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Plant activating sequences: positively charged peptides are functional as transcriptional activation domains.

ABSTRACT: Plant sequences that act as transcriptional activation domains in yeast as well as in plants have been isolated by genetic selection in yeast. The selection was based on the reconstitution of a functional GAL4 transcriptional activator. Since the peptides show no homology with reported activation domains, they represent a new class of activating sequences. The sequence P1, which is 10 amino acids long, is the shortest functional activation domain reported. A cDNA that encodes the P14 class (peptides P14-P18) activating sequence have been cloned. The protein exhibits strong homology (higher than 50% amino acid identity) with the BBC1-related sequences, a highly conserved family of basic proteins containing nuclear localization signals. The P14 and P15 peptides are the most effective plant activating sequences. The P14 and P15 peptides are highly hydrophilic, positively charged and mostly unstructured. These properties are at odds with the ones usually found in known activation domains.

SUBMITTER: Estruch JJ

PROVIDER: S-EPMC308399 | biostudies-other | 1994 Sep

REPOSITORIES: biostudies-other

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Plant activating sequences: positively charged peptides are functional as transcriptional activation domains.

Estruch J J JJ Crossland L L Goff S A SA

Nucleic acids research 19940901 19

Plant sequences that act as transcriptional activation domains in yeast as well as in plants have been isolated by genetic selection in yeast. The selection was based on the reconstitution of a functional GAL4 transcriptional activator. Since the peptides show no homology with reported activation domains, they represent a new class of activating sequences. The sequence P1, which is 10 amino acids long, is the shortest functional activation domain reported. A cDNA that encodes the P14 class (pept ...[more]

PMID: 7937121

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Project description:Lacking an effective mechanism to safely and consistently enhance macromolecular uptake across the intestinal epithelium, prospects for successful development of oral therapeutic peptide drugs remain unlikely. We previously addressed this challenge by identifying an endogenous mechanism that controls intestinal paracellular permeability that can be activated by a peptide, termed PIP 640, which can increase cellular levels of phosphorylated myosin light chain at position S19 (MLC-pS19). Apical application in vitro or luminal application in vivo was shown to increase macromolecular solute transport within minutes that recovered completely within a few hours after removal. We now examine the nature of PIP 640-mediated permeability changes. Confluent Caco-2 cell monolayers treated with PIP 640 enhanced apical-to-basolateral (AB) transport of 4-kDa, but not 10-kDa, dextran. Expression and/or cellular distribution changes of tight junction (TJ) proteins were restricted to increased claudin-2 over a time course that correlated with an apparent shift in its distribution from the nucleus to the membrane fraction of the cell. PIP 640-mediated epithelial changes were distinct from the combined actions of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-?) and interferon gamma (IFN-?). While TNF-?/IFN-? treatment also increased MLC-pS19 levels, these cytokines enhanced AB transport for 70-kDa dextran and decreased occludin expression at TJs. Claudin-2-dependent changes induced by PIP 640 resulted in an AB transport bias for positively-charged macromolecules demonstrated in vitro using charge variants of 4-kDa dextrans and by comparing transport of salmon calcitonin to exenatide. Comparable outcomes of increased TJ localization of claudin-2 and enhanced transport of these therapeutic peptides that biased toward cationic characteristics was demonstrated in vivo following after intra-luminal injection into rat jejunum. Together, these data have shown a potential mechanism for PIP 640 to enhance paracellular permeability of solutes in the size range of small therapeutic peptides that is biased toward positively-charged solutes.

Dataset Information

Plant activating sequences: positively charged peptides are functional as transcriptional activation domains.

Publications

Plant activating sequences: positively charged peptides are functional as transcriptional activation domains.

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