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

tRNA-dihydrouridine synthase catalyzes the synthesis of dihydrouridine, a modified base found in the D-loop of most tRNAs

Date:

2018-03-07

This model represents one branch of COG0042 (Predicted TIM-barrel enzymes, possibly dehydrogenases, nifR3 family). This branch includes NifR3 itself, from Rhodobacter capsulatus. It excludes a broadly distributed but more sparsely populated subfamily that contains sll0926 from Synechocystis PCC6803, HI0634 from Haemophilus influenzae, and BB0225 from Borrelia burgdorferi. It also excludes a shorter and more distant archaeal subfamily. The function of nifR3, a member of this family, is unknown, but it is found in an operon with nitrogen-sensing two component regulators in Rhodobacter capsulatus. Members of this family show a distant relationship to alpha/beta (TIM) barrel enzymes such as dihydroorotate dehydrogenase and glycolate oxidase.

Gene:

dusB

Date:

2024-06-27