The LysR‐type transcription factor PacR is a global regulator of photosynthetic carbon assimilation in Anabaena. (8th April 2015)

• Record Type: Journal Article
• Authors: Picossi, Silvia; Flores, Enrique; Herrero, Antonia
• Is Part Of: Environmental microbiology. Volume 17:Number 9(2015:Sep.)
• Page Start: 3341
• Page End: 3351
• Publication Date: 2015-04-08
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12800
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Cyanobacteria perform water‐splitting photosynthesis and are important primary producers impacting the carbon and nitrogen cycles at global scale. They fix CO<sub>2</sub> through ribulose‐bisphosphate carboxylase/oxygenase (RuBisCo) and have evolved a distinct CO<sub>2</sub> concentrating mechanism (CCM) that builds high CO<sub>2</sub> concentrations in the vicinity of RuBisCo favouring its carboxylase activity. Filamentous cyanobacteria such as <italic>A</italic><italic>nabaena</italic> fix CO<sub>2</sub> in photosynthetic vegetative cells, which donate photosynthate to heterocysts that rely on a heterotrophic metabolism to fix N<sub>2</sub>. CCM elements are induced in response to inorganic carbon limitation, a cue that exposes the photosynthetic apparatus to photodamage by over‐reduction. An <italic>A</italic><italic>nabaena</italic> mutant lacking the LysR‐type transcription factor All3953 grew poorly and dies under high light. The <italic>rbcL</italic> operon encoding RuBisCo was induced upon carbon limitation in the wild type but not in the mutant. ChIP‐Seq analysis was used to globally identify All3953 targets under carbon limitation. Targets include, besides <italic>rbcL</italic>, genes encoding CCM elements, photorespiratory pathway‐ photosystem‐ and electron transport‐related components, and factors, including flavodiiron proteins, with a demonstrated or putative function in photoprotection. Quantitative reverse transcription polymerase chain reaction analysis of selected All3953 targets showed regulation in the wild type but not in the mutant. All3953 (PacR) is a global regulator of carbon assimilation in an oxygenic photoautotroph.</p> </abstract>