Phosphoribosylformimino-5-aminoimidazole carboxamide ribotide isomerase, HisA. Similar to sprot|HIS4_RALSO (76%) and to sprot|HIS4_AZOBR (52%). Proteins involved in steps 4 and 6 of the histidine biosynthesis pathway are contained in one family. These enzymes are called His6 and His7 in eukaryotes and HisA and HisF in prokaryotes. HisA is a phosphoribosylformimino-5-aminoimidazole carboxamide ribotide isomerase, involved in the fourth step of histidine biosynthesis. TIGRFAM (TIGR00007): phosphoribosylformimino-5-aminoimidazole carboxamide ribotide isomerase Pfam: Histidine biosynthesis [...]

Histidine amidotransferase; IGPS catalyzes the conversion of PRFAR and glutamine to IGP, AICAR and glutamate. The HisH subunit catalyzes the hydrolysis of glutamine to glutamate and ammonia as part of the synthesis of IGP and AICAR. The resulting ammonia molecule is channeled to the active site of HisF.

HisB protein; Imidazoleglycerol-phosphate dehydratase is the enzyme that catalyzes the seventh step in the biosynthesis of histidine in bacteria, fungi and plants. Similar to sprot|HIS7_RALSO (73%) and to sprot|HI7B_ARATH (54%)and to sprot|HIS7_ECOLI (47%). Pfam: IGPD, Imidazoleglycerol-phosphate dehydratase; Specificity unclear.

HisD protein; Catalyzes the sequential NAD-dependent oxidations of L- histidinol to L-histidinaldehyde and then to L-histidine.

Phosphoribosyl-ATP pyrophosphatase, catalyzes the second step in the histidine biosynthetic pathway: 5-phosphoribosyl-ATP + H2O = 5-phosphoribosyl-AMP + PPi Similar to sprot|HIS2_PSEAE (51%) and to sprot|HIS2_AZOBR (43%). Pfam: PRA-PH, Phosphoribosyl-ATP pyrophosphohydrolase; High confidence in function and specificity.

HisG protein; Catalyzes the condensation of ATP and 5-phosphoribose 1- diphosphate to form N'-(5'-phosphoribosyl)-ATP (PR-ATP). Has a crucial role in the pathway because the rate of histidine biosynthesis seems to be controlled primarily by regulation of HisG enzymatic activity. Belongs to the ATP phosphoribosyltransferase family. Short subfamily.

Conserved hypothetical ATP phosphoribosyltransferase regulatory subunit; Required for the first step of histidine biosynthesis. May allow the feedback regulation of ATP phosphoribosyltransferase activity by histidine.

Histidinol-phosphate aminotransferase, hisC. Similar to sprot|HIS8_PSESM (64%). Aminotransferases share certain mechanistic features with other pyridoxal-phosphate dependent enzymes, such as the covalent binding of the pyridoxal-phosphate group to a lysine residue. On the basis of sequence similarity, these various enzymes can be grouped into class I and class II. InterPro (PF00155): Aminotransferase class I and II; High confidence in function and specificity.

Phosphoribosylaminoimidazolecarboxamide formyltransferase/IMP cyclohydrolase; Bifunctional purine biosynthesis protein purH [Includes: Phosphoribosylaminoimidazolecarboxamide formyltransferase (EC 2.1.2.3) (AICAR transformylase); IMP cyclohydrolase (EC 3.5.4.10) (Inosinicase) (IMP synthetase) (ATIC)] InterPro: AICARFT/IMPCHase bienzyme; High confidence in function and specificity.