ATP phosphoribosyltransferase regulatory subunit (IPR004517)

Short name: HisZ

Overlapping homologous superfamilies


Family relationships


Protein in this entry are mostly annotated as the ATP phosphoribosyltransferase regulatory subunit (HisZ). However, this entry also includes some histidine-tRNA ligases (HisS or HisRS), which is the paralogue of HisZ. Despite the significant sequential and structural similarity, HisRS and HisZ have different functions [PMID: 20132829]. HisRS is a class IIa aminoacyl-tRNA synthetase (ligase), while HisZ is a regulatory subunit of the hetero-octameric ATP phosphoribosyl transferase that regulate reactions initiating histidine biosynthesis [PMID: 15660995, PMID: 16051603].

From the phylogenetic analysis, HisZ proteins form a monophyletic group that attaches outside the predominant bacterial HisRS clade [PMID: 10795825]. HisZ are represented in a highly divergent set of bacteria (including an aquificale, cyanobacteria, firmicutes, and proteobacteria), but are missing from other bacteria, including mycrobacteria and certain proteobacteria [PMID: 10795825]. It has been suggested that the absences of HisZ from bacteria are due to its loss during evolution [PMID: 10795825].

GO terms

Biological Process

GO:0000105 histidine biosynthetic process

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0005737 cytoplasm

Contributing signatures

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