Recent Advances in Biological Functions of Thick Pili in the Cyanobacterium Synechocystis sp. PCC 6803

Abstract

Cyanobacteria have evolved various strategies to sense and adapt to biotic and abiotic stresses including active movement. Motility in cyanobacteria utilizing the type IV pili (TFP) is useful to cope with changing environmental conditions. The model cyanobacterium Synechocystis sp. PCC 6803 (hereafter named Synechocystis) exhibits motility via TFP called thick pili, and uses it to seek out favorable light/nutrition or escape from unfavorable conditions. Recently, a number of studies on Synechocystis thick pili have been undertaken. Molecular approaches support the role of the pilin in motility, cell adhesion, metal utilization, and natural competence in Synechocystis. This review summarizes the most recent studies on the function of thick pili as well as their formation and regulation in this cyanobacterium.

Type IV Pili-Independent Photocurrent Production by the Cyanobacterium Synechocystis sp. PCC 6803

“…Synechocystis has also been reported to produce conductive filaments under conditions of CO 2 limitation (Gorby et al, 2006), although whether these are Tfp is unclear. For detailed reviews of Tfp structure, biogenesis, and function in Synechocystis, see Schuergers and Wilde (2015) and Chen et al (2020).…”

Hik36–Hik43 and Rre6 act as a two-component regulatory system to control cell aggregation in Synechocystis sp. PCC6803

“…PCC6803 (hereafter Synechocystis) does not possess flagella. Instead, Synechocystis possesses pili that mediate cell motility required for adherence, biofilm formation and locomotion 8 . This system resembles the flagellar signal transduction pathway and has been extensively studied in Pseudomonas aeruginosa 9 .…”

Function and Benefits of Natural Competence in Cyanobacteria: From Ecology to Targeted Manipulation

“…However, this needs experimental validation. Additionally, it has been suggested that the outer membrane pore-forming secretin PilQ, through which the DNA is translocated into the periplasm, may directly be involved in DNA binding [ 44 ].…”

“…Once the DNA has been pulled into the periplasm, one DNA strand is degraded whilst the other is translocated further across the cytoplasmic membrane through the action of ComAEF [ 1 , 16 , 44 ]. In cyanobacteria, the exact function of each of these proteins is poorly understood.…”

“…Expressing the molecular machinery required for natural competence is costly. The cost of T4P formation can, however, be offset to some extent, given its functions across a wide range of important cellular mechanisms [ 34 , 35 , 44 ]. Sharing the cost for T4P formation means that the cost for natural competence itself is significantly reduced to mainly the Com proteins.…”