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XB-ART-18998
Nucleic Acids Res 1995 Nov 25;2322:4583-90.
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HMG box 4 is the principal determinant of species specificity in the RNA polymerase I transcription factor UBF.

Cairns C , McStay B .


Abstract
Transcription of ribosomal genes requires, in addition to RNA polymerase I, the trans-acting factors UBF and Rib1 in Xenopus or SL1 in humans. RNA polymerase I transcription is remarkably species specific. Between closely related species SL1 is the sole determinant of this specificity. Between more distantly related species, however, UBF is also a component of this species specificity. Xenopus UBF cannot function in human RNA polymerase I transcription and human UBF cannot function in Xenopus RNA polymerase I transcription. Xenopus and human UBFs are remarkably similar at the amino acid sequence level, both containing multiple HMG box DNA binding motifs. The only major difference between xUBF and hUBF is the lack of a HMG box 4 equivalent in xUBF. Utilizing a series of hybrid UBF molecules we have identified HMG box 4 as the principal determinant of species specificity. Addition of human HMG box 4 to xUBF converts it to a form that functions in human RNA polymerase I transcription. Deletion of HMG box 4 from hUBF converts it to a form that functions in Xenopus RNA polymerase I transcription. Furthermore, mutations within Xenopus UBF demonstrate that UBF requires a precise arrangement and number of HMG boxes to function in RNA polymerase I transcription.

PubMed ID: 8524646
PMC ID: PMC307429
Article link: Nucleic Acids Res
Grant support: [+]

Species referenced: Xenopus
Genes referenced: mef2d ubtf
Antibodies: Ubtf Ab1

References [+] :
Bachvarov, The RNA polymerase I transcription factor xUBF contains 5 tandemly repeated HMG homology boxes. 1991, Pubmed, Xenbase