Functional insights into protein acetylation in the hyperthermophilic archaeon Sulfolobus islandicus

ABSTRACT: Proteins undergo acetylation at the Nε-amino group of lysine residues and the Nα-amino group of the N-terminus in Archaea as in Bacteria and Eukarya. However, the extent, pattern and roles of the modifications in Archaea remain poorly understood. Here we report the proteomic analyses of a wild-type Sulfolobus islandicus strain and its mutant derivative strains lacking either a homologue of the protein acetyltransferase Pat (SisPat) or a homologue of the Nt-acetyltransferase Ard1 (ΔSisArd1). A total of 1,708 Nε-acetylated lysine residues in 684 proteins (26% of the total proteins), and 158 Nt-acetylated proteins (44% of the identified proteins) were found in S. islandicus. ΔSisArd1 grew more slowly than the parental strain, whereas ΔSisPat showed no significant growth defects. Only 24 out of the 1,503 quantifiable Nε-acetylated lysine residues were differentially acetylated, and all but one of the 24 residues were less acetylated, by >1.3 fold in ΔSisPat than in the parental strain, indicating the narrow substrate specificity of the enzyme. Six acyl-CoA synthetases were the preferred substrates of SisPat in vivo, suggesting that Nε-acetylation by the acetyltransferase is involved in maintaining metabolic balance in the cell. Acetylation of acyl-CoA synthetases by SisPat occurred at a sequence motif conserved among all three domains of life. On the other hand, 92% of the identified N-termini were acetylated by SisArd1 in the cell. The enzyme exhibited broad substrate specificity and was capable of modifying nearly all types of the target N-termini of human NatA-NatF. The deletion of the SisArd1 gene altered the cellular levels of 18% of the quantifiable proteins (1,518) by >1.5 fold. Consistent with the growth phenotype of ΔSisArd1, the cellular levels of proteins involved in cell division and cell cycle control, DNA replication, and purine synthesis were significantly lowered in the mutant than those in the parental strain.

INSTRUMENT(S): Orbitrap Fusion ETD

ORGANISM(S): Sulfolobus Islandicus Rey15a

SUBMITTER: Jingjing Cao  

LAB HEAD: Li Huang

PROVIDER: PXD012246 | Pride | 2019-06-12

REPOSITORIES: Pride