tRNA N6-adenosine threonylcarbamoyltransferase, TsaD (IPR022450)

Short name: TsaD

Overlapping homologous superfamilies


Family relationships

  • Kae1/TsaD family (IPR017861)
    • tRNA N6-adenosine threonylcarbamoyltransferase, TsaD (IPR022450)


This entry represents the TsaD protein family that is widely distributed. In a few pathogenic species, the protein is exported in a way that may represent an exceptional secondary function. TsaD and its archaeal homologue Kae1 IPR022449 belong to the Kae1/TsaD family IPR017861, a protein family that appears universal in life, and whose broad function is unknown. A member of Kae1 family has been characterised as a DNA-binding protein with apurinic endopeptidase activity. In contrast, the rare characterised members of the TsaD family show O-sialoglycoprotein endopeptidase (EC: activity after export. These include glycoprotease (gcp) from Pasteurella haemolytica A1 and a cohemolysin from Riemerella anatipestifer (GB|AAG39646.1). The member from Staphylococcus aureus is essential and is related to cell wall dynamics and the modulation of autolysis, but members are also found in the Mycoplasmas (which lack a cell wall). A reasonable hypothesis is that virulence-related activities after export are secondary to a bacterial domain-wide unknown function [PMID: 22378793, PMID: 17237169, PMID: 1885539].

TsaD (also known as Gcp or YgjD) was originally described as a glycoprotease essential for cell viability [PMID: 15837383] and a critical mediator involved in the modification of cell wall peptidoglycan synthesis and/or cell division [PMID: 17237169]. Gcp is a member of the Kae1/YgjD family, required for the formation of a threonylcarbamoyl group on adenosine at position 37 in tRNAs that read codons beginning with adenine [PMID: 21285948]. Recently YgjD has been renamed as TsaD, and it has been shown that YgjD and proteins YrdC (TsaC), YjeE (TsaE), and YeaZ (TsaB), are necessary and sufficient for t6A biosynthesis in vitro, and may constitute a complex [PMID: 22378793].

GO terms

Biological Process

GO:0002949 tRNA threonylcarbamoyladenosine modification

Molecular Function

GO:0004222 metalloendopeptidase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.