (1) ◽

pp. 59-69 ◽

Cited By ~ 24

Author(s):

J. P. Allen ◽

J. C. Williams

Keyword(s):

Photosystem Ii ◽

Reaction Centers ◽

Oxygenic Photosynthesis ◽

Evolutionary Pathway ◽

Bacterial Reaction Centers

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Correlation averaging of ordered arrays of Photosystem II

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129644 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1002-1003

Author(s):

Paul S. Furcinitti ◽

Kathleen M. Marr ◽

Mary K. Lyon

Keyword(s):

Photosystem Ii ◽

Structural Information ◽

Reaction Centers ◽

Two Dimensional ◽

Ps Ii ◽

Bacterial Reaction Centers ◽

Low Concentrations ◽

Molecular Masses ◽

Oxygen Evolving ◽

Triton X

Photosystem II (PS II) is one of two reaction centers found in the photosynthetic membranes of eukaryotic cells. PS II converts solar to chemical energy and can split water, giving off H+ and O2. Neither bacterial reaction centers nor PS I can evolve O2, making PS II unique. Oxygen evolution involves three polypeptides (17, 24 and 33 kDa) that are exposed on the inner surface of the membrane. The remainder of PS II consists of intrinsic membrane proteins with molecular masses of 47, 43, 34, 33 and 10 kDa and multiple low molecular mass polypeptides (for review, see Hansson and Wydrzynski, 1990). In order to obtain structural information regarding PS II, and particularly the oxygen evolving-polypeptides (OEPs), we have induced the complexes to form two-dimensional crystals. The crystals are formed by sequential treatment of whole membranes with low concentrations of Triton X-100. The two-dimensional crystals are tubular, with the complexes arranged in a helical manner around the tube (Fig. 1). The tubes are being characterized by gel electrophoresis and immunoblotting, using antibodies directed against the OEPs.

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