PXD061921

PXD061921 is an original dataset announced via ProteomeXchange.

Title	Probing substrate water access through the O1 channel of Photosystem II by single site mutations and membrane inlet mass spectrometry
Description	Light-driven water oxidation by photosystem II sustains life on Earth by providing the electrons and protons for the reduction of CO2 to carbohydrates and the molecular oxygen we breathe. The inorganic core of the oxygen evolving complex is made of the earth-abundant elements manganese, calcium and oxygen (Mn4CaO5 cluster), and is situated in a binding pocket that is connected to the aqueous surrounding via water-filled channels that allow water intake and proton egress. Recent serial crystallography and infrared spectroscopy studies performed with PSII isolated from Thermosynechococcus vestitus (T. vestitus) support that one of these channels, the O1 channel, facilitates water access to the Mn4CaO5 cluster during its S2 - S3 and S3 - S4 - S0 state transitions, while a subsequent CryoEM study concluded that this channel is blocked in the cyanobacterium Synechocystis sp. PCC 6803, questioning the role of the O1 channel in water delivery. Employing site-directed mutagenesis we modified the two O1 channel bottleneck residues D1-E329 and CP43-V410 (T. vestitus numbering) and probed water access and substrate exchange via time resolved membrane inlet mass spectrometry. Our data demonstrates that water reaches the Mn4CaO5 cluster via the O1 channel in both wildtype and mutant PSII. In addition, the detailed analysis provides functional insight into the intricate protein-water-cofactor network near the Mn4CaO5 cluster that includes the pentameric, near planar ‘water wheel’ of the O1 channel.
HostingRepository	PRIDE
AnnounceDate	2025-05-07
AnnouncementXML	Submission_2025-05-07_07:28:36.292.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Shaochun Zhu
SpeciesList	scientific name: Synechocystis sp. (strain PCC 6803 / Kazusa); NCBI TaxID: 1111708;
ModificationList	No PTMs are included in the dataset
Instrument	Orbitrap Exploris 480

Revision	Datetime	Status	ChangeLog Entry
0	2025-03-17 07:24:04	ID requested
⏵ 1	2025-05-07 07:28:37	announced

10.1007/s11120-025-01147-4;

Aydin AO, de Lichtenberg C, Liang F, Forsman J, Gra, ç, a AT, Chernev P, Zhu S, Mateus A, Magnuson A, Cheah MH, Schr, ö, der WP, Ho F, Lindblad P, Debus RJ, Mamedov F, Messinger J, Probing substrate water access through the O1 channel of Photosystem II by single site mutations and membrane inlet mass spectrometry. Photosynth Res, 163(3):28(2025) [pubmed]

submitter keyword: photosystem II, mass spectrometry,Thermosynechococcus vestitus, O1 channel

Johannes Messinger
contact affiliation	Molecular Biomimetics, Department of Chemistry – Ångström, Uppsala University, 751 20 Uppsala, Sweden Umeå Plant Science Center (UPSC), Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden
contact email	johannes.messinger@umu.se
lab head
Shaochun Zhu
contact affiliation	Umea University
contact email	shaochunzhu@gmail.com
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD061921
     1. Label: PRIDE project
     2. Name: Probing substrate water access through the O1 channel of Photosystem II by single site mutations and membrane inlet mass spectrometry