How much do mycosporine-like amino acids contribute to UV-B resistance in cyanobacteria? A CRISPR/Cpf1-mediated gene cluster knockout study

How much do mycosporine-like amino acids contribute to UV-B resistance in cyanobacteria? A CRISPR/Cpf1-mediated gene cluster knockout study

Mycosporine-like amino acids (MAAs) function as ultraviolet sunscreens, antioxidants, compatible solutes, and nitrogen reservoirs in diverse organisms. Terrestrial cyanobacteria, such as Nostoc flagelliforme, harbor MAAs and scytonemin within their protective exopolysaccharide envelopes. However, th...

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Main Authors: Xiang Gao, Yue Zhang, Wensheng Liang, Xiaolong Yuan, Hao Xie, Zhengke Li, Lei Wei
Format: Article
Sprog:engelsk
Udgivet: Elsevier 2025-09-01
Serier:The Microbe
Fag:
Cyanobacteria
Ultraviolet-B radiation
Mycosporine-like amino acids
Environmental adaptation
Online adgang:http://www.sciencedirect.com/science/article/pii/S2950194625002249
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Summary:Mycosporine-like amino acids (MAAs) function as ultraviolet sunscreens, antioxidants, compatible solutes, and nitrogen reservoirs in diverse organisms. Terrestrial cyanobacteria, such as Nostoc flagelliforme, harbor MAAs and scytonemin within their protective exopolysaccharide envelopes. However, the extent to which MAAs contribute to UV-B resistance in these cyanobacteria remains largely unclear. Here, we employed the CRISPR/Cpf1-based gene editing to delete the MAA biosynthesis gene cluster in N. flagelliforme to gain insights into the importance of MAAs at the cellular level. The MAA-deficient mutant exhibited heightened sensitivity to UV-B radiation: after 120 min of exposure, its relative activity dropped to 15.0 % under low-intensity UV-B (0.23 W/m²) and 2.5 % under high-intensity UV-B (0.56 W/m²), whereas the wild type retained 52.5 % and 12.9 % of initial activity, respectively. MAA supplementation experiments further validated their remarkable protective role. Additionally, under long-term periodic UV-B exposure (0.35 W/m², 1 h/day for 15 days), the mutant exhibited a faster increase in the carotenoid/chlorophyll a ratio than the wild type, with no significant impairment of biomass growth, indicating photoprotective adjustments. Together, our study suggests that MAAs play a crucial role in the environmental adaptation of terrestrial cyanobacteria, serving as a necessary yet flexible defense mechanism against solar radiation.
ISSN:2950-1946

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