HisB

The hisB gene, found in the enterobacteria (such as E. coli), in Campylobacter jejuni and in Xylella/Xanthomonas encodes a protein involved in catalysis of two step in histidine biosynthesis (the sixth and eight step), namely the bifunctional Imidazoleglycerol-phosphate dehydratase/histidinol-phosphatase.[1]

The former function (EC 4.2.1.19), found at the N-terminal, dehydrated d-erythroimidazoleglycerolphosphate to imidazoleacetolphosphate, the latter function (EC 3.1.3.15), found at the C-terminal, dephosphorylates l-histidinolphosphate producing histidinol.[2][3][4]

The firth step is catalysed instead by histadinolphosphate aminotransferase (encoded by hisC)[5]

The peptide is 40.5kDa and associates to form a hexamer (unless truncated)[6]

In E. coli hisB is found on the hisGDCBHAFI operon[7]

The phosphatase activity possess a substrate ambiguity and overexpression of hisB can rescue phosphoserine phosphatase (serB) knockouts.[8]

Reactions

hisB-N

D-erythro-1-(imidazol-4-yl)glycerol 3-phosphate ${\displaystyle \rightleftharpoons }$ 3-(imidazol-4-yl)-2-oxopropyl phosphate + H₂O

hisB-C

L-histidinol phosphate + H₂O ${\displaystyle \rightleftharpoons }$ L-histidinol + phosphate

Non-fusion protein in other species

HIS3 from Saccharomyces cerevisiae is not a fused IGP dehydratase and hisidinol phosphatase, but an IGPD only (homologous to hisB-N). Whereas HIS2 is the HP (analogous to hisB-C, called hisJ in some prokaryotes).

References

1. Brilli, M.; Fani, R. (2004). "Molecular Evolution of hisB Genes". Journal of Molecular Evolution. 58 (2): 225–237. Bibcode:2004JMolE..58..225B. doi:10.1007/s00239-003-2547-x. PMID 15042344. S2CID 1684458.
2. Parker95: Parker, A.R., Moore, J.A., Schwab, J.M., Davisson, V.J. (1995). "Escherichia coli Imidazoleglycerol Phosphate Dehydratase: Spectroscopic Characterization of the Enzymic Product and the Steric Course of the Reaction." Journal of the American Chemical Society.
3. Grisolia, V.; Carlomagno, M. S.; Bruni, C. B. (1982). "Cloning and expression of the distal portion of the histidine operon of Escherichia coli K-12". Journal of Bacteriology. 151 (2): 692–700. doi:10.1128/jb.151.2.692-700.1982. PMC 220310. PMID 6284708.
4. Grisolia, V.; Riccio, A.; Bruni, C. B. (1983). "Structure and function of the internal promoter (hisBp) of the Escherichia coli K-12 histidine operon". Journal of Bacteriology. 155 (3): 1288–1296. doi:10.1128/jb.155.3.1288-1296.1983. PMC 217827. PMID 6309747.
5. Keseler, I. M.; Collado-Vides, J.; Santos-Zavaleta, A.; Peralta-Gil, M.; Gama-Castro, S.; Muñiz-Rascado, L.; Bonavides-Martinez, C.; Paley, S.; Krummenacker, M.; Altman, T.; Kaipa, P.; Spaulding, A.; Pacheco, J.; Latendresse, M.; Fulcher, C.; Sarker, M.; Shearer, A. G.; MacKie, A.; Paulsen, I.; Gunsalus, R. P.; Karp, P. D. (2010). "EcoCyc: A comprehensive database of Escherichia coli biology". Nucleic Acids Research. 39 (Database issue): D583 – D590. doi:10.1093/nar/gkq1143. PMC 3013716. PMID 21097882.
6. Rangarajan, E. S.; Proteau, A.; Wagner, J.; Hung, M. -N.; Matte, A.; Cygler, M. (2006). "Structural Snapshots of Escherichia coli Histidinol Phosphate Phosphatase along the Reaction Pathway". Journal of Biological Chemistry. 281 (49): 37930–37941. doi:10.1074/jbc.M604916200. PMID 16966333.
7. Alifano, P.; Carlomagno, M. S.; Bruni, C. B. (1992). "Location of the hisGDCBHAFI operon on the physical map of Escherichia coli". Journal of Bacteriology. 174 (11): 3830–3831. doi:10.1128/jb.174.11.3830-3831.1992. PMC 206079. PMID 1592835.
8. Patrick, W. M.; Quandt, E. M.; Swartzlander, D. B.; Matsumura, I. (2007). "Multicopy Suppression Underpins Metabolic Evolvability". Molecular Biology and Evolution. 24 (12): 2716–2722. doi:10.1093/molbev/msm204. PMC 2678898. PMID 17884825.