Abstract
Salinicoccus halodurans H3B36 is a moderate halophile that was isolated from a 3.2-m-deep sediment sample in Qaidam Basin, China. Our results suggest that Nα-acetyl-α-lysine can accumulate and act as a probable thermolyte in this strain. The accumulation mechanism and biosynthetic pathway for this rare compatible solute were also elucidated. We confirmed that the de novo synthesis pathway of Nα-acetyl-α-lysine in this strain starts from aspartate and passes through lysine. Through RNA sequencing, we also found an 8-gene cluster (orf_1582–1589) and another gene (orf_2472) that might encode the biosynthesis of Nα-acetyl-α-lysine in S. halodurans H3B36. Orf_192, orf_193, and orf_1259 might participate in the transportation of precursors for generating Nα-acetyl-α-lysine under the heat stress. The transcriptome reported here also generated a global view of heat-induced changes and yielded clues for studying the regulation of Nα-acetyl-α-lysine accumulation. Heat stress triggered a global transcriptional disturbance and generated a series of actions to adapt the strain to heat stress. Furthermore, the transcriptomic results showed that the regulon of RpoN (orf_2534) may be critical to conferring heat stress tolerance and survival to S. halodurans.
Highlights
Salinicoccus halodurans H3B36 is a moderate halophile that was isolated from a 3.2-m-deep sediment sample in Qaidam Basin, China
We found that Salinicoccus halodurans H3B36, which was isolated from a sediment sample (3.2 m deep) in the Qaidam Basin, can accumulate Nα-acetyl-α-lysine acting as an organic cytoprotectant
According to the retention times of standard substances monitored by photodiode array detector (DAD) and refractive index detector (RID) and the related chemical shifts in the natural abundance 13C-nuclear magnetic resonance spectroscopy (NMR) spectrum, glycine betaine and an unknown osmoprotectant were found to be accumulated in strain H3B36
Summary
Salinicoccus halodurans H3B36 is a moderate halophile that was isolated from a 3.2-m-deep sediment sample in Qaidam Basin, China. The term “compatible solute” refers to low-molecular-weight, water-soluble, organic compounds that the cell can accumulate through de novo synthesis or external uptake in exceedingly high concentrations under extreme conditions, such as osmotic, heat or cold stress, without affecting enzyme activity or cell metabolism[5,6]. We found that Salinicoccus halodurans H3B36, which was isolated from a sediment sample (3.2 m deep) in the Qaidam Basin, can accumulate Nα-acetyl-α-lysine acting as an organic cytoprotectant. This substance exhibited heat stress-relieving properties, and its concentration increased by several fold when the cultivation temperature was raised. C13-labelling experiments and transcriptomic analysis were employed to explore the Nα-acetyl-α-lysine accumulative mechanism and gain a broad understanding of the molecular basis of heat acclimation in S. halodurans H3B36
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