Mutant

About: Mutant is a research topic. Over the lifetime, 74520 publications have been published within this topic receiving 3477079 citations.

Cloning and characterization of the Pseudomonas aeruginosa lasR gene, a transcriptional activator of elastase expression.

Abstract: We report the discovery of the lasR gene, which positively regulates elastase expression in Pseudomonas aeruginosa PAO1. The lasR gene was cloned by its ability to restore a positive elastase phenotype in strain PA103, a strain which possesses the elastase structural gene (lasB) but fails to synthesize the enzyme. Nucleotide sequence analysis revealed an open reading frame of 716 nucleotides encoding a protein of approximately 27 kDa. A labeled LasR protein of 27 kDa was detected in Escherichia coli by using a T7 RNA polymerase expression system. A chromosomal deletion mutant of the lasR gene was constructed in PAO1 by gene replacement. This mutant (PAO-R1) is devoid of elastolytic activity and elastase antigen. The deduced amino acid sequence of LasR is 27% homologous to the positive activator LuxR of Vibrio fischeri and the suspected activator 28K-UvrC of E. coli. Northern (RNA) analysis of total cellular RNA from PAO1, PAO-R1, and PAO-R1 containing the lasR gene on a multicopy plasmid (pMG1.7) revealed that a functional lasR gene is required for transcription of the elastase structural gene (lasB). Images

Correction of a pathogenic gene mutation in human embryos

Abstract: Genome editing has potential for the targeted correction of germline mutations. Here we describe the correction of the heterozygous MYBPC3 mutation in human preimplantation embryos with precise CRISPR-Cas9-based targeting accuracy and high homology-directed repair efficiency by activating an endogenous, germline-specific DNA repair response. Induced double-strand breaks (DSBs) at the mutant paternal allele were predominantly repaired using the homologous wild-type maternal gene instead of a synthetic DNA template. By modulating the cell cycle stage at which the DSB was induced, we were able to avoid mosaicism in cleaving embryos and achieve a high yield of homozygous embryos carrying the wild-type MYBPC3 gene without evidence of off-target mutations. The efficiency, accuracy and safety of the approach presented suggest that it has potential to be used for the correction of heritable mutations in human embryos by complementing preimplantation genetic diagnosis. However, much remains to be considered before clinical applications, including the reproducibility of the technique with other heterozygous mutations.

Mutant p53 Gain-of-Function in Cancer

Abstract: In its wild-type form, p53 is a major tumor suppressor whose function is critical for protection against cancer. Many human tumors carry missense mutations in the TP53 gene, encoding p53. Typically, the affected tumor cells accumulate excessive amounts of the mutant p53 protein. Various lines of evidence indicate that, in addition to abrogating the tumor suppressor functions of wild-type p53, the common types of cancer-associated p53 mutations also endow the mutant protein with new activities that can contribute actively to various stages of tumor progression and to increased resistance to anticancer treatments. Collectively, these activities are referred to as mutant p53 gain-of-function. This article addresses the biological manifestations of mutant p53 gain-of-function, the underlying molecular mechanisms, and their possible clinical implications.

Sp1-mediated transcriptional activation is repressed by Sp3.

Abstract: Sp1, Sp3 (SPR-2) and Sp4 (SPR-1) are human sequence-specific DNA binding proteins with very similar structural features In this report, we have analyzed Sp3 in direct comparison with Sp1 We have raised antibodies against both Sp1 and Sp3, and show that Sp3 protein, like Sp1, is expressed in various cell lines Co-transfection experiments in different mammalian cell lines reveal that in contrast to Sp1 and Sp4, Sp3 is not able to activate several Sp1 responsive promoters In addition, Sp3 also fails to activate reporter constructs in Drosophila SL2 cells lacking endogenous Sp factors Instead, we find that Sp3 represses Sp1-mediated activation in a linear dose-dependent manner A mutant of Sp3 lacking the DNA binding domain does not affect activation by Sp1, suggesting that the inhibition is most likely due to the competition with Sp1 for their common binding sites To determine if any structurally similar domain of Sp3 is able to replace partially homologous domains of Sp1, we have generated chimeric proteins and tested their activation characteristics in gene transfer experiments It appears that neither the glutamine-rich domains A and B nor the D domain of Sp1 can be replaced by the homologous regions of Sp3 Our results suggest that Sp3 is an inhibitory member of the Sp family