Formation of composite nucleoprotein complexes near the transcription start of the Shrunken gene from maize

Springer, Boris; Bellmann, Regina; Werr, Wolfgang

doi:10.1007/bf00280373

Cited by 4 publications

(3 citation statements)

References 27 publications

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“…Also footprinting experiments performed at IBP polypeptide concentrations equal or higher than protecting the initiator element did not reveal any additional binding site in the Sh promoter (data not shown). A DNA-binding activity covering the Sh transcription start site has previously been observed also in DNase I footprinting experiments performed with maize nuclear protein extracts [34]. We conclude from these data that the initiator element contains a unique high affinity binding site in the Sh promoter.…”

Section: Dna-binding and Sequence Specificitysupporting

confidence: 60%

A novel DNA-binding domain in theShrunken initiator-binding protein (IBP1)

Lugert

Werr

1994

Plant Mol Biol

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South-western screening of lambda gt11 expression library with a fragment of the Shrunken promoter containing the initiator element resulted in cloning of a novel maize gene. The encoded initiator-binding protein (IBP1) interacts at the transcription start site of the Shrunken promoter. Analysis of the 680 amino acid (aa) long polypeptide revealed a novel bipartite DNA-binding domain at the carboxyl terminus. In its amino-terminal part, it is weakly related to Myb R-repeats but the following basic region is also essential for DNA binding. A region of similarity to the conserved 2.1 and 2.2 motifs in bacterial sigma-factors is located close to the IBP1 amino terminus. Two putative nuclear localization signals are compatible with the presence of antigenically related polypeptides in nuclear protein extracts. The IBP1 gene was mapped to the long arm of chromosome 9 (9L095); a second highly related gene IBP2 is located on the short arm of chromosome 1 (1S014). Both genes encode proteins sharing 93% similarity and are transcribed with similar activity in different plant organs. A small 82 nucleotide intron in the IBP2 transcript is found unspliced to a variable degree in different tissues. Translation of this incompletely processed transcript would result in a truncated amino-terminal polypeptide lacking the DNA-binding domain.

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Section: Dna-binding and Sequence Specificitysupporting

confidence: 60%

A novel DNA-binding domain in theShrunken initiator-binding protein (IBP1)

Lugert

Werr

1994

Plant Mol Biol

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“…The lymphocyte specific initiator element at the transcription start of the terminal deoxynucleo-tidyltransferase gene is also sufficient for transcriptional initiation and control (Smale and Baltimore, 1989), while additional upstream elements are required for high transcriptional activity of the initiator. As other small Sh promoter elements or individual binding sites for nuclear proteins (Springer et al, 1990) enhance transcriptional activity if inserted in front of the CaMV core promoter (C. Maas and W.Werr, unpublished), the type of regulation exhibited near the transcription start of the Sh promoter seems to be dominant over the binding of positively acting transcription factors. This may be due, in part, to the redundancy of regulatory elements, as indicated by promoter fusion experiments (see SP201447 NPT in Table I).…”

Section: Discussionmentioning

confidence: 99%

A feedback control element near the transcription start site of the maize Shrunken gene determines promoter activity.

1990

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The transcriptional activity of the Shrunken (Sh) promoter of Zea mays was monitored in transient expression assays using the neomycin phosphotransferase (NPT) II gene as a reporter in maize suspension protoplasts. Shortly after transfection, expression of this chimeric NPTII gene was negatively affected by high extracellular sucrose concentrations in the protoplast cultivation medium. However, 3‐5 days after transfection an up to 405‐fold increase in NPTII activity was observed. This could be blocked by dichlorobenzonitril (DCB) an inhibitor of cellulose biosynthesis. In the analysis of promoter deletions 20 bp upstream of the Sh transcription start site were sufficient to reproduce the expression profile and the activity of the full promoter. Surprisingly this start sequence does not include the natural TATA‐box.

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“…It should be pointed out that the only IBP1 binding site in the Sh-1 promoter is at the transcription start site. Many additional regulatory protein-DNA interactions occur in the upstream region which surely contribute to Sh-1 tissue speci®city (Springer et al 1990). …”

Section: Ibp Transcription Is Characteristic Of Elongating Cells In Tmentioning

confidence: 99%

The IBP genes of maize are expressed in non-meristematic, elongating cells of the seedling and in abortive floral organs

1997

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The transcription start site of the maize Shrunken-1 (Sh-1) gene is sufficient for transcriptional initiation in the absence of other promoter elements and is recognized in vitro by the Initiator Binding Protein (IBP). We describe here in situ hybridization experiments performed on various maize tissues to quantify IBP transcription at the cellular level. IBP transcripts are found in the endosperm and in differentiating, enlarging cells of the shoot and the root of the maize seedling. This expression pattern overlaps with that of the Sh-1 gene and is therefore compatible with the hypothesis that the Sh-1 transcription start site is a target for IBP. In the developing spikelets of male and female inflorescences IBP transcript levels are very high in those organs that are later aborted when flowers become unisexual. Overexpression of the maize IBP1 gene product in transgenic tobacco causes a reduction in internodal elongation and effects gibberellin hormonal balance. The cellular expression pattern described here establishes IBP transcripts as an interesting molecular marker for enlarging, and presumably differentiating, cells released from the root or shoot apex.

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Formation of composite nucleoprotein complexes near the transcription start of the Shrunken gene from maize

Cited by 4 publications

References 27 publications

A novel DNA-binding domain in theShrunken initiator-binding protein (IBP1)

A novel DNA-binding domain in theShrunken initiator-binding protein (IBP1)

A feedback control element near the transcription start site of the maize Shrunken gene determines promoter activity.

The IBP genes of maize are expressed in non-meristematic, elongating cells of the seedling and in abortive floral organs

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