Tracking the flow of water through photosystem II using molecular dynamics and streamline tracing

Serguei Vassiliev, Pascal Comte, Abdullah Mahboob, Doug Bruce

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The CaMn4 cluster of the oxygen-evolving complex (OEC) of photosynthesis catalyzes the lightdriven splitting of water into molecular oxygen, protons, and electrons. The OEC is buried within photosystem II (PSII), a multisubunit integral membrane protein complex, and water must find its way to the CaMn4 cluster by moving through protein. Channels for water entrance, and proton and oxygen exit, have previously been proposed following the analysis of cavities found within X-ray structures of PSII. However, these analyses do not account for the dynamic motion of proteins and cannot track the movement of water within PSII. To study water dynamics in PSII, we performed molecular dynamics simulations and developed a novel approach for the visualization of water diffusion within protein based on a streamline tracing algorithm used in fluid dynamics and diffusion tensor imaging. We identified a system of branching pathways of water diffusion in PSII leading to the OEC that connect to a number of distinct entrance points on the lumenal surface. We observed transient changes in the connections between channels and entrance points that served to moderate both the flow of water near the OEC and the exchange of water inside and outside of the protein. Water flow was significantly altered in simulations lacking the OEC which were characterized by a simpler and wider channel with only two openings, consistent with the creation of an ion channel that allows entry of Mn2+, Ca2+, and Cl- as required for construction of the CaMn4 cluster.

Original languageEnglish
Pages (from-to)1873-1881
Number of pages9
JournalBiochemistry
Volume49
Issue number9
DOIs
Publication statusPublished - Mar 9 2010
Externally publishedYes

Fingerprint

Photosystem II Protein Complex
Flow of water
Molecular Dynamics Simulation
Molecular dynamics
Oxygen
Water
Protons
Proteins
Diffusion tensor imaging
Water Movements
Aquaporins
Diffusion Tensor Imaging
Photosynthesis
Molecular oxygen
Hydrodynamics
Fluid dynamics
Ion Channels
Membrane Proteins
Visualization
X-Rays

ASJC Scopus subject areas

  • Biochemistry

Cite this

Tracking the flow of water through photosystem II using molecular dynamics and streamline tracing. / Vassiliev, Serguei; Comte, Pascal; Mahboob, Abdullah; Bruce, Doug.

In: Biochemistry, Vol. 49, No. 9, 09.03.2010, p. 1873-1881.

Research output: Contribution to journalArticle

Vassiliev, Serguei ; Comte, Pascal ; Mahboob, Abdullah ; Bruce, Doug. / Tracking the flow of water through photosystem II using molecular dynamics and streamline tracing. In: Biochemistry. 2010 ; Vol. 49, No. 9. pp. 1873-1881.
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