Protein Family Models

Proteins involved in steps 4 and 6 of the histidine biosynthesis pathway are contained in this family. Histidine is formed by several complex and distinct biochemical reactions catalysed by eight enzymes. The enzymes in this Pfam entry are called His6 and His7 in eukaryotes and HisA and HisF in prokaryotes. The structure of HisA is known to be a TIM barrel fold. In some archaeal HisA proteins the TIM barrel is composed of two tandem repeats of a half barrel e.g. Swiss:P05325 [2]. This family belong to the common phosphate binding site TIM barrel family [3]. [1]. 9332345. Paralogous histidine biosynthetic genes: evolutionary analysis of the Saccharomyces cerevisiae HIS6 and HIS7 genes. Fani R, Tamburini E, Mori E, Lazcano A, Lio P, Barberio C, Casalone E, Cavalieri D, Perito B, Polsinelli M,. Gene 1997;197:9-17. [2]. 8028028. The evolution of the histidine biosynthetic genes in prokaryotes: a common ancestor for the hisA and hisF genes. Fani R, Lio P, Chiarelli I, Bazzicalupo M;. J Mol Evol 1994;38:489-495. [3]. 11054297. Homology among (betaalpha)(8) barrels: implications for the evolution of metabolic pathways. Copley RR, Bork P;. J Mol Biol 2000;303:627-641. (from Pfam)

Date:

2024-10-16

Members of this family catalyse the reduction of the 5,6-double bond of a uridine residue on tRNA. Dihydrouridine modification of tRNA is widely observed in prokaryotes and eukaryotes, and also in some archae. Most dihydrouridines are found in the D loop of t-RNAs. The role of dihydrouridine in tRNA is currently unknown, but may increase conformational flexibility of the tRNA. It is likely that different family members have different substrate specificities, which may overlap. Dus 1 (Swiss:Q9HGN6) from Saccharomyces cerevisiae acts on pre-tRNA-Phe, while Dus 2 (Swiss:P53720) acts on pre-tRNA-Tyr and pre-tRNA-Leu. Dus 1 is active as a single subunit, requiring NADPH or NADH, and is stimulated by the presence of FAD [1]. Some family members may be targeted to the mitochondria and even have a role in mitochondria [1]. [1]. 12003496. A conserved family of Saccharomyces cerevisiae synthases effects dihydrouridine modification of tRNA. Xing F, Martzen MR, Phizicky EM;. RNA 2002;8:370-381. (from Pfam)

Date:

2024-10-16

1-(5-phosphoribosyl)-5-[(5-phosphoribosylamino)methylideneamino] imidazole-4-carboxamide isomerase is an enzyme involved in the biosynthesis of histidine, specifically catalyzing the fourth step in the pathway, by converting a specific intermediate molecule through an isomerization reaction

Date:

2024-11-16

This protein family consists of HisA, phosphoribosylformimino-5-aminoimidazole carboxamide ribotide isomerase, the enzyme catalyzing the fourth step in histidine biosynthesis. It is closely related to the enzyme HisF for the sixth step. Examples of this enzyme in Actinobacteria have been found to be bifunctional, also possessing phosphoribosylanthranilate isomerase activity [1]; the trusted cutoff here has now been raised to 275.0 to exclude the bifunctional group, now represented by model TIGR01919. HisA from Lactococcus lactis was reported to be inactive (MEDLINE:93322317).

Gene:

hisA

Date:

2021-04-27