Required for the first step of histidine biosynthesis. May allow the feedback regulation of ATP phosphoribosyltransferase activity by histidine (By similarity). Amino-acid biosynthesis; L-histidine biosynthesis; L-histidine from 5-phospho-alpha-D-ribose 1-diphosphate: step 1/9. Heteromultimer composed of HisG and HisZ subunits. This function is generally fulfilled by the C-terminal part of HisG, which is missing in some bacteria such as this one. Belongs to the class-II aminoacyl-tRNA synthetase family. HisZ subfamily. Truncated N-terminus.