Conservative Val⁴⁷ residue of POU homeodomain: role in DNA recognition

Abstract

Conservative Val47 residue, located in the third recognition helix of the Oct-2 POU domain, was alternately substituted with other 19 amino acids. Affinity and specificity of interaction with oct-site ATGCAAANGA and homeo-specific site ATAANGA were determined for all mutants. The wild type protein (with Val 47 ) has maximal affinity and specificity in POU domain interaction with octamer sequence. However, V47I mutant showed stronger interaction with homeo-specific site. The highest specificity of interaction with homeo-site was recorded for V47S mutant. We conclude that only Val 47 provides sequence-specific high-affinity binding of POU proteins with octamer targets other than the homeo-specific site. It is shown also that damages caused by point mutations may be at least partially compensated by participation in the oct-site recognition of both POUh and POUs domains.© 1997 Federation of European Biochemical Societies.

Oct‐1 promoter region contains octamer sites and TAAT motifs recognized by Oct proteins

“…POU proteins share a highly conservative DNA binding domain (POU domain) which may be subdivided into two subdomains termed POU specific (POUs) and POU homeo (POUh) domain [1]. As shown by our and others' studies of Oct protein interactions with TAAT‐core sites in vitro, only POUh domain binds to these sites [16–19]. However, the entire POU domain is involved in the interaction with the canonical oct site ATGCAAAT.…”

An I47L substitution in the HOXD13 homeodomain causes a novel human limb malformation by producing a selective loss of function

“…An artificial I47A substitution in engrailed reduces DNA binding affinity 10-to 20-fold in vitro (Ades and Sauer, 1995), while an I47Q substitution in the Para-Hox protein IPF1 abolishes DNA binding in vitro and greatly reduces transcriptional activation in transfected cells (Lu et al, 1996). A V47L substitution in the POU homeodomain protein Oct2 also abolishes DNA binding in vitro (Stepchenko et al, 1997). No I47L substitution, however, has yet been analysed.…”

Tissue-specific isoforms of the ubiquitous transcription factor Oct-1

“…Cooperative interaction with Oct-1 has been shown for several transcription factors: Sp1 (Janson and Petterson 1990;Strom et al 1996), Ap-1 (Kaushansky et al 1994;Delhase et al 1996), NF-1 (O'Connor and Bernard 1995), steroid hormone receptor (Bruggemeier et al 1991), Pit-1 (Delhase et al 1996), and the homeobox protein Pbx (Subramaniam et al 1998). Second, pleiotropic functioning of Oct-1 and ®ne regulation of expression may proceed by interaction of Oct-1 with various DNA sites: the canonical oct site ATGCAAAT, non-canonical oct sites with single nucleotide substitutions, TAAT core sites, and TAATGARAT sites (Verrijzer et al 1992;Stepchenko 1992bStepchenko , 1994Stepchenko et al 1997aStepchenko et al , 1997b. The anity of Oct-1 for these sites is highly variable, and interaction with the co-activator OCA-B (Gstaiger et al 1995;Luo and Roeder 1995;Strubin et al 1995) and with VP-16 (O'Hare and Goding 1988) strictly depends on the site to which Oct-1 is bound.…”

“…We previously found A/T-rich clusters with TAAT core sites in this 5¢-terminal region. These sites are known to bind Oct-1 and Oct-2 proteins (Verrijzer et al 1992;Stepchenko 1992bStepchenko , 1994Stepchenko et al 1997aStepchenko et al , 1997bPankratova and Polanovsky 1998). Most of these TAAT core sites were also found in human DNA.…”