Localization of competence-induced proteins in Streptococcus pneumoniae

Vijayakumar, M. N.; Morrison, Donald A.

doi:10.1128/jb.165.3.689-695.1986

Cited by 27 publications

(18 citation statements)

References 19 publications

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“…In this regard, it is noteworthy that our experiments were conducted using phosphodiester-linked ODNs that could be detected within transfected cells for only 6 to 8 hours. In this regard, p21/Waf1 and p16 have relatively short half-lives (Ͻ30 minutes) (Schwaller et al, 1997;Timchenko et al, 1996;Vijayakumar and Morrison, 1986), and correspondingly we were able to detect significant increases in the levels of these proteins after antisense AAH ODN transfection. These results are consistent with our hypothesis that AAH overexpression contributes to the malignant phenotype by modulating the expression of genes that regulate cell cycle progression or invasive growth.…”

Section: Sepe Et Almentioning

confidence: 60%

Role of the Aspartyl-Asparaginyl-β-Hydroxylase Gene in Neuroblastoma Cell Motility

Sepe

Lahousse

Gemelli

et al. 2002

Laboratory Investigation

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SUMMARY:Aspartyl (asparaginyl) ␤-hydroxylase (AAH) is overexpressed in various malignant neoplasms, and high levels of immunoreactivity mainly occur in infiltrating or metastasized tumors. In addition, AAH is abundantly expressed in normally invasive placental trophoblastic cells. These observations led to the hypothesis that AAH may have a role in motility and aggressive behavior of tumor cells. The present study demonstrates that AAH is overexpressed in primary human malignant neuroectodermal tumors, including medulloblastomas and neuroblastomas, and that AAH expression is at a low level or undetectable in the normal mature brain. In the Sy5y neuroblastoma cell line, endogenous expression of the~86-kd AAH protein was demonstrated by Western blot analysis, and immunoreactivity predominantly localized to the cell surface by immunocytochemical staining and FACS analysis. Sy5y cells that were stably transfected with the human AAH cDNA had increased levels of proliferating cell nuclear antigen and Bcl-2, and reduced levels of p21/Waf1 and p16. In addition, increased AAH expression enhanced Sy5y cell motility, whereas antisense oligodeoxynucleotide inhibition of AAH significantly reduced Sy5y cell motility and increased the levels of p21/Waf1 and p16. The findings suggest that AAH overexpression contributes to the malignant phenotype of neuroectodermal tumor cells by increasing motility and enhancing proliferation, survival, and cell cycle progression. Because AAH expression is at a low level or undetectable in normal brain, the AAH gene may be a target for treating primitive neuroectodermal tumors. (Lab Invest 2002, 82:881-891).

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Section: Sepe Et Almentioning

confidence: 60%

Role of the Aspartyl-Asparaginyl-β-Hydroxylase Gene in Neuroblastoma Cell Motility

Sepe

Lahousse

Gemelli

et al. 2002

Laboratory Investigation

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“…4). Nicking activity was observed in fractions 21,22,23,24,27, and 28 of the G-200 chromatography for the supernatant prepared from LiCl-treated competent culture. DNA-binding activity was eluted in the same fractions showing nickase activity, and both activities exhibited two peaks (Fig.…”

Section: Resultsmentioning

confidence: 99%

LiCl treatment releases a nickase implicated in genetic transformation of Streptococcus pneumoniae

et al. 1987

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When cells competent for genetic transformation of Streptococcus pneumonuae which could bind and enable entry of extracellular DNA molecules were treated with LiCl, they released a nickase that introduced nicks into a double-stranded DNA in the presence of EDTA. The nickase was specific for competent cells and coupled with DNA-binding activit. Furthermore, when noncompetent cells were treated with LiCl, they released the putative receptors for the competence activator.

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“…Therefore, it is more likely that transport of the T-complex occurs in a single step through a structure that spans both bacterial membranes. Transport of complex molecules in a single step through two membranes at discrete contact sites has been described for at least five systems: (i) uptake of DNA into competent B. subtilis and Streptococcus pneumoniae cells (14,50), (ii) import of proteins and a protein-DNA complex into mitochondria (36,39,49), (iii) export of filamentous phage DNA from E. coli (40), (iv) export of hemolysin from E. coli (6,19,21,22), and (v) transfer of DNA in bacterial conjugation (43). Based on information about these well-studied transport systems, it is likely that the T-DNA transport apparatus is dynamic, with the ability to open and close in response to the transportable substrate and maybe also in response to the presence of the host plant.…”

Section: Discussionmentioning

confidence: 99%

Subcellular localization of seven VirB proteins of Agrobacterium tumefaciens: implications for the formation of a T-DNA transport structure

1993

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Plant cell transformation by Agrobacteriwun Iwefaciens involves the transfer of a single-stranded DNAprotein complex (T-complex) from the bacterium to the plant cell. One of the least understood and important aspects of this process is how the T-complex exits the bacterium. The eleven virB gene products have been proposed to specify the DNA export channel on the basis of their predicted hydrophobicity. To determine the cellular localization of the VirB proteins, two different cell fractionation methods were employed to separate inner and outer membranes. Seven VirB-specific antibodies were used on Western blots (immunoblots) to detect the proteins in the inner and outer membranes and soluble (containing cytoplasm and periplasm) fractions. VirB5 was in both the inner membrane and cytoplasm. Six of the VwrB proteins were detected in the membrane fractions only. Three of these, VWrB8, VirB9, and VWrBlO, were present in both inner and outer membrane fractions regardless of the fractionation method used. Three additional VwrB proteins, VirBi, VWrB4, and VWrB1I, were found mainly in the inner membrane fraction by one method and were found in both inner and outer membrane fractions by a second method. These results confirm the membrane localization of seven VirB proteins and strengthen the hypothesis that VirB proteins are involved in the formation of a T-DNA export channel or gate. That most of the VwrB proteins analyzed are found in both inner and outer membrane fractions suggest that they form a complex pore structure that spans both membranes, and their relative amounts in the two membrane fractions reflect their differential sensitivity to the experimental conditions. Agrobacterium tumefaciens has the unique ability to transfer DNA to plant cells. In nature, the transfer and expression of a specific fragment of DNA (T-DNA) cause a neoplastic growth on the plant host. In the laboratory, this DNA transfer phenomenon has been exploited by using disarmed vectors to introduce new genes into plants. The T-DNA and the components necessary for packaging and transfer of the single-stranded T-DNA (T-strand) (45) are encoded by the tumor-inducing (Ti) plasmid in A. tumefaciens. The virulence (vir) region contains four operons (virA, virG, virD, and virB) that encode proteins required for virulence on all hosts (44). Three additional operons (virE, virC, and virH) encode proteins that are required only on some hosts (25,44).The transfer of DNA from the bacterium to the plant cell involves at least seven recognizable steps. Of the bacterial components necessary for DNA transfer, only the first step is thought to be mediated by chromosomally encoded functions (reviewed in reference 5). The remaining steps involve proteins that are encoded by the vir region on the Ti plasmid (reviewed in reference 59). The seven steps are as follows: (i) the bacterium binds to a specific component of the plant cell surface; (ii) a bacterial membrane protein (VirA) recognizes signals released by a wounded plant cell and transduces the signal v...

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Localization of competence-induced proteins in Streptococcus pneumoniae

Cited by 27 publications

References 19 publications

Role of the Aspartyl-Asparaginyl-β-Hydroxylase Gene in Neuroblastoma Cell Motility

Role of the Aspartyl-Asparaginyl-β-Hydroxylase Gene in Neuroblastoma Cell Motility

LiCl treatment releases a nickase implicated in genetic transformation of Streptococcus pneumoniae

Subcellular localization of seven VirB proteins of Agrobacterium tumefaciens: implications for the formation of a T-DNA transport structure

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