Identification of Nα-acetyl-α-lysine as a probable thermolyte and its accumulation mechanism in Salinicoccus halodurans H3B36

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 N α-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.