hisK is missing in a number of organisms. There are clusters in some
of these organisms containing an inositol phosphatase.
I believe that some of these are, probably, Histidinol-phosphatase (EC 3.1.3.15).
I mentioned this to Joern Kalinowski who works with Corynebacterium at Bielefeld. He wrote
back saying that the gene I pointed to in Corynebacterium was not hisK, but
"although the report on the disruption of the impA gene within the his
gene cluster in Mycobacterium smegmatis did not sound encouraging, some
of our lab work revealed rather exciting news.
We found a histidine-auxotrophic phenotype in Corynebacterium glutamicum
by deleting an impA paralogous gene (NCgl0765). This gene is most
probably the missing hisK homolog."
This led to a very few assignments for hisK. I actually believe that both the gene mentioned by Joern and the one that clusters in Corynebacterium both implement the missing phosphatase.
In "Genome Properties: a system for the investigation of prokaryotic genetic content for microbiology, genome annotation, and comparative genomics", Haft, Selengut, Brinkac, Zafar, and White, Bioinformatics, Vol 21, no 3, p 293-306
the authors suggest that [GeneID:954516, NP_441180.1, gi|16330452, kegg|syn:sll1959, sll1959, suhB, tr|P73806, uni|P73806] is the missing hisK in Synechocystis. This is based on clustering they noted. I remain somewhat skeptical of this call, but in any case wet lab work will be needed to get at the truth
Note that hisK remains missing in over 50 of the complete genomes. In many cases it will surely turn out to be one of the genes identified as an inositol monophosphatase.
Nomenclature Clarification for Role Abbreviations: In the full version of the subsystem story posted on this supplementary material web-site, the E. coli nomenclature is used. However, in the actual subsystem Roy Jensen's nomenclature is used. The table below shows the correspondences between the abbreviations for the roles.
| Jensen | E. coli | Role |
|---|---|---|
| hisA | hisG | ATP phosphoribosyltransferase |
| hisAb | hisZ | tRNA homolog functioning as a regulatory unit |
| hisB | hisI (sometimes hisE) | Phosphoribosyl-ATP pyrophosphatase |
| hisC | hisI | Phosphoribosyl-AMP cyclohydrolase |
| hisD | hisA | Phosphoribosylformimino-5-aminoimidazole carboxamide |
| hisEa | hisF | Imidazole glycerol phosphate synthase cyclase subunit |
| hisEb | hisH | Imidazole glycerol phosphate synthase amidotransferase |
| hisF | hisB | Imidazoleglycerol-phosphate dehydratase |
| hisG | hisC | Histidinol-phosphate aminotransferase |
| hisH | hisB (sometimes hisK or hisJ) | Histidinol-phosphatase |
| hisI | hisD | Histidinol dehydrogenase |