Project description:Nα -acetyl-α-lysine was found as a new type of compatible solutes that acted as an organic cytoprotectant in the strain of Salinicoccus halodurans H3B36. A novel lysine Nα -acetyltransferase gene (shkat), encoding an enzyme that catalysed the acetylation of lysine exclusively at α position, was identified from this moderate halophilic strain and expressed in Escherichia coli. Sequence analysis indicated ShKAT contained a highly conserved pyrophosphate-binding loop (Arg-Gly-Asn-Gly-Asn-Gly), which was a signature of the GNAT superfamily. ShKAT exclusively recognized free amino acids as substrate, including lysine and other basic amino acids. The enzyme showed a wide range of optimal pH value and was tolerant to high-alkali and high-salinity conditions. As a new member of the GNAT superfamily, the ShKAT was the first enzyme recognized free lysine as substrate. We believe this work gives an expanded perspective of the GNAT superfamily, and reveals great potential of the shkat gene to be applied in genetic engineering for resisting extreme conditions.
Project description:Salinicoccus halodurans H3B36 is a moderately halophilic bacterium isolated from a sediment sample of Qaidam Basin at 3.2 m vertical depth. Strain H3B36 accumulate N (α)-acetyl-α-lysine as compatible solute against salinity and heat stresses and may have potential applications in industrial biotechnology. In this study, we sequenced the genome of strain H3B36 using single molecule, real-time sequencing technology on a PacBio RS II instrument. The complete genome of strain H3B36 was 2,778,379 bp and contained 2,853 protein-coding genes, 12 rRNA genes, and 61 tRNA genes with 58 tandem repeats, six minisatellite DNA sequences, 11 genome islands, and no CRISPR repeat region. Further analysis of epigenetic modifications revealed the presence of 11,000 m4C-type modified bases, 7,545 m6A-type modified bases, and 89,064 other modified bases. The data on the genome of this strain may provide an insight into the metabolism of N (α)-acetyl-α-lysine.