tRNA pseudouridine synthase B family (IPR004802)

Short name: tRNA_PsdUridine_synth_B_fam

Overlapping homologous superfamilies

Family relationships


This family, found in archaea and eukaryotes, includes the only archaeal proteins markedly similar to bacterial TruB, the tRNA pseudouridine 55 synthase. However, among two related yeast proteins, the archaeal set matches yeast YLR175w far better than YNL292w. The first, termed centromere/microtubule binding protein 5 (CBF5), is an apparent rRNA pseudouridine synthase, while the second is the exclusive tRNA pseudouridine 55 synthase for both cytosolic and mitochondrial compartments. It is unclear whether archaeal proteins found by this entry modify tRNA, rRNA, or both.

Yeast CBF5 plays a central role in ribosomal RNA processing. It is a probable catalytic subunit of H/ACA small nucleolar ribonucleoprotein (H/ACA snoRNP) complex, which catalyzes pseudouridylation of rRNA. This involves the isomerization of uridine such that the ribose is subsequently attached to C5, instead of the normal N1. Its pseudouridine ('psi') residues may serve to stabilise the conformation of rRNAs. It may function as a pseudouridine synthase. It is also a centromeric DNA-CBF3-binding factor which is involved in mitotic chromosome segregation [PMID: 8336724, PMID: 9472021, PMID: 9848653, PMID: 10523634].

Human CBF5 homologue, DKC1 (also called Dyskerin), has been involved in a variety of disparate cellular functions. DKC1 isoform 1 is required for correct processing or intranuclear trafficking of TERC, the RNA component of the telomerase reverse transcriptase (TERT) holoenzyme [PMID: 16601202]. In Hela cells, overexpression of DKC1 isoform 3 promotes cell to cell and cell to substratum adhesion, increases the cell proliferation rate and leads to cytokeratin hyper-expression [PMID: 21820037]. Mutations in the human DKC1 gene cause the X-linked form of DC, a bone marrow failure syndrome characterised by mucosal leukoplakia, nail dystrophy, abnormal skin pigmentation, premature aging, stem cell dysfunction and increased susceptibility to cancer. DKC1 loss of function also causes the Hoyeraal-Hreidarsson syndrome, recognised as a severe X-DC allelic variant [PMID: 12437656, PMID: 15304085, PMID: 18802941, PMID: 17417794, PMID: 10591218, PMID: 10364516].

GO terms

Biological Process

GO:0006396 RNA processing

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.