Cyanophycin Modifications—Widening the Application Potential

Abstract

A circular bioeconomy approach is essential to slowing down the fearsome ongoing climate change. Replacing polymers derived from fossil fuels with biodegradable biobased polymers is one crucial part of this strategy. Cyanophycin is a polymer consisting of amino acids produced by cyanobacteria with many potential applications. It consists mainly of aspartic acid and arginine, however, its composition may be changed at the production stage depending on the conditions of the polymerization reaction, as well as the characteristics of the enzyme cyanophycin synthetase, which is the key enzyme of catalysis. Cyanophycin synthetases from many sources were expressed heterologously in bacteria, yeast and plants aiming at high yields of the polymer or at introducing different amino acids into the structure. Furthermore, cyanophycin can be modified at the post-production level by chemical and enzymatic methods. In addition, cyanophycin can be combined with other compounds to yield hybrid materials. Although cyanophycin is an attractive polymer for industry, its usage as a sole material remains so far limited. Finding new variants of cyanophycin may bring this polymer closer to real-world applications. This short review summarizes all modifications of cyanophycin and its variants that have been reported within the literature until now, additionally addressing their potential applications.

Heterologous production of cyanophycin withTatumella morbiroseicyanophycin synthetase

“…Cyanophycin has a natural size range from 20-100 kDa, with heterologous production in E. coli usually generating nearer to 20-40 kDa [24]. Here, cyanophycin produced in vitro by purified TmCphA1 showed a size distribution of between 20-30 kDa, similar to what has been shown previously for TmCphA1 [3] and other CphA1 enzymes [15,[25][26][27][28].…”

“…A total of 1.80 g of insoluble cyanophycin and 0.12 g of soluble cyanophycin were recovered, which represented a significant improvement over the 1.14 g of insoluble cyanophycin and 0.18 g of soluble cyanophycin produced by the same strain in a 1 L shake flask (where growth reached an OD 600 of only 11.8). Furthermore, the yields of both insoluble and total cyanophycin from Tm CphA1 exceed that which has been reported for other, more commonly studied variants during bench-scale bioreactor production [15]. For comparison, when we applied the same bioreactor conditions for cyanophycin production by E. coli harboring 6308 CphA1, only 0.20 g of insoluble material was recovered.…”

“…The role of the M domain (often compared with Mur ligases) is to add arginine to the sidechain of the recently-added aspartic acid residue, again with the use of ATP [14]. The N domain is thought to use salt bridges and hydrogen bonding to loosely anchor the cyanophycin molecule in place, supporting a “flip-flop” mechanism where the polymer rebounds from the G domain to the M domain and back, allowing individual subunits to be alternately attached to the growing polymer chain [3, 15]. The N domain of most CphA1 enzymes has also recently been shown to generate primers, which are used to initiate cyanophycin synthesis in vivo , though Tm CphA1 is among the minority of CphA1 enzymes whose N domain lacks this active site [16].…”

Sustainable Production of the Cyanophycin Biopolymer in Tobacco in the Greenhouse and Field

“…Accordingly, plant-based CGP has considerable market potential, especially in Argentina and other Latin American countries with a substantial amount of tobacco production, and can facilitate the development of a sustainable bioeconomy ( Trigo et al, 2021 ). Nevertheless, this product must compete with CGP derived from cyanobacteria ( Lippi et al, 2018 ), or synthesized from Escherichia coli or yeast ( Sallam et al, 2011 ).which all represents active areas of research Certain commercial success has been achieved with synthesis based on Escherichia coli ( Kwiatos and Steinbüchel, 2021 ).…”

Recombinant Multi‐l‐Arginyl‐Poly‐l‐Aspartate (Cyanophycin) as an Emerging Biomaterial

“…[10] In the past, a number of reviews have provided extensive insight on the cloning and microbial expression systems of cphA gene for MAPA production and metabolism. [5,[11][12][13][14] This short review focuses on the recent findings of cyanophycin synthetase and the potential applications of MAPA as a biomaterial.…”