Photoautotrophic growth of Synechocystis sp. PCC 6803 in a flat-panel photobioreactor, run in turbidostat mode under increasing intensities of orange-red light (636 nm), showed a maximal growth rate (0.12 h⁻¹) at 300 μmol_photons m⁻² s⁻¹, whereas first signs of photoinhibition were detected above 800 μmol_photons m⁻² s⁻¹. To investigate the dynamic modulation of the thylakoid proteome in response to photoinhibitory light intensities, quantitative proteomics analyses by SWATH mass spectrometry were performed by comparing thylakoid membranes extracted from Synechocystis grown under low-intensity illumination (i.e. 50 μmol_photons m⁻² s⁻¹) with samples isolated from cells subjected to photoinhibitory light regimes (800, 950 and 1460 μmol_photons m⁻² s⁻¹). We identified and quantified 126 proteins with altered abundance in all three photoinhibitory illumination regimes.

These data reveal ...

A.Cordara, M.Manfredi,  P. Alphen,  E. Marengo,  R.Pirone, G.Saracco, F.Branco dos Santos,  K .J. Hellingwerf,  C.Pagliano

Synechocystis gathered momentum in modelling studies and biotechnological applications owing to multiple factors like fast growth, ability to fix carbon dioxide into valuable products, and the relative ease of genetic manipulation. Synechocystis physiology and metabolism, and consequently, the productivity of Synechocystis-based photobioreactors (PBRs), are heavily light modulated. Here, we set up a turbidostat-controlled lab-scale cultivation system in order to study the influence of varying orange–red light intensities on Synechocystis growth characteristics and photosynthetic activity. Synechocystis growth and photosynthetic activity were found to raise as supplied light intensity increased up to 500 μmol photons m⁻² s⁻¹ and to enter the photoinhibition state only at 800 μmol photons m⁻² s⁻¹. Interestingly, reverting the light to a non-photo-inhibiting intensity unveiled Synechocystis to be able to promptly recover. Furthermore...

A.Cordara, A.Re, C.Pagliano, P.Van Alphen, R. Pirone, G. Saracco, F. Branco dos Santos, K.J. Hellingwerf, N.Vasile

We have identified and characterized the AccS multidomain sensor kinase that mediates the activation of the AccR master regulator involved in carbon catabolite repression (CCR) of the anaerobic catabolism of aromatic compounds in Azoarcus sp. CIB. A truncated AccS protein that contains only the soluble C-terminal autokinase module (AccS′) accounts for the succinate-dependent CCR control. In vitro assays with purified AccS′ revealed its autophosphorylation, phosphotransfer from AccS′∼P to the Asp60 residue of AccR, and the phosphatase activity toward its phosphorylated response regulator, indicating that the equilibrium between the kinase and phosphatase activities of AccS′ may control the phosphorylation state of the AccR transcriptional regulator. Oxidized quinones...

J. Andrés Valderrama, Helena Gómez-Álvarez, Zaira Martín-Moldes, M. Álvaro Berbís, F. Javier Cañada, Gonzalo Durante-Rodríguez, Eduardo Díaz