Polyphosphate-kinase-1 dependent polyphosphate hyperaccumulation for acclimation to nutrient loss in the cyanobacterium, Synechocystis sp. PCC 6803

• Published in: Frontiers in plant science 2024-07, Vol.15, p.1441626
• Main Authors: Sato, Norihiro, Endo, Mizuki, Nishi, Hiroki, Fujiwara, Shoko, Tsuzuki, Mikio
• Format: Article
• Language: English
• Subjects: cyanobacteria; Plant Science; polyphosphate; polyphosphate kinase1; PPK1; sulfur starvation; Synechocystis
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2024.1441626

Polyphosphate is prevalent in living organisms. To obtain insights into polyphosphate synthesis and its physiological significance in cyanobacteria, we characterize , a homolog of the polyphosphate-kinase-1 gene, in the freshwater cyanobacterium sp. PCC 6803. The Sll0290 protein structure reveals characteristics of Ppk1. A disruptant and -overexpressing transformant demonstrated loss and gain of polyphosphate synthesis ability, respectively. Accordingly, is identified as . The disruptant (Δ ) grows normally with aeration of ordinary air (0.04% CO ), consistent with its photosynthesis comparable to the wild type level, which contrasts with a previously reported high-CO (5%) requirement for Δ in an alkaline hot spring cyanobacterium, OS-B'. Δ is defective in polyphosphate hyperaccumulation and survival competence at the stationary phase, and also under sulfur-starvation conditions, implying that sulfur limitation is one of the triggers to induce polyphosphate hyperaccumulation in stationary cells. Furthermore, Δ is defective in the enhancement of total phosphorus contents under sulfur-starvation conditions, a phenomenon that is only partially explained by polyphosphate hyperaccumulation. This study therefore demonstrates that in , is not essential for low-CO acclimation but plays a crucial role in dynamic P-metabolic regulation, including polyP hyperaccumulation, to maintain physiological fitness under sulfur-starvation conditions.