Light-induced H 2 generation in a photosystem I-O 2 -tolerant [FeFe] hydrogenase nanoconstruct

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 121; no. 34; p. e2400267121
• Main Authors: Rumbaugh, Tristen D, Gorka, Michael J, Baker, Carol S, Golbeck, John H, Silakov, Alexey
• Format: Journal Article
• Language: English
• Published: United States 20-08-2024
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Clostridium beijerinckii - genetics; Clostridium beijerinckii - metabolism; Hydrogen - metabolism; Hydrogenase - chemistry; Hydrogenase - metabolism; Iron-Sulfur Proteins - chemistry; Iron-Sulfur Proteins - metabolism; Light; Oxidation-Reduction; Oxygen - chemistry; Oxygen - metabolism; Photosynthesis; Photosystem I Protein Complex - chemistry; Photosystem I Protein Complex - metabolism; protein fusion; Photosystem I; PsaE; hydrogenase; dihydrogen generation
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2400267121

The fusion of hydrogenases and photosynthetic reaction centers (RCs) has proven to be a promising strategy for the production of sustainable biofuels. Type I (iron-sulfur-containing) RCs, acting as photosensitizers, are capable of promoting electrons to a redox state that can be exploited by hydrogenases for the reduction of protons to dihydrogen (H
). While both [FeFe] and [NiFe] hydrogenases have been used successfully, they tend to be limited due to either O
sensitivity, binding specificity, or H
production rates. In this study, we fuse a peripheral (stromal) subunit of Photosystem I (PS I), PsaE, to an O
-tolerant [FeFe] hydrogenase from
using a flexible [GGS]
linker group (
HydA1-PsaE). We demonstrate that the
HydA1 chimera can be synthetically activated in vitro to show bidirectional activity and that it can be quantitatively bound to a PS I variant lacking the PsaE subunit. When illuminated in an anaerobic environment, the nanoconstruct generates H
at a rate of 84.9 ± 3.1 µmol H
mg
h
. Further, when prepared and illuminated in the presence of O
, the nanoconstruct retains the ability to generate H
, though at a diminished rate of 2.2 ± 0.5 µmol H
mg
h
. This demonstrates not only that PsaE is a promising scaffold for PS I-based nanoconstructs, but the use of an O
-tolerant [FeFe] hydrogenase opens the possibility for an in vivo H
generating system that can function in the presence of O
.