6330 Nucleic Acids Research, Vol. 19, No. 22 .::) 1991 Oxford University Press

A unique bipartite - motif defines a subfamily of potential zinc-finger

Bramham A.Reddy and Laurence D.Etkin* Department of Molecular Genetics, University of Texas M.D. Anderson Cancer Center,1515 Holcombe Blvd, Houston, TX 77030, USA

Submitted September 18, 1991

Recently, a new potential zinc finger motif was described of the likely that the B box also is involved in nucleic acid binding, class Cl-C2 X C3-H -C4-C5 X C6-C7 (C3HC4) where the and/or -protein interactions. two spacers (X) vary between 11-27 and 6-17 amino acids. This group includes BMI-1, RAG-I and at least 11 other proteins ACKNOWLEDGEMENT found in a variety of organisms from viruses to human (1, 2). We have described a nuclear protein in Xenopus laevis, XNF7, This work was supported by N.S.F. grants DCB-8608690 and that is sequestered in the cytoplasm until the mid-blastula stage DCB9007410 to L.D.E. of development when it enters the nuclei (3, 4, 5). We believe that the XNF7 protein may function as a transcription factor. REFERENCES The XNF7 protein possesses a motif that is identical to the previously described C3HC4 motif (1) that we call the A box 1. Freemont,P.S., Hanson,I.M. and Trowsdale,J. (1991) Cell 64, 483-484. 2. Haupt,Y., Alexander,W.S., Barri,G., Klinken,S.P. and Adams,J.M. (1991) (Table 1). In addition, a second novel C-H domain located 39 Cell 65, 753-763. amino acids downstream from the A box in XNF7 defines a new 3. Reddy,B., Kloc,M. and Etkin,L.D. (1991) Dev. Biol. in press. class of C-H structures (C-H 15 C-C 5 H-H) that we refer 4. Miller,M., Reddy,B., Kloc,M., Li,X., Dreyer,C. and Etkin,L.D. (1991) to as the B box. The B box motif is also found in the RET proto- Development, in press. RPT-1, a down regulator of the interleukin 2 5. Miller,M., Kloc,M., Reddy,B., Eastman,E., Dreyer,C. and Etkin,L.D. oncogene (6), (1989) Genes Dev. 3, 572-583. receptor gene and the HIV LTR (7), SS-A/Ro, an RNA binding 6. Takahashi,M., Inaguma,Y., Hiai,H. and Hirose,F. (1988) Mol. Cell. Biol. autoantigen (8), and in the PML gene, that may be a myeloid 8, 1853-1856. specific transcription factor found fused to the retinoic acid 7. Patarca,R., Schwartz,J., Singh,R. et al. (1988) Proc. Natl. Acad. Sci. USA receptor gene in Promyelocytic Leukemia (9, 10). In all of these 85, 2733-2737. toward 8. Chan,E.K.L., Hamel,J.C., Buyon,J.P. and Tan,E.M. (1991) J. Clin. Invest. proteins the B box is located either 37 or 39 amino acids 87, 68-76. the carboxy terminus from the A box (Table 1). Searches of the 9. Kakizuka,A. et al. (1991) Cell 66, 663-674. PIR (version 27.0) data base which contains 26,798 protein 10. de The,H. et al. (1991) Cell 66, 675-684. sequences and the Swiss protein data base (release 17.0) that contains 20,772 entries revealed that the B box is only in the RET, SS-A/Ro, RPT-1, PML, and XNF7 proteins and is always found associated with the A box. Thus, these proteins comprise XNF7 7.CPL_qVELFKDPVMVACGNMFCRSf,IDKAWEGNSSFA.QPECR a subfamily of the C3HC4 family recently described by Consensus -g-IS- Freemont et al. (1). 1 2 3 4 5 6 7 Unlike the A box there is a high degree of conservation in the spacing between the C and H pairs in the B box among four of XNF7 Xenopus gSDEPRLXLYCXDDGTLStVIgRDSLXIASI RZT Human £EPIZPLXLYC)ZED IPIVVpDRSRZPRGI the proteins. The distance between CH and CC is 15 amino acids SS-A/Ro Human CAVIVGERLHLFcZIWGXALWVE&QSR[DII while the CC HH spacer contains 5 amino acids. Also, there are RPT-1 Mouse _AQIGhELRL7CRXD3OWIRWL.CRSQIIRGI[ several identical amino acids between the potential zinc finger PHL Human CTRXEXSADFWCFECEQLL¢FE FEA--IQWFLKI structures in the B box. The PML protein has diverged slightly Consensus in that H1 is replaced by a C and the spacing varies at carboxy 1 1 2 3 2 3 terminal portion of the B box (Table 1). While there is some Table 1. Two potential zinc-finger domains in protein XNF7. The A Box (aa homology outside of the consensus sequences between the RET, 144-185) of XNF7 is aligned with the previously derived C3HC4 consensus RPT-1 and SS-A/Ro, there is no significant homology between sequence (1). The B Box of XNF7 (aa 224-255) is aligned with the similar these proteins and XNF7 other than the described C-H domains. sequences present in RET, SS-A/Ro, RPT-1, and PML showing the consensus sequence of this new motif. The B Box is exactly 39 amino acids downstream Recent evidence has shown that a synthetic containing of A Box in XNF7 and RET, while it is 37 amino acids in SS-A/Ro, RPT-1 the A box motif binds to zinc and DNA in vitro (P.Freemont, and PML. The references for the other proteins that have only the A Box can R.Lovering, and J.Trowsdale, personal communication). It is be found in Haupt et al. (2).

* To whom correspondence should be addressed