NonO, a non-POU-domain-containing, octamer-binding protein, is the mammalian homolog of Drosophila nonAdiss

1993 ◽  
Vol 13 (9) ◽  
pp. 5593-5603
Author(s):  
Y S Yang ◽  
J H Hanke ◽  
L Carayannopoulos ◽  
C M Craft ◽  
J D Capra ◽  
...  

We have cloned the ubiquitous form of an octamer-binding, 60-kDa protein (NonO) that appears to be the mammalian equivalent of the Drosophila visual and courtship song behavior protein, no-on-transient A/dissonance (nonAdiss). A region unprecedently rich in aromatic amino acids containing two ribonuclear protein binding motifs is highly conserved between the two proteins. A ubiquitous form of NonO is present in all adult tissues, whereas lymphocytes and retina express unique forms of NonO mRNA. The ubiquitous form contains a potential helix-turn-helix motif followed by a highly charged region but differs from prototypic octamer-binding factors by lacking the POU DNA-binding domain. In addition to its conventional octamer duplex-binding, NonO binds single-stranded DNA and RNA at a site independent of the duplex site.

1993 ◽  
Vol 13 (9) ◽  
pp. 5593-5603 ◽  
Author(s):  
Y S Yang ◽  
J H Hanke ◽  
L Carayannopoulos ◽  
C M Craft ◽  
J D Capra ◽  
...  

We have cloned the ubiquitous form of an octamer-binding, 60-kDa protein (NonO) that appears to be the mammalian equivalent of the Drosophila visual and courtship song behavior protein, no-on-transient A/dissonance (nonAdiss). A region unprecedently rich in aromatic amino acids containing two ribonuclear protein binding motifs is highly conserved between the two proteins. A ubiquitous form of NonO is present in all adult tissues, whereas lymphocytes and retina express unique forms of NonO mRNA. The ubiquitous form contains a potential helix-turn-helix motif followed by a highly charged region but differs from prototypic octamer-binding factors by lacking the POU DNA-binding domain. In addition to its conventional octamer duplex-binding, NonO binds single-stranded DNA and RNA at a site independent of the duplex site.


1999 ◽  
Vol 181 (17) ◽  
pp. 5185-5192 ◽  
Author(s):  
Prasanna M. Bhende ◽  
Susan M. Egan

ABSTRACT RhaS, an AraC family protein, activates rhaBADtranscription by binding to rhaI, a site consisting of two 17-bp inverted repeat half-sites. In this work, amino acids in RhaS that make base-specific contacts with rhaI were identified. Sequence similarity with AraC suggested that the first contacting motif of RhaS was a helix-turn-helix. Assays of rhaB-lacZactivation by alanine mutants within this potential motif indicated that residues 201, 202, 205, and 206 might contact rhaI. The second motif was identified based on the hypothesis that a region of especially high amino acid similarity between RhaS and RhaR (another AraC family member) might contact the nearly identical DNA sequences in one major groove of their half-sites. We first made targeted, random mutations and then made alanine substitutions within this region of RhaS. Our analysis identified residues 247, 248, 250, 252, 253, and 254 as potentially important for DNA binding. A genetic loss-of-contact approach was used to identify whether any of the RhaS amino acids in the first or second contacting motif make base-specific DNA contacts. In motif 1, we found that Arg202 and Arg206 both make specific contacts with bp −65 and −67 in rhaI 1, and that Arg202 contacts −46 and Arg206 contacts −48 inrhaI 2. In motif 2, we found that Asp250 and Asn252 both contact the bp −79 in rhaI 1. Alignment with the recently crystallized MarA protein suggest that both RhaS motifs are likely helix-turn-helix DNA-binding motifs.


Planta ◽  
2021 ◽  
Vol 253 (2) ◽  
Author(s):  
Joung Sug Kim ◽  
SongHwa Chae ◽  
Kyong Mi Jun ◽  
Gang-Seob Lee ◽  
Jong-Seong Jeon ◽  
...  

Abstract Main conclusion The present study showed that a rice (Oryza sativa)-specific protein-binding microarray (RPBM) can be applied to analyze DNA-binding motifs with a TF where binding is evaluated in extended natural promoter regions. The analysis may facilitate identifying TFs and their downstream genes and constructing gene networks through cis-elements. Abstract Transcription factors (TFs) regulate gene expression at the transcriptional level by binding a specific DNA sequence. Thus, predicting the DNA-binding motifs of TFs is one of the most important areas in the functional analysis of TFs in the postgenomic era. Although many methods have been developed to address this challenge, many TFs still have unknown DNA-binding motifs. In this study, we designed RPBM with 40-bp probes and 20-bp of overlap, yielding 49 probes spanning the 1-kb upstream region before the translation start site of each gene in the entire genome. To confirm the efficiency of RPBM technology, we selected two previously studied TFs, OsWOX13 and OsSMF1, and an uncharacterized TF, OsWRKY34. We identified the ATTGATTG and CCACGTCA DNA-binding sequences of OsWOX13 and OsSMF1, respectively. In total, 635 and 932 putative feature genes were identified for OsWOX13 and OsSMF1, respectively. We discovered the CGTTGACTTT DNA-binding sequence and 195 putative feature genes of OsWRKY34. RPBM could be applicable in the analysis of DNA-binding motifs for TFs where binding is evaluated in the promoter and 5′ upstream CDS regions. The analysis may facilitate identifying TFs and their downstream genes and constructing gene networks through cis-elements.


1990 ◽  
Vol 10 (10) ◽  
pp. 5128-5137 ◽  
Author(s):  
M M Witte ◽  
R C Dickson

LAC9 is a DNA-binding protein that regulates transcription of the lactose-galactose regulon in Kluyveromyces lactis. The DNA-binding domain is composed of a zinc finger and nearby amino acids (M. M. Witte and R. C. Dickson, Mol. Cell. Biol. 8:3726-3733, 1988). The single zinc finger appears to be structurally related to the zinc finger of many other fungal transcription activator proteins that contain positively charged residues and six conserved cysteines with the general form Cys-Xaa2-Cys-Xaa6-Cys-Xaa6-9-Cys-Xaa2-Cys-Xaa 6-Cys, where Xaan indicates a stretch of the indicated number of any amino acids (R. M. Evans and S. M. Hollenberg, Cell 52:1-3, 1988). The function(s) of the zinc finger and other amino acids in DNA-binding remains unclear. To determine which portion of the LAC9 DNA-binding domain mediates sequence recognition, we replaced the C6 zinc finger, amino acids adjacent to the carboxyl side of the zinc finger, or both with the analogous region from the Saccharomyces cerevisiae PPR1 or LEU3 protein. A chimeric LAC9 protein, LAC9(PPR1 34-61), carrying only the PPR1 zinc finger, retained the DNA-binding specificity of LAC9. However, LAC9(PPR1 34-75), carrying the PPR1 zinc finger and 14 amino acids on the carboxyl side of the zinc finger, gained the DNA-binding specificity of PPR1, indicating that these 14 amino acids are necessary for specific DNA binding. Our data show that C6 fingers can substitute for each other and allow DNA binding, but binding affinity is reduced. Thus, in a qualitative sense C6 fingers perform a similar function(s). However, the high-affinity binding required by natural C6 finger proteins demands a unique C6 finger with a specific amino acid sequence. This requirement may reflect conformational constraints, including interactions between the C6 finger and the carboxyl-adjacent amino acids; alternatively or in addition, it may indicate that unique, nonconserved amino acid residues in zinc fingers make sequence-specifying or stabilizing contacts with DNA.


1994 ◽  
Vol 14 (9) ◽  
pp. 6056-6067
Author(s):  
M Tanaka ◽  
W Herr

The POU domain activator Oct-2 contains an N-terminal glutamine-rich transcriptional activation domain. An 18-amino-acid segment (Q18III) from this region reconstituted a fully functional activation domain when tandemly reiterated and fused to either the Oct-2 or GAL4 DNA-binding domain. A minimal transcriptional activation domain likely requires three tandem Q18III segments, because one or two tandem Q18III segments displayed little activity, whereas three to five tandem segments were active and displayed increasing activity with increasing copy number. As with natural Oct-2 activation domains, in our assay a reiterated activation domain required a second homologous or heterologous activation domain to stimulate transcription effectively when fused to the Oct-2 POU domain. These results suggest that there are different levels of synergy within and among activation domains. Analysis of reiterated activation domains containing mutated Q18III segments revealed that leucines and glutamines, but not serines or threonines, are critical for activity in vivo. Curiously, several reiterated activation domains that were inactive in vivo were active in vitro, suggesting that there are significant functional differences in our in vivo and in vitro assays. Reiteration of a second 18-amino-acid segment from the Oct-2 glutamine-rich activation domain (Q18II) was also active, but its activity was DNA-binding domain specific, because it was active when fused to the GAL4 than to the Oct-2 DNA-binding domain. The ability of separate short peptide segments derived from a single transcriptional activation domain to activate transcription after tandem reiteration emphasizes the flexible and modular nature of a transcriptional activation domain.


1999 ◽  
Vol 19 (4) ◽  
pp. 2880-2886 ◽  
Author(s):  
Asish K. Ghosh ◽  
Robert Steele ◽  
Ratna B. Ray

ABSTRACT We initially identified c-myc promoter binding protein 1 (MBP-1), which negatively regulates c-myc promoter activity, from a human cervical carcinoma cell expression library. Subsequent studies on the biological role of MBP-1 demonstrated induction of cell death in fibroblasts and loss of anchorage-independent growth, reduced invasive ability, and tumorigenicity of human breast carcinoma cells. To investigate the potential role of MBP-1 as a transcriptional regulator, a chimeric protein containing MBP-1 fused to the DNA binding domain of the yeast transactivator factor GAL4 was constructed. This fusion protein exhibited repressor activity on the herpes simplex virus thymidine kinase promoter via upstream GAL4 DNA binding sites. Structure-function analysis of mutant MBP-1 in the context of the GAL4 DNA binding domain revealed that MBP-1 transcriptional repressor domains are located in the N terminus (amino acids 1 to 47) and C terminus (amino acids 232 to 338), whereas the activation domain lies in the middle (amino acids 140 to 244). The N-terminal domain exhibited stronger transcriptional repressor activity than the C-terminal region. When the N-terminal repressor domain was transferred to a potent activator, transcription was strongly inhibited. Both of the repressor domains contained hydrophobic regions and had an LXVXL motif in common. Site-directed mutagenesis in the repressor domains indicated that the leucine residues in the LXVXL motif are required for transcriptional repression. Mutation of the leucine residues in the common motif of MBP-1 also abrogated the repressor activity on the c-mycpromoter. In addition, the leucine mutant forms of MBP-1 failed to suppress cell growth in fibroblasts like wild-type MBP-1. Taken together, our results indicate that MBP-1 is a complex cellular factor containing multiple transcriptional regulatory domains that play an important role in cell growth regulation.


1993 ◽  
Vol 13 (12) ◽  
pp. 7496-7506
Author(s):  
X Mao ◽  
M K Darby

Transcription of the Xenopus 5S RNA gene by RNA polymerase III requires the gene-specific factor TFIIIA. To identify domains within TFIIIA that are essential for transcriptional activation, we have expressed C-terminal deletion, substitution, and insertion mutants of TFIIIA in bacteria as fusions with maltose-binding protein (MBP). The MBP-TFIIIA fusion protein specifically binds to the 5S RNA gene internal control region and complements transcription in a TFIIIA-depleted oocyte nuclear extract. Random, cassette-mediated mutagenesis of the carboxyl region of TFIIIA, which is not required for promoter binding, has defined a 14-amino-acid region that is critical for transcriptional activation. In contrast to activators of RNA polymerase II, the activity of the TFIIIA activation domain is strikingly sensitive to its position relative to the DNA-binding domain. When the eight amino acids that separate the transcription-activating domain from the last zinc finger are deleted, transcriptional activity is lost. Surprisingly, diverse amino acids can replace these eight amino acids with restoration of full transcriptional activity, suggesting that the length and not the sequence of this region is important. Insertion of amino acids between the zinc finger region and the transcription-activating domain causes a reduction in transcription proportional to the number of amino acids introduced. We propose that to function, the transcription-activating domain of TFIIIA must be correctly positioned at a minimum distance from the DNA-binding domain.


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